Merge branch 'mb/feature' into develop

35 files changed, 1157 insertions, 304 deletions

diff --git a/test/apps/test_index.py b/test/apps/test_index.py
index 9cdc656..7f5be8e 100644
--- a/test/apps/test_index.py
+++ b/test/apps/test_index.py
@@ -4,13 +4,15 @@ Part of the bsie test suite.
 A copy of the license is provided with the project.
 Author: Matthias Baumgartner, 2022
 """
-# imports
+# standard imports
 import contextlib
 import io
 import os
-import rdflib
 import unittest
 
+# external imports
+import rdflib
+
 # bsie imports
 from bsie.utils import ns
 
@@ -21,6 +23,12 @@ from bsie.apps.index import main
 ## code ##
 
 class TestIndex(unittest.TestCase):
+    def test_main_invalid(self):
+        outbuf = io.StringIO()
+        with contextlib.redirect_stdout(outbuf):
+            bsfs = main([os.path.join(os.path.dirname(__file__), 'inexistent-file.t')])
+        self.assertEqual(outbuf.getvalue().strip(), '')
+
     def test_main(self):
         bsfs = main([
             '-r',
@@ -75,6 +83,14 @@ class TestIndex(unittest.TestCase):
             (rdflib.URIRef(prefix + 'd803187cbf3676ae9d38126270a6152c60431589aa3bb3824baf8954e9c097f1'), rdflib.URIRef(ns.bse.author), rdflib.Literal('Me, myself, and I', datatype=rdflib.XSD.string)),
             (rdflib.URIRef(prefix + 'd803187cbf3676ae9d38126270a6152c60431589aa3bb3824baf8954e9c097f1'), rdflib.URIRef(ns.bse.filename), rdflib.Literal('td_second', datatype=rdflib.XSD.string)),
             (rdflib.URIRef(prefix + 'd803187cbf3676ae9d38126270a6152c60431589aa3bb3824baf8954e9c097f1'), rdflib.URIRef(ns.bse.filesize), rdflib.Literal('703', datatype=rdflib.XSD.integer)),
+            (rdflib.URIRef(prefix + 'accb115d266ad60c53cd01a7f7130f245886ce8eaf69bc85319febc11d9fe089'), rdflib.RDF.type, rdflib.URIRef(ns.bsfs.File)),
+            (rdflib.URIRef(prefix + 'accb115d266ad60c53cd01a7f7130f245886ce8eaf69bc85319febc11d9fe089'), rdflib.URIRef(ns.bse.author), rdflib.Literal('Me, myself, and I', datatype=rdflib.XSD.string)),
+            (rdflib.URIRef(prefix + 'accb115d266ad60c53cd01a7f7130f245886ce8eaf69bc85319febc11d9fe089'), rdflib.URIRef(ns.bse.filename), rdflib.Literal('testimage.jpg', datatype=rdflib.XSD.string)),
+            (rdflib.URIRef(prefix + 'accb115d266ad60c53cd01a7f7130f245886ce8eaf69bc85319febc11d9fe089'), rdflib.URIRef(ns.bse.filesize), rdflib.Literal('349264', datatype=rdflib.XSD.integer)),
+            (rdflib.URIRef(prefix + 'accb115d266ad60c53cd01a7f7130f245886ce8eaf69bc85319febc11d9fe089'), rdflib.URIRef('http://bsfs.ai/schema/Entity/colors_spatial#0658f2234a054e1dd59a14462c89f7733e019160419c796356aa831498bd0a04'),
+                rdflib.Literal(
+                    '(91, 127, 121, 94, 138, 167, 163, 134, 190, 138, 170, 156, 121, 142, 159)',
+                    datatype=rdflib.URIRef('http://ie.bsfs.ai/schema/Feature/ColorsSpatial#0658f2234a054e1dd59a14462c89f7733e019160419c796356aa831498bd0a04'))),
             }))
 
         # NOTE: we don't check ns.bsm.t_created since it depends on the execution time. Triples would look like this:
@@ -89,6 +105,7 @@ class TestIndex(unittest.TestCase):
         #   (rdflib.URIRef(prefix + 'b8fd7fba818254166a6043195004138ebda6923e012442f819a2c49671136c70'), rdflib.URIRef(ns.bsm.t_created), rdflib.Literal('1670..........', datatype=rdflib.XSD.integer)),
         #   (rdflib.URIRef(prefix + 'd43758ace82154a1cc10ca0dfef63cb20dd831f9c87edd6dc06539eefe67371d'), rdflib.URIRef(ns.bsm.t_created), rdflib.Literal('1670..........', datatype=rdflib.XSD.integer)),
         #   (rdflib.URIRef(prefix + 'd803187cbf3676ae9d38126270a6152c60431589aa3bb3824baf8954e9c097f1'), rdflib.URIRef(ns.bsm.t_created), rdflib.Literal('1670..........', datatype=rdflib.XSD.integer)),
+        #   (rdflib.URIRef(prefix + 'accb115d266ad60c53cd01a7f7130f245886ce8eaf69bc85319febc11d9fe089'), rdflib.URIRef(ns.bsm.t_created), rdflib.Literal('1670..........', datatype=rdflib.XSD.integer)),
         # instead, we simply check if there's such a predicate for each file
         self.assertSetEqual({sub for sub, _ in bsfs._backend._graph.subject_objects(rdflib.URIRef(ns.bsm.t_created))}, {
             rdflib.URIRef(prefix + '2f4109b40107cc50e0884755a1a961ed126887e49b8dbaf0e146b2e226aa6647'),
@@ -102,6 +119,7 @@ class TestIndex(unittest.TestCase):
             rdflib.URIRef(prefix + 'b8fd7fba818254166a6043195004138ebda6923e012442f819a2c49671136c70'),
             rdflib.URIRef(prefix + 'd43758ace82154a1cc10ca0dfef63cb20dd831f9c87edd6dc06539eefe67371d'),
             rdflib.URIRef(prefix + 'd803187cbf3676ae9d38126270a6152c60431589aa3bb3824baf8954e9c097f1'),
+            rdflib.URIRef(prefix + 'accb115d266ad60c53cd01a7f7130f245886ce8eaf69bc85319febc11d9fe089'),
             })
 
     def test_print(self):
@@ -148,6 +166,10 @@ class TestIndex(unittest.TestCase):
             f'Node(http://bsfs.ai/schema/File, http://example.com/me/file#d803187cbf3676ae9d38126270a6152c60431589aa3bb3824baf8954e9c097f1) Predicate({ns.bse.author}) Me, myself, and I',
             f'Node(http://bsfs.ai/schema/File, http://example.com/me/file#d803187cbf3676ae9d38126270a6152c60431589aa3bb3824baf8954e9c097f1) Predicate({ns.bse.filename}) td_second',
             f'Node(http://bsfs.ai/schema/File, http://example.com/me/file#d803187cbf3676ae9d38126270a6152c60431589aa3bb3824baf8954e9c097f1) Predicate({ns.bse.filesize}) 703',
+            f'Node(http://bsfs.ai/schema/File, http://example.com/me/file#accb115d266ad60c53cd01a7f7130f245886ce8eaf69bc85319febc11d9fe089) Predicate({ns.bse.filesize}) 349264',
+            f'Node(http://bsfs.ai/schema/File, http://example.com/me/file#accb115d266ad60c53cd01a7f7130f245886ce8eaf69bc85319febc11d9fe089) Predicate({ns.bse.author}) Me, myself, and I',
+            f'Node(http://bsfs.ai/schema/File, http://example.com/me/file#accb115d266ad60c53cd01a7f7130f245886ce8eaf69bc85319febc11d9fe089) Predicate({ns.bse.filename}) testimage.jpg',
+            f'Node(http://bsfs.ai/schema/File, http://example.com/me/file#accb115d266ad60c53cd01a7f7130f245886ce8eaf69bc85319febc11d9fe089) Predicate(http://bsfs.ai/schema/Entity/colors_spatial#0658f2234a054e1dd59a14462c89f7733e019160419c796356aa831498bd0a04) (91, 127, 121, 94, 138, 167, 163, 134, 190, 138, 170, 156, 121, 142, 159)',
             })
 
 
diff --git a/test/apps/test_info.py b/test/apps/test_info.py
index 6f4d98f..60e9ba1 100644
--- a/test/apps/test_info.py
+++ b/test/apps/test_info.py
@@ -4,12 +4,15 @@ Part of the bsie test suite.
 A copy of the license is provided with the project.
 Author: Matthias Baumgartner, 2022
 """
-# imports
+# standard imports
 import argparse
 import contextlib
 import io
 import unittest
 
+# bsie imports
+from bsie.utils import bsfs
+
 # objects to test
 from bsie.apps.info import main
 
@@ -28,6 +31,22 @@ class TestIndex(unittest.TestCase):
             'http://bsfs.ai/schema/Predicate',
             'http://bsfs.ai/schema/Entity#filename',
             'http://bsfs.ai/schema/Entity#filesize',
+            'http://bsfs.ai/schema/Entity/colors_spatial#0658f2234a054e1dd59a14462c89f7733e019160419c796356aa831498bd0a04'
+            })
+
+    def test_schema(self):
+        outbuf = io.StringIO()
+        with contextlib.redirect_stdout(outbuf):
+            # show schema infos
+            main(['schema'])
+        # verify output
+        schema = bsfs.schema.from_string(outbuf.getvalue())
+        self.assertSetEqual({pred.uri for pred in schema.predicates()}, {
+            'http://bsfs.ai/schema/Entity#author',
+            'http://bsfs.ai/schema/Predicate',
+            'http://bsfs.ai/schema/Entity#filename',
+            'http://bsfs.ai/schema/Entity#filesize',
+            'http://bsfs.ai/schema/Entity/colors_spatial#0658f2234a054e1dd59a14462c89f7733e019160419c796356aa831498bd0a04'
             })
 
     def test_invalid(self):
diff --git a/test/apps/testdir/testimage.jpg b/test/apps/testdir/testimage.jpg
new file mode 100644
index 0000000..c80bb48
--- /dev/null
+++ b/test/apps/testdir/testimage.jpg
diff --git a/test/extractor/generic/test_constant.py b/test/extractor/generic/test_constant.py
index 9dbaced..bde3805 100644
--- a/test/extractor/generic/test_constant.py
+++ b/test/extractor/generic/test_constant.py
@@ -4,7 +4,7 @@ Part of the bsie test suite.
 A copy of the license is provided with the project.
 Author: Matthias Baumgartner, 2022
 """
-# imports
+# standard imports
 import unittest
 
 # bsie imports
@@ -36,19 +36,19 @@ class TestConstant(unittest.TestCase):
         node = _node.Node(ns.bsfs.Entity, '') # Blank node
         p_author = ext.schema.predicate(ns.bse.author)
         p_comment = ext.schema.predicate(ns.bse.comment)
-        entity = ext.schema.node(ns.bsfs.Node).get_child(ns.bsfs.Entity)
-        string = ext.schema.literal(ns.bsfs.Literal).get_child(ns.xsd.string)
+        entity = ext.schema.node(ns.bsfs.Node).child(ns.bsfs.Entity)
+        string = ext.schema.literal(ns.bsfs.Literal).child(ns.xsd.string)
         # baseline
         self.assertSetEqual(set(ext.extract(node, None, (p_author, p_comment))),
             {(node, p_author, 'Me, myself, and I'),
              (node, p_comment, 'the quick brown fox jumps over the lazy dog.')})
         # predicates is respected
-        p_foobar = ext.schema.predicate(ns.bsfs.Predicate).get_child(ns.bse.foobar, domain=entity, range=entity)
+        p_foobar = ext.schema.predicate(ns.bsfs.Predicate).child(ns.bse.foobar, domain=entity, range=entity)
         self.assertSetEqual(set(ext.extract(node, None, (p_author, p_foobar))),
             {(node, p_author, 'Me, myself, and I')})
         self.assertSetEqual(set(ext.extract(node, None, (p_comment, p_foobar))),
             {(node, p_comment, 'the quick brown fox jumps over the lazy dog.')})
-        p_barfoo = ext.schema.predicate(ns.bse.author).get_child(ns.bse.comment, domain=entity, range=string)
+        p_barfoo = ext.schema.predicate(ns.bse.author).child(ns.bse.comment, domain=entity, range=string)
         self.assertSetEqual(set(ext.extract(node, None, (p_foobar, p_barfoo))), set())
 
     def test_construct(self):
diff --git a/test/extractor/generic/test_path.py b/test/extractor/generic/test_path.py
index 820f402..ae68686 100644
--- a/test/extractor/generic/test_path.py
+++ b/test/extractor/generic/test_path.py
@@ -4,11 +4,11 @@ Part of the bsie test suite.
 A copy of the license is provided with the project.
 Author: Matthias Baumgartner, 2022
 """
-# imports
+# standard imports
 import unittest
 
 # bsie imports
-from bsie.base import extractor
+from bsie.extractor import base
 from bsie.utils import bsfs, node as _node, ns
 
 # objects to test
@@ -29,7 +29,7 @@ class TestPath(unittest.TestCase):
 
     def test_schema(self):
         self.assertEqual(Path().schema,
-            bsfs.schema.Schema.from_string(extractor.SCHEMA_PREAMBLE + '''
+            bsfs.schema.from_string(base.SCHEMA_PREAMBLE + '''
                 bse:filename rdfs:subClassOf bsfs:Predicate ;
                     rdfs:domain bsfs:File ;
                     rdfs:range xsd:string ;
@@ -41,19 +41,19 @@ class TestPath(unittest.TestCase):
         node = _node.Node(ns.bsfs.File, '') # Blank node
         content = '/tmp/foo/bar'
         p_filename = ext.schema.predicate(ns.bse.filename)
-        entity = ext.schema.node(ns.bsfs.Node).get_child(ns.bsfs.Entity)
-        string = ext.schema.literal(ns.bsfs.Literal).get_child(ns.xsd.string)
+        entity = ext.schema.node(ns.bsfs.Node).child(ns.bsfs.Entity)
+        string = ext.schema.literal(ns.bsfs.Literal).child(ns.xsd.string)
 
         # baseline
         self.assertSetEqual(set(ext.extract(node, content, (p_filename, ))),
             {(node, p_filename, 'bar')})
         # predicates parameter is respected
-        p_foo = ext.schema.predicate(ns.bsfs.Predicate).get_child(ns.bse.foo, domain=entity, range=string) # unsupported predicate
+        p_foo = ext.schema.predicate(ns.bsfs.Predicate).child(ns.bse.foo, domain=entity, range=string) # unsupported predicate
         self.assertSetEqual(set(ext.extract(node, content, (p_filename, p_foo))),
             {(node, p_filename, 'bar')})
         self.assertSetEqual(set(ext.extract(node, content, (p_foo, ))), set())
         # predicates are validated
-        p_bar = p_foo.get_child(ns.bse.filename) # same URI but different hierarchy
+        p_bar = p_foo.child(ns.bse.filename) # same URI but different hierarchy
         self.assertSetEqual(set(ext.extract(node, content, (p_filename, p_bar))),
             {(node, p_filename, 'bar')})
         self.assertSetEqual(set(ext.extract(node, content, (p_bar, ))), set())
diff --git a/test/extractor/generic/test_stat.py b/test/extractor/generic/test_stat.py
index 3441438..e5562d1 100644
--- a/test/extractor/generic/test_stat.py
+++ b/test/extractor/generic/test_stat.py
@@ -4,12 +4,12 @@ Part of the bsie test suite.
 A copy of the license is provided with the project.
 Author: Matthias Baumgartner, 2022
 """
-# imports
+# standard imports
 import os
 import unittest
 
 # bsie imports
-from bsie.base import extractor
+from bsie.extractor import base
 from bsie.utils import bsfs, node as _node, ns
 
 # objects to test
@@ -30,7 +30,7 @@ class TestStat(unittest.TestCase):
 
     def test_schema(self):
         self.assertEqual(Stat().schema,
-            bsfs.schema.Schema.from_string(extractor.SCHEMA_PREAMBLE + '''
+            bsfs.schema.from_string(base.SCHEMA_PREAMBLE + '''
                 bse:filesize rdfs:subClassOf bsfs:Predicate ;
                     rdfs:domain bsfs:File ;
                     rdfs:range xsd:integer ;
@@ -42,19 +42,19 @@ class TestStat(unittest.TestCase):
         node = _node.Node(ns.bsfs.File, '') # Blank node
         content = os.stat(__file__)
         p_filesize = ext.schema.predicate(ns.bse.filesize)
-        entity = ext.schema.node(ns.bsfs.Node).get_child(ns.bsfs.Entity)
-        string = ext.schema.literal(ns.bsfs.Literal).get_child(ns.xsd.string)
+        entity = ext.schema.node(ns.bsfs.Node).child(ns.bsfs.Entity)
+        string = ext.schema.literal(ns.bsfs.Literal).child(ns.xsd.string)
 
         # baseline
         self.assertSetEqual(set(ext.extract(node, content, (p_filesize, ))),
             {(node, p_filesize, content.st_size)})
         # predicates parameter is respected
-        p_foo = ext.schema.predicate(ns.bsfs.Predicate).get_child(ns.bse.foo, domain=entity, range=string) # unsupported predicate
+        p_foo = ext.schema.predicate(ns.bsfs.Predicate).child(ns.bse.foo, domain=entity, range=string) # unsupported predicate
         self.assertSetEqual(set(ext.extract(node, content, (p_filesize, p_foo))),
             {(node, p_filesize, content.st_size)})
         self.assertSetEqual(set(ext.extract(node, content, (p_foo, ))), set())
         # predicates are validated
-        p_bar = p_foo.get_child(ns.bse.filesizse) # same URI but different hierarchy
+        p_bar = p_foo.child(ns.bse.filesizse) # same URI but different hierarchy
         self.assertSetEqual(set(ext.extract(node, content, (p_filesize, p_bar))),
             {(node, p_filesize, content.st_size)})
         self.assertSetEqual(set(ext.extract(node, content, (p_bar, ))), set())
diff --git a/test/base/__init__.py b/test/extractor/image/__init__.py
index e69de29..e69de29 100644
--- a/test/base/__init__.py
+++ b/test/extractor/image/__init__.py
diff --git a/test/extractor/image/test_colors_spatial.py b/test/extractor/image/test_colors_spatial.py
new file mode 100644
index 0000000..ba551f3
--- /dev/null
+++ b/test/extractor/image/test_colors_spatial.py
@@ -0,0 +1,100 @@
+"""
+
+Part of the bsie test suite.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+import os
+import unittest
+
+# external imports
+import PIL.Image
+
+# bsie imports
+from bsie.extractor import base
+from bsie.utils import bsfs, ns, node as _node
+
+# objects to test
+from bsie.extractor.image.colors_spatial import ColorsSpatial
+
+
+## code ##
+
+class TestColorsSpatial(unittest.TestCase):
+    def setUp(self):
+        # content id with default constructors (width=32, height=32, exp=4)
+        self.instance_prefix = 'http://ie.bsfs.ai/schema/Feature/ColorsSpatial'
+        self.predicate_prefix = 'http://bsfs.ai/schema/Entity/colors_spatial'
+        self.uuid = 'adee8d6c43687021e1c5bffe56bcfe727f1638d792744137181304ef889dac2a'
+
+    def test_essentials(self):
+        # clones are equal
+        self.assertEqual(ColorsSpatial(32, 32, 4), ColorsSpatial(32, 32, 4))
+        self.assertEqual(hash(ColorsSpatial(32, 32, 4)), hash(ColorsSpatial(32, 32, 4)))
+        # equal respects type
+        self.assertNotEqual(ColorsSpatial(32, 32, 4), 'hello world')
+        self.assertNotEqual(hash(ColorsSpatial(32, 32, 4)), hash('hello world'))
+        # equals respects width
+        self.assertNotEqual(ColorsSpatial(32, 32, 4), ColorsSpatial(16, 32, 4))
+        self.assertNotEqual(hash(ColorsSpatial(32, 32, 4)), hash(ColorsSpatial(16, 32, 4)))
+        # equals respects height
+        self.assertNotEqual(ColorsSpatial(32, 32, 4), ColorsSpatial(32, 16, 4))
+        self.assertNotEqual(hash(ColorsSpatial(32, 32, 4)), hash(ColorsSpatial(32, 16, 4)))
+        # equals respects exp
+        self.assertNotEqual(ColorsSpatial(32, 32, 4), ColorsSpatial(32, 32, 8))
+        self.assertNotEqual(hash(ColorsSpatial(32, 32, 4)), hash(ColorsSpatial(32, 32, 8)))
+        # string representation
+        self.assertEqual(str(ColorsSpatial()), 'ColorsSpatial')
+        self.assertEqual(repr(ColorsSpatial(64, 16, 2)), 'ColorsSpatial(64, 16, 2)')
+
+    def test_dimension(self):
+        self.assertEqual(ColorsSpatial.dimension(32, 32, 4), 3 * (32*32 + 8*8 + 2*2))
+        self.assertEqual(ColorsSpatial.dimension(16, 16, 8), 3 * (16*16 + 2*2))
+        self.assertEqual(ColorsSpatial.dimension(64, 64, 16), 3 * (64*64 + 4*4))
+
+    def test_schema(self):
+        schema = bsfs.schema.from_string(base.SCHEMA_PREAMBLE + f'''
+            <{self.instance_prefix}> rdfs:subClassOf bsfs:Feature ;
+                # annotations
+                rdfs:label "Spatially dominant colors"^^xsd:string ;
+                schema:description "Domiant colors of subregions in an image."^^xsd:string ;
+                bsfs:dtype xsd:integer .
+
+            <{self.instance_prefix}#{self.uuid}> rdfs:subClassOf <{self.instance_prefix}> ;
+                bsfs:dimension "3276"^^xsd:integer ;
+                # annotations
+                <{self.instance_prefix}/args#width> "32"^^xsd:integer ;
+                <{self.instance_prefix}/args#height> "32"^^xsd:integer ;
+                <{self.instance_prefix}/args#exp> "4"^^xsd:float .
+
+            <{self.predicate_prefix}#{self.uuid}> rdfs:subClassOf bsfs:Predicate ;
+                rdfs:domain bsfs:File ;
+                rdfs:range <{self.instance_prefix}#{self.uuid}> ;
+                bsfs:unique "true"^^xsd:boolean .
+            ''')
+        self.assertEqual(schema, ColorsSpatial().schema)
+
+    def test_extract(self):
+        ext = ColorsSpatial(2,2,2)
+        img = PIL.Image.open(os.path.join(os.path.dirname(__file__), 'testimage.jpg'))
+        node = _node.Node(ns.bsfs.Entity, bsfs.URI('http://example.com/entity#1234'))
+        principals = set(ext.principals)
+        self.assertEqual(len(principals), 1)
+        # valid invocation yields feature
+        ret = list(ext.extract(node, img, principals))
+        self.assertEqual(ret[0], (
+            node,
+            list(principals)[0],
+            (91, 127, 121, 94, 138, 167, 163, 134, 190, 138, 170, 156, 121, 142, 159)))
+        # principals is respected
+        self.assertListEqual(list(ext.extract(node, img, {})), [])
+
+
+
+## main ##
+
+if __name__ == '__main__':
+    unittest.main()
+
+## EOF ##
diff --git a/test/extractor/image/testimage.jpg b/test/extractor/image/testimage.jpg
new file mode 100644
index 0000000..c80bb48
--- /dev/null
+++ b/test/extractor/image/testimage.jpg
diff --git a/test/base/test_extractor.py b/test/extractor/test_base.py
index 30974ef..acfaf58 100644
--- a/test/base/test_extractor.py
+++ b/test/extractor/test_base.py
@@ -4,21 +4,21 @@ Part of the bsie test suite.
 A copy of the license is provided with the project.
 Author: Matthias Baumgartner, 2022
 """
-# imports
+# standard imports
 import unittest
 
 # bsie imports
 from bsie.utils import bsfs, ns
 
 # objects to test
-from bsie.base import extractor
+from bsie.extractor import base
 
 
 ## code ##
 
-class StubExtractor(extractor.Extractor):
+class StubExtractor(base.Extractor):
     def __init__(self):
-        super().__init__(bsfs.schema.Schema.from_string(extractor.SCHEMA_PREAMBLE + '''
+        super().__init__(bsfs.schema.from_string(base.SCHEMA_PREAMBLE + '''
             bse:author rdfs:subClassOf bsfs:Predicate ;
                 rdfs:domain bsfs:Entity ;
                 rdfs:range xsd:string ;
@@ -52,11 +52,11 @@ class TestExtractor(unittest.TestCase):
         self.assertNotEqual(hash(ext), hash(sub))
 
     def test_principals(self):
-        schema = bsfs.schema.Schema.Empty()
-        entity = schema.node(ns.bsfs.Node).get_child(ns.bsfs.Entity)
-        string = schema.literal(ns.bsfs.Literal).get_child(bsfs.URI('http://www.w3.org/2001/XMLSchema#string'))
-        p_author = schema.predicate(ns.bsfs.Predicate).get_child(ns.bse.author, domain=entity, range=string)
-        p_comment = schema.predicate(ns.bsfs.Predicate).get_child(ns.bse.comment, domain=entity, range=string)
+        schema = bsfs.schema.Schema()
+        entity = schema.node(ns.bsfs.Node).child(ns.bsfs.Entity)
+        string = schema.literal(ns.bsfs.Literal).child(bsfs.URI('http://www.w3.org/2001/XMLSchema#string'))
+        p_author = schema.predicate(ns.bsfs.Predicate).child(ns.bse.author, domain=entity, range=string)
+        p_comment = schema.predicate(ns.bsfs.Predicate).child(ns.bse.comment, domain=entity, range=string)
         ext = StubExtractor()
         self.assertSetEqual(set(ext.principals),
             {p_author, p_comment} | set(schema.predicates()) - {schema.predicate(ns.bsfs.Predicate)})
diff --git a/test/extractor/test_builder.py b/test/extractor/test_builder.py
new file mode 100644
index 0000000..039ea53
--- /dev/null
+++ b/test/extractor/test_builder.py
@@ -0,0 +1,103 @@
+"""
+
+Part of the bsie test suite.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+import unittest
+
+# bsie imports
+from bsie.utils import errors
+
+# objects to test
+from bsie.extractor import ExtractorBuilder
+
+
+## code ##
+
+class TestExtractorBuilder(unittest.TestCase):
+    def test_iter(self):
+        # no specifications
+        self.assertListEqual(list(ExtractorBuilder([])), [])
+        # some specifications
+        builder = ExtractorBuilder([
+            {'bsie.extractor.generic.path.Path': {}},
+            {'bsie.extractor.generic.stat.Stat': {}},
+            {'bsie.extractor.generic.path.Path': {}},
+            ])
+        self.assertListEqual(list(builder), [0, 1, 2])
+
+    def test_build(self):
+        # simple and repeated extractors
+        builder = ExtractorBuilder([
+            {'bsie.extractor.generic.path.Path': {}},
+            {'bsie.extractor.generic.stat.Stat': {}},
+            {'bsie.extractor.generic.path.Path': {}},
+            ])
+        ext = [builder.build(0), builder.build(1), builder.build(2)]
+        import bsie.extractor.generic.path
+        import bsie.extractor.generic.stat
+        self.assertListEqual(ext, [
+            bsie.extractor.generic.path.Path(),
+            bsie.extractor.generic.stat.Stat(),
+            bsie.extractor.generic.path.Path(),
+            ])
+        # out-of-bounds raises KeyError
+        self.assertRaises(IndexError, builder.build, 3)
+
+        # building with args
+        builder = ExtractorBuilder([
+            {'bsie.extractor.generic.constant.Constant': {
+                'schema': '''
+                    bse:author rdfs:subClassOf bsfs:Predicate ;
+                        rdfs:domain bsfs:Entity ;
+                        rdfs:range xsd:string ;
+                        bsfs:unique "true"^^xsd:boolean .
+                    bse:rating rdfs:subClassOf bsfs:Predicate ;
+                        rdfs:domain bsfs:Entity ;
+                        rdfs:range xsd:integer ;
+                        bsfs:unique "true"^^xsd:boolean .
+                    ''',
+                'tuples': [
+                    ('http://bsfs.ai/schema/Entity#author', 'Me, myself, and I'),
+                    ('http://bsfs.ai/schema/Entity#rating', 123),
+                    ],
+            }}])
+        obj = builder.build(0)
+        import bsie.extractor.generic.constant
+        self.assertEqual(obj, bsie.extractor.generic.constant.Constant('''
+                    bse:author rdfs:subClassOf bsfs:Predicate ;
+                        rdfs:domain bsfs:Entity ;
+                        rdfs:range xsd:string ;
+                        bsfs:unique "true"^^xsd:boolean .
+                    bse:rating rdfs:subClassOf bsfs:Predicate ;
+                        rdfs:domain bsfs:Entity ;
+                        rdfs:range xsd:integer ;
+                        bsfs:unique "true"^^xsd:boolean .
+                    ''', [
+            ('http://bsfs.ai/schema/Entity#author', 'Me, myself, and I'),
+            ('http://bsfs.ai/schema/Entity#rating', 123),
+            ]))
+
+        # building with invalid args
+        self.assertRaises(errors.BuilderError, ExtractorBuilder(
+            [{'bsie.extractor.generic.path.Path': {'foo': 123}}]).build, 0)
+        # non-dict build specification
+        self.assertRaises(TypeError, ExtractorBuilder(
+            [('bsie.extractor.generic.path.Path', {})]).build, 0)
+        # multiple keys per build specification
+        self.assertRaises(TypeError, ExtractorBuilder(
+            [{'bsie.extractor.generic.path.Path': {},
+              'bsie.extractor.generic.stat.Stat': {}}]).build, 0)
+        # non-dict value for kwargs
+        self.assertRaises(TypeError, ExtractorBuilder(
+            [{'bsie.extractor.generic.path.Path': 123}]).build, 0)
+
+
+## main ##
+
+if __name__ == '__main__':
+    unittest.main()
+
+## EOF ##
diff --git a/test/lib/test_bsie.py b/test/lib/test_bsie.py
index 771a0c2..38e6f59 100644
--- a/test/lib/test_bsie.py
+++ b/test/lib/test_bsie.py
@@ -4,13 +4,15 @@ Part of the bsie test suite.
 A copy of the license is provided with the project.
 Author: Matthias Baumgartner, 2022
 """
-# imports
+# standard imports
 import os
 import unittest
 
 # bsie imports
-from bsie.base import extractor
-from bsie.tools import builder
+from bsie.extractor import ExtractorBuilder
+from bsie.extractor.base import SCHEMA_PREAMBLE
+from bsie.lib import PipelineBuilder
+from bsie.reader import ReaderBuilder
 from bsie.utils import bsfs, node, ns
 
 # objects to test
@@ -22,9 +24,9 @@ from bsie.lib.bsie import BSIE
 class TestBSIE(unittest.TestCase):
     def setUp(self):
         # reader builder
-        rbuild = builder.ReaderBuilder({})
+        rbuild = ReaderBuilder({})
         # extractor builder
-        ebuild = builder.ExtractorBuilder([
+        ebuild = ExtractorBuilder([
             {'bsie.extractor.generic.path.Path': {}},
             {'bsie.extractor.generic.stat.Stat': {}},
             {'bsie.extractor.generic.constant.Constant': dict(
@@ -39,7 +41,7 @@ class TestBSIE(unittest.TestCase):
             ])
         # build pipeline
         self.prefix = bsfs.Namespace('http://example.com/local/')
-        pbuild = builder.PipelineBuilder(self.prefix, rbuild, ebuild)
+        pbuild = PipelineBuilder(self.prefix, rbuild, ebuild)
         self.pipeline = pbuild.build()
 
     def test_construction(self):
@@ -50,7 +52,7 @@ class TestBSIE(unittest.TestCase):
             ns.bse.filesize,
             ns.bse.author,
             })
-        self.assertEqual(lib.schema, bsfs.schema.Schema.from_string(extractor.SCHEMA_PREAMBLE + '''
+        self.assertEqual(lib.schema, bsfs.schema.from_string(SCHEMA_PREAMBLE + '''
             bse:filename rdfs:subClassOf bsfs:Predicate ;
                 rdfs:domain bsfs:File ;
                 rdfs:range xsd:string ;
@@ -77,7 +79,7 @@ class TestBSIE(unittest.TestCase):
             ns.bse.filesize,
             ns.bse.author,
             })
-        self.assertEqual(lib.schema, bsfs.schema.Schema.from_string(extractor.SCHEMA_PREAMBLE + '''
+        self.assertEqual(lib.schema, bsfs.schema.from_string(SCHEMA_PREAMBLE + '''
             bse:filesize rdfs:subClassOf bsfs:Predicate ;
                 rdfs:domain bsfs:File ;
                 rdfs:range xsd:integer;
@@ -95,7 +97,7 @@ class TestBSIE(unittest.TestCase):
             ns.bse.filesize,
             ns.bse.author,
             })
-        self.assertEqual(lib.schema, bsfs.schema.Schema.from_string(extractor.SCHEMA_PREAMBLE + '''
+        self.assertEqual(lib.schema, bsfs.schema.from_string(SCHEMA_PREAMBLE + '''
             bse:filename rdfs:subClassOf bsfs:Predicate ;
                 rdfs:domain bsfs:File ;
                 rdfs:range xsd:string ;
@@ -122,7 +124,7 @@ class TestBSIE(unittest.TestCase):
         self.assertSetEqual(set(lib.principals), {
             ns.bse.author,
             })
-        self.assertEqual(lib.schema, bsfs.schema.Schema.from_string(extractor.SCHEMA_PREAMBLE + '''
+        self.assertEqual(lib.schema, bsfs.schema.from_string(SCHEMA_PREAMBLE + '''
             bse:author rdfs:subClassOf bsfs:Predicate ;
                 rdfs:domain bsfs:Entity ;
                 rdfs:range xsd:string ;
@@ -137,7 +139,7 @@ class TestBSIE(unittest.TestCase):
         self.assertSetEqual(set(lib.principals), {
             ns.bse.filesize,
             })
-        self.assertEqual(lib.schema, bsfs.schema.Schema.from_string(extractor.SCHEMA_PREAMBLE + '''
+        self.assertEqual(lib.schema, bsfs.schema.from_string(SCHEMA_PREAMBLE + '''
             bse:filesize rdfs:subClassOf bsfs:Predicate ;
                 rdfs:domain bsfs:File ;
                 rdfs:range xsd:integer;
diff --git a/test/lib/test_builder.py b/test/lib/test_builder.py
new file mode 100644
index 0000000..273d620
--- /dev/null
+++ b/test/lib/test_builder.py
@@ -0,0 +1,107 @@
+"""
+
+Part of the bsie test suite.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+import logging
+import unittest
+
+# bsie imports
+from bsie.extractor import ExtractorBuilder
+from bsie.reader import ReaderBuilder
+from bsie.utils import bsfs
+
+# objects to test
+from bsie.lib import PipelineBuilder
+
+
+## code ##
+
+class TestPipelineBuilder(unittest.TestCase):
+    def test_build(self):
+        prefix = bsfs.URI('http://example.com/local/file#')
+        c_schema = '''
+            bse:author rdfs:subClassOf bsfs:Predicate ;
+                rdfs:domain bsfs:Entity ;
+                rdfs:range xsd:string ;
+                bsfs:unique "true"^^xsd:boolean .
+            '''
+        c_tuples = [('http://bsfs.ai/schema/Entity#author', 'Me, myself, and I')]
+        # prepare builders
+        rbuild = ReaderBuilder({})
+        ebuild = ExtractorBuilder([
+            {'bsie.extractor.generic.path.Path': {}},
+            {'bsie.extractor.generic.stat.Stat': {}},
+            {'bsie.extractor.generic.constant.Constant': dict(
+                schema=c_schema,
+                tuples=c_tuples,
+                )},
+            ])
+        # build pipeline
+        builder = PipelineBuilder(prefix, rbuild, ebuild)
+        pipeline = builder.build()
+        # delayed import
+        import bsie.reader.path
+        import bsie.reader.stat
+        import bsie.extractor.generic.path
+        import bsie.extractor.generic.stat
+        import bsie.extractor.generic.constant
+        # check pipeline
+        self.assertDictEqual(pipeline._ext2rdr, {
+            bsie.extractor.generic.path.Path(): bsie.reader.path.Path(),
+            bsie.extractor.generic.stat.Stat(): bsie.reader.stat.Stat(),
+            bsie.extractor.generic.constant.Constant(c_schema, c_tuples): None,
+            })
+
+        # fail to load extractor
+        ebuild_err = ExtractorBuilder([
+            {'bsie.extractor.generic.foo.Foo': {}},
+            {'bsie.extractor.generic.path.Path': {}},
+            ])
+        with self.assertLogs(logging.getLogger('bsie.lib.builder'), logging.ERROR):
+            pipeline = PipelineBuilder(prefix, rbuild, ebuild_err).build()
+            self.assertDictEqual(pipeline._ext2rdr, {
+                bsie.extractor.generic.path.Path(): bsie.reader.path.Path()})
+
+        # fail to build extractor
+        ebuild_err = ExtractorBuilder([
+            {'bsie.extractor.generic.path.Path': {'foo': 123}},
+            {'bsie.extractor.generic.path.Path': {}},
+            ])
+        with self.assertLogs(logging.getLogger('bsie.lib.builder'), logging.ERROR):
+            pipeline = PipelineBuilder(prefix, rbuild, ebuild_err).build()
+            self.assertDictEqual(pipeline._ext2rdr, {
+                bsie.extractor.generic.path.Path(): bsie.reader.path.Path()})
+
+        # fail to load reader
+        with self.assertLogs(logging.getLogger('bsie.lib.builder'), logging.ERROR):
+            # switch reader of an extractor
+            old_reader = bsie.extractor.generic.path.Path.CONTENT_READER
+            bsie.extractor.generic.path.Path.CONTENT_READER = 'bsie.reader.foo.Foo'
+            # build pipeline with invalid reader reference
+            pipeline = PipelineBuilder(prefix, rbuild, ebuild).build()
+            self.assertDictEqual(pipeline._ext2rdr, {
+                bsie.extractor.generic.stat.Stat(): bsie.reader.stat.Stat(),
+                bsie.extractor.generic.constant.Constant(c_schema, c_tuples): None,
+                })
+            # switch back
+            bsie.extractor.generic.path.Path.CONTENT_READER = old_reader
+
+        # fail to build reader
+        rbuild_err = ReaderBuilder({'bsie.reader.stat.Stat': dict(foo=123)})
+        with self.assertLogs(logging.getLogger('bsie.lib.builder'), logging.ERROR):
+            pipeline = PipelineBuilder(prefix, rbuild_err, ebuild).build()
+            self.assertDictEqual(pipeline._ext2rdr, {
+                bsie.extractor.generic.path.Path(): bsie.reader.path.Path(),
+                bsie.extractor.generic.constant.Constant(c_schema, c_tuples): None,
+                })
+
+
+## main ##
+
+if __name__ == '__main__':
+    unittest.main()
+
+## EOF ##
diff --git a/test/tools/test_pipeline.py b/test/lib/test_pipeline.py
index a116a30..8fecc74 100644
--- a/test/tools/test_pipeline.py
+++ b/test/lib/test_pipeline.py
@@ -4,14 +4,13 @@ Part of the bsie test suite.
 A copy of the license is provided with the project.
 Author: Matthias Baumgartner, 2022
 """
-# imports
+# standard imports
 import logging
 import os
 import unittest
 
 # bsie imports
-from bsie.base import errors
-from bsie.utils import bsfs, node, ns
+from bsie.utils import bsfs, errors, node, ns
 import bsie.extractor.generic.constant
 import bsie.extractor.generic.path
 import bsie.extractor.generic.stat
@@ -19,7 +18,7 @@ import bsie.reader.path
 import bsie.reader.stat
 
 # objects to test
-from bsie.tools.pipeline import Pipeline
+from bsie.lib.pipeline import Pipeline
 
 
 ## code ##
@@ -75,7 +74,7 @@ class TestPipeline(unittest.TestCase):
 
         # equivalence respects schema
         p2 = Pipeline(self.prefix, self.ext2rdr)
-        p2._schema = pipeline.schema.Empty()
+        p2._schema = bsfs.schema.Schema()
         self.assertNotEqual(pipeline, p2)
         self.assertNotEqual(hash(pipeline), hash(p2))
 
@@ -101,7 +100,7 @@ class TestPipeline(unittest.TestCase):
         p_author = pipeline.schema.predicate(ns.bse.author)
         p_rating = pipeline.schema.predicate(ns.bse.rating)
         entity = pipeline.schema.node(ns.bsfs.File)
-        p_invalid = pipeline.schema.predicate(ns.bsfs.Predicate).get_child(ns.bse.foo, range=entity)
+        p_invalid = pipeline.schema.predicate(ns.bsfs.Predicate).child(ns.bse.foo, range=entity)
 
         # extract given predicates
         self.assertSetEqual(set(pipeline(testfile, {p_filename, p_filesize})), {
@@ -140,7 +139,7 @@ class TestPipeline(unittest.TestCase):
                 raise errors.ReaderError('reader error')
 
         pipeline = Pipeline(self.prefix, {bsie.extractor.generic.path.Path(): FaultyReader()})
-        with self.assertLogs(logging.getLogger('bsie.tools.pipeline'), logging.ERROR):
+        with self.assertLogs(logging.getLogger('bsie.lib.pipeline'), logging.ERROR):
             testfile = os.path.join(os.path.dirname(__file__), 'testfile.t')
             p_filename = pipeline.schema.predicate(ns.bse.filename)
             self.assertSetEqual(set(pipeline(testfile, {p_filename})), set())
@@ -151,7 +150,7 @@ class TestPipeline(unittest.TestCase):
                 raise errors.ExtractorError('extractor error')
 
         pipeline = Pipeline(self.prefix, {FaultyExtractor(): bsie.reader.path.Path()})
-        with self.assertLogs(logging.getLogger('bsie.tools.pipeline'), logging.ERROR):
+        with self.assertLogs(logging.getLogger('bsie.lib.pipeline'), logging.ERROR):
             testfile = os.path.join(os.path.dirname(__file__), 'testfile.t')
             p_filename = pipeline.schema.predicate(ns.bse.filename)
             self.assertSetEqual(set(pipeline(testfile, {p_filename})), set())
diff --git a/test/tools/__init__.py b/test/reader/image/__init__.py
index e69de29..e69de29 100644
--- a/test/tools/__init__.py
+++ b/test/reader/image/__init__.py
diff --git a/test/reader/image/load_nef.py b/test/reader/image/load_nef.py
new file mode 100644
index 0000000..5ba0adc
--- /dev/null
+++ b/test/reader/image/load_nef.py
@@ -0,0 +1,28 @@
+"""
+
+Part of the bsie test suite.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+import os
+
+# external imports
+import requests
+
+# constants
+IMAGE_URL = 'http://igsor.net/eik7AhvohghaeN5.nef'
+
+## code ##
+
+def get():
+    """Download a raw test image."""
+    target = os.path.join(os.path.dirname(__file__), 'testimage.nef')
+    if not os.path.exists(target):
+        with open(target, 'wb') as ofile:
+            ans = requests.get(IMAGE_URL)
+            ofile.write(ans.content)
+
+
+
+## EOF ##
diff --git a/test/reader/image/test_image.py b/test/reader/image/test_image.py
new file mode 100644
index 0000000..26f6a93
--- /dev/null
+++ b/test/reader/image/test_image.py
@@ -0,0 +1,54 @@
+"""
+
+Part of the bsie test suite.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+import importlib
+import os
+import unittest
+
+# bsie imports
+from bsie.utils import errors
+
+# objects to test
+from bsie.reader.image import Image
+
+
+## code ##
+
+class TestImage(unittest.TestCase):
+    def setUp(self):
+        if __package__ is None or __package__ == '': # direct call or local discovery
+            importlib.import_module('load_nef', __package__).get()
+        else: # parent discovery
+            importlib.import_module('.load_nef', __package__).get()
+
+    def test_construct(self):
+        image = Image({})
+        self.assertIsInstance(image, Image)
+        self.assertEqual(len(image._children), 2)
+
+    def test_call(self):
+        image = Image({})
+        # call returns raw image
+        img = image(os.path.join(os.path.dirname(__file__), 'testimage.nef'))
+        self.assertEqual(img.size, (6016, 4016)) # FIXME: change when image was replaced
+        img.close()
+        # call returns jpeg image
+        img = image(os.path.join(os.path.dirname(__file__), 'testimage.jpg'))
+        self.assertEqual(img.size, (1, 1))
+        img.close()
+        # call raises error if file cannot be read
+        self.assertRaises(errors.ReaderError, image,
+            os.path.join(os.path.dirname(__file__), 'invalid.nef'))
+        self.assertRaises(errors.ReaderError, image,
+            os.path.join(os.path.dirname(__file__), 'invalid.jpg'))
+
+## main ##
+
+if __name__ == '__main__':
+    unittest.main()
+
+## EOF ##
diff --git a/test/reader/image/test_pillow.py b/test/reader/image/test_pillow.py
new file mode 100644
index 0000000..8abf5c1
--- /dev/null
+++ b/test/reader/image/test_pillow.py
@@ -0,0 +1,44 @@
+"""
+
+Part of the bsie test suite.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+import os
+import unittest
+
+# external imports
+import PIL.Image
+
+# bsie imports
+from bsie.utils import errors
+
+# objects to test
+from bsie.reader.image._pillow import PillowImage
+
+
+## code ##
+
+class TestPillowImage(unittest.TestCase):
+    def test_call(self):
+        rdr = PillowImage()
+        # returns PIL image
+        img = rdr(os.path.join(os.path.dirname(__file__), 'testimage.jpg'))
+        self.assertEqual(img.size, (1, 1))
+        self.assertEqual(img.getdata().getpixel((0, 0)), (0, 0, 0))
+        img.close()
+        # raises exception when image cannot be read
+        self.assertRaises(errors.ReaderError, rdr,
+            os.path.join(os.path.dirname(__file__), 'invalid.jpg'))
+        # NOTE: PIL can actually read raw image files (returns the thumbnail)
+        #self.assertRaises(errors.ReaderError, rdr,
+        #    os.path.join(os.path.dirname(__file__), 'testimage.nef'))
+
+
+## main ##
+
+if __name__ == '__main__':
+    unittest.main()
+
+## EOF ##
diff --git a/test/reader/image/test_raw_image.py b/test/reader/image/test_raw_image.py
new file mode 100644
index 0000000..ba21b5a
--- /dev/null
+++ b/test/reader/image/test_raw_image.py
@@ -0,0 +1,53 @@
+"""
+
+Part of the bsie test suite.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+import importlib
+import os
+import unittest
+
+# external imports
+import PIL.Image
+
+# bsie imports
+from bsie.utils import errors
+
+# objects to test
+from bsie.reader.image._raw import RawImage
+
+
+## code ##
+
+class TestRawImage(unittest.TestCase):
+    def setUp(self):
+        if __package__ is None or __package__ == '': # direct call or local discovery
+            importlib.import_module('load_nef', __package__).get()
+        else: # parent discovery
+            importlib.import_module('.load_nef', __package__).get()
+
+    def test_call(self):
+        rdr = RawImage()
+        # returns PIL image
+        img = rdr(os.path.join(os.path.dirname(__file__), 'testimage.nef'))
+        self.assertEqual(img.size, (6016, 4016)) # FIXME: change when image was replaced
+        #self.assertEqual(img.size, (1, 1))
+        #self.assertEqual(img.getdata().getpixel((0, 0)), (0, 0, 0))
+        img.close()
+        # raises exception when image cannot be read
+        self.assertRaises(errors.ReaderError, rdr,
+            os.path.join(os.path.dirname(__file__), 'invalid.nef'))
+        self.assertRaises(errors.ReaderError, rdr,
+            os.path.join(os.path.dirname(__file__), 'testimage.jpg'))
+
+
+
+
+## main ##
+
+if __name__ == '__main__':
+    unittest.main()
+
+## EOF ##
diff --git a/test/reader/image/testimage.jpg b/test/reader/image/testimage.jpg
new file mode 100644
index 0000000..ea7af63
--- /dev/null
+++ b/test/reader/image/testimage.jpg
diff --git a/test/base/test_reader.py b/test/reader/test_base.py
index a907eb9..41f4c29 100644
--- a/test/base/test_reader.py
+++ b/test/reader/test_base.py
@@ -4,16 +4,16 @@ Part of the bsie test suite.
 A copy of the license is provided with the project.
 Author: Matthias Baumgartner, 2022
 """
-# imports
+# standard imports
 import unittest
 
 # objects to test
-from bsie import base
+from bsie.reader import Reader
 
 
 ## code ##
 
-class StubReader(base.Reader):
+class StubReader(Reader):
     def __call__(self, path):
         raise NotImplementedError()
 
diff --git a/test/reader/test_builder.py b/test/reader/test_builder.py
new file mode 100644
index 0000000..92e9edc
--- /dev/null
+++ b/test/reader/test_builder.py
@@ -0,0 +1,54 @@
+"""
+
+Part of the bsie test suite.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+import unittest
+
+# bsie imports
+from bsie.utils import errors
+
+# objects to test
+from bsie.reader import ReaderBuilder
+
+
+## code ##
+
+class TestReaderBuilder(unittest.TestCase):
+    def test_build(self):
+        builder = ReaderBuilder({'bsie.reader.path.Path': {}})
+        # build configured reader
+        cls = builder.build('bsie.reader.path.Path')
+        import bsie.reader.path
+        self.assertIsInstance(cls, bsie.reader.path.Path)
+        # build unconfigured reader
+        cls = builder.build('bsie.reader.stat.Stat')
+        import bsie.reader.stat
+        self.assertIsInstance(cls, bsie.reader.stat.Stat)
+        # re-build previous reader (test cache)
+        self.assertEqual(cls, builder.build('bsie.reader.stat.Stat'))
+        # test invalid
+        self.assertRaises(TypeError, builder.build, 123)
+        self.assertRaises(TypeError, builder.build, None)
+        self.assertRaises(ValueError, builder.build, '')
+        self.assertRaises(ValueError, builder.build, 'Path')
+        self.assertRaises(errors.BuilderError, builder.build, 'path.Path')
+        # invalid config
+        builder = ReaderBuilder({'bsie.reader.stat.Stat': dict(foo=123)})
+        self.assertRaises(errors.BuilderError, builder.build, 'bsie.reader.stat.Stat')
+        builder = ReaderBuilder({'bsie.reader.stat.Stat': 123})
+        self.assertRaises(TypeError, builder.build, 'bsie.reader.stat.Stat')
+        # no instructions
+        builder = ReaderBuilder({})
+        cls = builder.build('bsie.reader.stat.Stat')
+        self.assertIsInstance(cls, bsie.reader.stat.Stat)
+
+
+## main ##
+
+if __name__ == '__main__':
+    unittest.main()
+
+## EOF ##
diff --git a/test/reader/test_chain.py b/test/reader/test_chain.py
new file mode 100644
index 0000000..901faa1
--- /dev/null
+++ b/test/reader/test_chain.py
@@ -0,0 +1,85 @@
+"""
+
+Part of the bsie test suite.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+import logging
+import os
+import unittest
+
+# bsie imports
+from bsie.utils import errors
+import bsie.reader.path
+import bsie.reader.stat
+
+# objects to test
+from bsie.reader.chain import ReaderChain
+
+
+## code ##
+
+class TestReaderChain(unittest.TestCase):
+    def test_construct(self):
+        # subreaders are built
+        chain = ReaderChain(['bsie.reader.stat.Stat', 'bsie.reader.path.Path'], {})
+        self.assertIsInstance(chain, ReaderChain)
+        self.assertEqual(chain._children,
+            (bsie.reader.stat.Stat(), bsie.reader.path.Path()))
+        # subreaders that failed to build are omitted
+        with self.assertLogs(logging.getLogger('bsie.reader.chain'), logging.WARNING):
+            chain = ReaderChain(['bsie.reader.stat.Stat', 'bsie.reader.invalid.Invalid'], {})
+            self.assertEqual(chain._children, (bsie.reader.stat.Stat(), ))
+        with self.assertLogs(logging.getLogger('bsie.reader.chain'), logging.WARNING):
+            chain = ReaderChain(['bsie.reader.stat.Stat', 'bsie.reader.path.Invalid'], {})
+            self.assertEqual(chain._children, (bsie.reader.stat.Stat(), ))
+        # warning is issued if there are no subreaders
+        with self.assertLogs(logging.getLogger('bsie.reader.chain'), logging.WARNING):
+            chain = ReaderChain([], {})
+            self.assertEqual(chain._children, tuple())
+
+    def test_essentials(self):
+        chain = ReaderChain(['bsie.reader.stat.Stat', 'bsie.reader.path.Path'], {})
+        # identity
+        self.assertEqual(chain, chain)
+        self.assertEqual(hash(chain), hash(chain))
+        # comparison works across instances
+        self.assertEqual(chain,
+            ReaderChain(['bsie.reader.stat.Stat', 'bsie.reader.path.Path'], {}))
+        self.assertEqual(hash(chain),
+            hash(ReaderChain(['bsie.reader.stat.Stat', 'bsie.reader.path.Path'], {})))
+        # comparison respects subreaders
+        self.assertNotEqual(hash(chain),
+            hash(ReaderChain(['bsie.reader.path.Path'], {})))
+        self.assertNotEqual(hash(chain),
+            hash(ReaderChain(['bsie.reader.path.Path'], {})))
+        # comparison respects subreader order
+        self.assertNotEqual(chain,
+            ReaderChain(['bsie.reader.path.Path', 'bsie.reader.stat.Stat'], {}))
+        self.assertNotEqual(hash(chain),
+            hash(ReaderChain(['bsie.reader.path.Path', 'bsie.reader.stat.Stat'], {})))
+        # string representation
+        self.assertEqual(str(chain), 'ReaderChain(Stat, Path)')
+        self.assertEqual(repr(chain), 'ReaderChain((Stat(), Path()))')
+
+    def test_call(self):
+        chain = ReaderChain(['bsie.reader.stat.Stat', 'bsie.reader.path.Path'], {})
+        # chain first probes first child
+        self.assertEqual(chain(__file__), os.stat(__file__))
+        # chain probes second child if first one failes
+        self.assertEqual(chain(''), '')
+        self.assertEqual(chain('missing-file'), 'missing-file')
+
+        # chain raises a ReaderError if childs were exhausted
+        chain = ReaderChain(['bsie.reader.stat.Stat'], {})
+        # chain probes second child if first one failes
+        self.assertRaises(errors.ReaderError, chain, '')
+
+
+## main ##
+
+if __name__ == '__main__':
+    unittest.main()
+
+## EOF ##
diff --git a/test/reader/test_path.py b/test/reader/test_path.py
index fd7bc5a..95e447f 100644
--- a/test/reader/test_path.py
+++ b/test/reader/test_path.py
@@ -4,7 +4,7 @@ Part of the bsie test suite.
 A copy of the license is provided with the project.
 Author: Matthias Baumgartner, 2022
 """
-# imports
+# standard imports
 import unittest
 
 # objects to test
diff --git a/test/reader/test_stat.py b/test/reader/test_stat.py
index d12ad9c..fd9fdcd 100644
--- a/test/reader/test_stat.py
+++ b/test/reader/test_stat.py
@@ -4,12 +4,12 @@ Part of the bsie test suite.
 A copy of the license is provided with the project.
 Author: Matthias Baumgartner, 2022
 """
-# imports
+# standard imports
 import os
 import unittest
 
 # bsie imports
-from bsie.base import errors
+from bsie.utils import errors
 
 # objects to test
 from bsie.reader.stat import Stat
diff --git a/test/tools/test_builder.py b/test/tools/test_builder.py
deleted file mode 100644
index 62c637c..0000000
--- a/test/tools/test_builder.py
+++ /dev/null
@@ -1,246 +0,0 @@
-"""
-
-Part of the bsie test suite.
-A copy of the license is provided with the project.
-Author: Matthias Baumgartner, 2022
-"""
-# imports
-import logging
-import unittest
-
-# bsie imports
-from bsie import base
-from bsie.utils import bsfs
-
-# objects to test
-from bsie.tools.builder import ExtractorBuilder
-from bsie.tools.builder import PipelineBuilder
-from bsie.tools.builder import ReaderBuilder
-from bsie.tools.builder import _safe_load
-from bsie.tools.builder import _unpack_name
-
-
-## code ##
-
-class TestUtils(unittest.TestCase):
-    def test_safe_load(self):
-        # invalid module
-        self.assertRaises(base.errors.LoaderError, _safe_load, 'dBGHMSAYOoKeKMpywDoKZQycENFPvN', 'foobar')
-        self.assertRaises(base.errors.LoaderError, _safe_load, 'dBGHMSAYOoKeKMpywDoKZQycENFPvN.bar', 'foobar')
-        # partially valid module
-        self.assertRaises(base.errors.LoaderError, _safe_load, 'os.foo', 'foobar')
-        # invalid class
-        self.assertRaises(base.errors.LoaderError, _safe_load, 'os.path', 'foo')
-        # valid module and class
-        cls = _safe_load('collections.abc', 'Container')
-        import collections.abc
-        self.assertEqual(cls, collections.abc.Container)
-
-    def test_unpack_name(self):
-        self.assertRaises(TypeError, _unpack_name, 123)
-        self.assertRaises(TypeError, _unpack_name, None)
-        self.assertRaises(ValueError, _unpack_name, '')
-        self.assertRaises(ValueError, _unpack_name, 'path')
-        self.assertRaises(ValueError, _unpack_name, '.Path')
-        self.assertEqual(_unpack_name('path.Path'), ('path', 'Path'))
-        self.assertEqual(_unpack_name('path.foo.bar.Path'), ('path.foo.bar', 'Path'))
-
-
-class TestReaderBuilder(unittest.TestCase):
-    def test_build(self):
-        builder = ReaderBuilder({'bsie.reader.path.Path': {}})
-        # build configured reader
-        cls = builder.build('bsie.reader.path.Path')
-        import bsie.reader.path
-        self.assertIsInstance(cls, bsie.reader.path.Path)
-        # build unconfigured reader
-        cls = builder.build('bsie.reader.stat.Stat')
-        import bsie.reader.stat
-        self.assertIsInstance(cls, bsie.reader.stat.Stat)
-        # re-build previous reader (test cache)
-        self.assertEqual(cls, builder.build('bsie.reader.stat.Stat'))
-        # test invalid
-        self.assertRaises(TypeError, builder.build, 123)
-        self.assertRaises(TypeError, builder.build, None)
-        self.assertRaises(ValueError, builder.build, '')
-        self.assertRaises(ValueError, builder.build, 'Path')
-        self.assertRaises(base.errors.BuilderError, builder.build, 'path.Path')
-        # invalid config
-        builder = ReaderBuilder({'bsie.reader.stat.Stat': dict(foo=123)})
-        self.assertRaises(base.errors.BuilderError, builder.build, 'bsie.reader.stat.Stat')
-        builder = ReaderBuilder({'bsie.reader.stat.Stat': 123})
-        self.assertRaises(TypeError, builder.build, 'bsie.reader.stat.Stat')
-        # no instructions
-        builder = ReaderBuilder({})
-        cls = builder.build('bsie.reader.stat.Stat')
-        self.assertIsInstance(cls, bsie.reader.stat.Stat)
-
-
-
-class TestExtractorBuilder(unittest.TestCase):
-    def test_iter(self):
-        # no specifications
-        self.assertListEqual(list(ExtractorBuilder([])), [])
-        # some specifications
-        builder = ExtractorBuilder([
-            {'bsie.extractor.generic.path.Path': {}},
-            {'bsie.extractor.generic.stat.Stat': {}},
-            {'bsie.extractor.generic.path.Path': {}},
-            ])
-        self.assertListEqual(list(builder), [0, 1, 2])
-
-    def test_build(self):
-        # simple and repeated extractors
-        builder = ExtractorBuilder([
-            {'bsie.extractor.generic.path.Path': {}},
-            {'bsie.extractor.generic.stat.Stat': {}},
-            {'bsie.extractor.generic.path.Path': {}},
-            ])
-        ext = [builder.build(0), builder.build(1), builder.build(2)]
-        import bsie.extractor.generic.path
-        import bsie.extractor.generic.stat
-        self.assertListEqual(ext, [
-            bsie.extractor.generic.path.Path(),
-            bsie.extractor.generic.stat.Stat(),
-            bsie.extractor.generic.path.Path(),
-            ])
-        # out-of-bounds raises KeyError
-        self.assertRaises(IndexError, builder.build, 3)
-
-        # building with args
-        builder = ExtractorBuilder([
-            {'bsie.extractor.generic.constant.Constant': {
-                'schema': '''
-                    bse:author rdfs:subClassOf bsfs:Predicate ;
-                        rdfs:domain bsfs:Entity ;
-                        rdfs:range xsd:string ;
-                        bsfs:unique "true"^^xsd:boolean .
-                    bse:rating rdfs:subClassOf bsfs:Predicate ;
-                        rdfs:domain bsfs:Entity ;
-                        rdfs:range xsd:integer ;
-                        bsfs:unique "true"^^xsd:boolean .
-                    ''',
-                'tuples': [
-                    ('http://bsfs.ai/schema/Entity#author', 'Me, myself, and I'),
-                    ('http://bsfs.ai/schema/Entity#rating', 123),
-                    ],
-            }}])
-        obj = builder.build(0)
-        import bsie.extractor.generic.constant
-        self.assertEqual(obj, bsie.extractor.generic.constant.Constant('''
-                    bse:author rdfs:subClassOf bsfs:Predicate ;
-                        rdfs:domain bsfs:Entity ;
-                        rdfs:range xsd:string ;
-                        bsfs:unique "true"^^xsd:boolean .
-                    bse:rating rdfs:subClassOf bsfs:Predicate ;
-                        rdfs:domain bsfs:Entity ;
-                        rdfs:range xsd:integer ;
-                        bsfs:unique "true"^^xsd:boolean .
-                    ''', [
-            ('http://bsfs.ai/schema/Entity#author', 'Me, myself, and I'),
-            ('http://bsfs.ai/schema/Entity#rating', 123),
-            ]))
-
-        # building with invalid args
-        self.assertRaises(base.errors.BuilderError, ExtractorBuilder(
-            [{'bsie.extractor.generic.path.Path': {'foo': 123}}]).build, 0)
-        # non-dict build specification
-        self.assertRaises(TypeError, ExtractorBuilder(
-            [('bsie.extractor.generic.path.Path', {})]).build, 0)
-        # multiple keys per build specification
-        self.assertRaises(TypeError, ExtractorBuilder(
-            [{'bsie.extractor.generic.path.Path': {},
-              'bsie.extractor.generic.stat.Stat': {}}]).build, 0)
-        # non-dict value for kwargs
-        self.assertRaises(TypeError, ExtractorBuilder(
-            [{'bsie.extractor.generic.path.Path': 123}]).build, 0)
-
-
-
-
-class TestPipelineBuilder(unittest.TestCase):
-    def test_build(self):
-        prefix = bsfs.URI('http://example.com/local/file#')
-        c_schema = '''
-            bse:author rdfs:subClassOf bsfs:Predicate ;
-                rdfs:domain bsfs:Entity ;
-                rdfs:range xsd:string ;
-                bsfs:unique "true"^^xsd:boolean .
-            '''
-        c_tuples = [('http://bsfs.ai/schema/Entity#author', 'Me, myself, and I')]
-        # prepare builders
-        rbuild = ReaderBuilder({})
-        ebuild = ExtractorBuilder([
-            {'bsie.extractor.generic.path.Path': {}},
-            {'bsie.extractor.generic.stat.Stat': {}},
-            {'bsie.extractor.generic.constant.Constant': dict(
-                schema=c_schema,
-                tuples=c_tuples,
-                )},
-            ])
-        # build pipeline
-        builder = PipelineBuilder(prefix, rbuild, ebuild)
-        pipeline = builder.build()
-        # delayed import
-        import bsie.reader.path
-        import bsie.reader.stat
-        import bsie.extractor.generic.path
-        import bsie.extractor.generic.stat
-        import bsie.extractor.generic.constant
-        # check pipeline
-        self.assertDictEqual(pipeline._ext2rdr, {
-            bsie.extractor.generic.path.Path(): bsie.reader.path.Path(),
-            bsie.extractor.generic.stat.Stat(): bsie.reader.stat.Stat(),
-            bsie.extractor.generic.constant.Constant(c_schema, c_tuples): None,
-            })
-
-        # fail to load extractor
-        ebuild_err = ExtractorBuilder([
-            {'bsie.extractor.generic.foo.Foo': {}},
-            {'bsie.extractor.generic.path.Path': {}},
-            ])
-        with self.assertLogs(logging.getLogger('bsie.tools.builder'), logging.ERROR):
-            pipeline = PipelineBuilder(prefix, rbuild, ebuild_err).build()
-            self.assertDictEqual(pipeline._ext2rdr, {
-                bsie.extractor.generic.path.Path(): bsie.reader.path.Path()})
-
-        # fail to build extractor
-        ebuild_err = ExtractorBuilder([
-            {'bsie.extractor.generic.path.Path': {'foo': 123}},
-            {'bsie.extractor.generic.path.Path': {}},
-            ])
-        with self.assertLogs(logging.getLogger('bsie.tools.builder'), logging.ERROR):
-            pipeline = PipelineBuilder(prefix, rbuild, ebuild_err).build()
-            self.assertDictEqual(pipeline._ext2rdr, {
-                bsie.extractor.generic.path.Path(): bsie.reader.path.Path()})
-
-        # fail to load reader
-        with self.assertLogs(logging.getLogger('bsie.tools.builder'), logging.ERROR):
-            # switch reader of an extractor
-            old_reader = bsie.extractor.generic.path.Path.CONTENT_READER
-            bsie.extractor.generic.path.Path.CONTENT_READER = 'bsie.reader.foo.Foo'
-            # build pipeline with invalid reader reference
-            pipeline = PipelineBuilder(prefix, rbuild, ebuild).build()
-            self.assertDictEqual(pipeline._ext2rdr, {
-                bsie.extractor.generic.stat.Stat(): bsie.reader.stat.Stat(),
-                bsie.extractor.generic.constant.Constant(c_schema, c_tuples): None,
-                })
-            # switch back
-            bsie.extractor.generic.path.Path.CONTENT_READER = old_reader
-
-        # fail to build reader
-        rbuild_err = ReaderBuilder({'bsie.reader.stat.Stat': dict(foo=123)})
-        with self.assertLogs(logging.getLogger('bsie.tools.builder'), logging.ERROR):
-            pipeline = PipelineBuilder(prefix, rbuild_err, ebuild).build()
-            self.assertDictEqual(pipeline._ext2rdr, {
-                bsie.extractor.generic.path.Path(): bsie.reader.path.Path(),
-                bsie.extractor.generic.constant.Constant(c_schema, c_tuples): None,
-                })
-
-
-## main ##
-
-if __name__ == '__main__':
-    unittest.main()
-
-## EOF ##
diff --git a/test/tools/testfile.t b/test/tools/testfile.t
deleted file mode 100644
index 3b18e51..0000000
--- a/test/tools/testfile.t
+++ /dev/null
@@ -1 +0,0 @@
-hello world
diff --git a/test/utils/filematcher/__init__.py b/test/utils/filematcher/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/test/utils/filematcher/__init__.py
diff --git a/test/utils/filematcher/empty b/test/utils/filematcher/empty
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/test/utils/filematcher/empty
diff --git a/test/utils/filematcher/test_matcher.py b/test/utils/filematcher/test_matcher.py
new file mode 100644
index 0000000..c3cccee
--- /dev/null
+++ b/test/utils/filematcher/test_matcher.py
@@ -0,0 +1,232 @@
+"""
+
+Part of the bsie test suite.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+import os
+import stat
+import tempfile
+import unittest
+
+# objects to test
+from bsie.utils.filematcher import matcher
+
+
+## code ##
+
+class FakeMatcher(matcher.Matcher):
+    def __call__(self, *args, **kwargs):
+        pass
+
+class FakeCriterion(matcher.Criterion):
+    def __call__(self, *args, **kwargs):
+        pass
+
+class FakeAggregate(matcher.Aggregate):
+    def __call__(self, *args, **kwargs):
+        pass
+
+class TestMatcher(unittest.TestCase):
+    def setUp(self):
+        # paths
+        self.image = os.path.join(os.path.dirname(__file__), 'testimage.jpg')
+        self.text= os.path.join(os.path.dirname(__file__), 'textfile.t')
+        self.empty = os.path.join(os.path.dirname(__file__), 'empty')
+        self.missing = os.path.join(os.path.dirname(__file__), 'missing.jpg')
+
+    def test_matcher_skeleton(self):
+        # node: iteration and length
+        self.assertSetEqual(set(iter(FakeMatcher(1,2,3))), {1,2,3})
+        self.assertSetEqual(set(iter(FakeMatcher([1,2,3]))), {1,2,3})
+        self.assertEqual(len(FakeMatcher([1,2,3])), 3)
+        self.assertEqual(len(FakeMatcher(1,2,3)), 3)
+        self.assertEqual(len(FakeMatcher()), 0)
+        self.assertIn(1, FakeMatcher(1,2,3))
+        self.assertIn(3, FakeMatcher([1,2,3]))
+        self.assertNotIn(0, FakeMatcher(1,2,3))
+        self.assertNotIn(4, FakeMatcher([1,2,3]))
+        # node: comparison
+        self.assertEqual(FakeMatcher([1,2,3]), FakeMatcher([1,2,3]))
+        self.assertEqual(FakeMatcher(1,2,3), FakeMatcher(1,2,3))
+        self.assertEqual(FakeMatcher(1,2,3), FakeMatcher([1,2,3]))
+        self.assertEqual(FakeMatcher(1,2,3), FakeMatcher((1,2,3)))
+        self.assertNotEqual(FakeMatcher(1,2,3), FakeMatcher(1,2,4))
+        self.assertNotEqual(FakeMatcher(1,2,3), FakeMatcher(1,2,3,4))
+        self.assertNotEqual(FakeMatcher(1,2,3), FakeMatcher(1,2))
+        self.assertEqual(hash(FakeMatcher([1,2,3])), hash(FakeMatcher([1,2,3])))
+        self.assertEqual(hash(FakeMatcher(1,2,3)), hash(FakeMatcher(1,2,3)))
+        self.assertEqual(hash(FakeMatcher(1,2,3)), hash(FakeMatcher([1,2,3])))
+        self.assertEqual(hash(FakeMatcher(1,2,3)), hash(FakeMatcher((1,2,3))))
+        # node: representation
+        self.assertEqual(repr(FakeMatcher(1,2,3)), 'FakeMatcher({1, 2, 3})')
+
+        # criterion
+        self.assertEqual(repr(FakeCriterion(1,2,3)), 'FakeCriterion({1, 2, 3})')
+        self.assertEqual(hash(FakeCriterion(1,2,3)), hash(FakeCriterion(1,2,3)))
+        self.assertEqual(FakeCriterion(1,2,3), FakeCriterion([1,2,3]))
+        self.assertNotEqual(FakeCriterion(1,2,3), FakeCriterion(1,2))
+        self.assertNotEqual(FakeCriterion(1,2,3), FakeMatcher(1,2,3))
+        self.assertSetEqual(FakeCriterion(1,2,3).accepted(), {1,2,3})
+
+        # aggregate
+        self.assertEqual(repr(FakeAggregate(1,2,3)), 'FakeAggregate({1, 2, 3})')
+        self.assertNotEqual(FakeAggregate(1,2,3), FakeMatcher(1,2,3))
+
+    def test_any(self):
+        self.assertTrue(matcher.Any()(self.image))
+        self.assertTrue(matcher.Any()(self.text))
+        self.assertTrue(matcher.Any()(self.missing))
+        self.assertTrue(matcher.Any()(self.empty))
+
+    def test_nothing(self):
+        self.assertFalse(matcher.Nothing()(self.image))
+        self.assertFalse(matcher.Nothing()(self.text))
+        self.assertFalse(matcher.Nothing()(self.missing))
+        self.assertFalse(matcher.Nothing()(self.empty))
+
+    def test_exists(self):
+        self.assertTrue(matcher.Exists()(self.image))
+        self.assertTrue(matcher.Exists()(self.text))
+        self.assertTrue(matcher.Exists()(self.empty))
+        self.assertFalse(matcher.Exists()(self.missing))
+
+    def test_isfile(self):
+        self.assertTrue(matcher.IsFile()(self.image))
+        self.assertTrue(matcher.IsFile()(self.text))
+        self.assertFalse(matcher.IsFile()(self.missing))
+        self.assertFalse(matcher.IsFile()(os.path.dirname(self.image)))
+
+    def test_isdir(self):
+        self.assertTrue(matcher.IsDir()(os.path.dirname(self.image)))
+        self.assertFalse(matcher.IsDir()(self.image))
+        self.assertFalse(matcher.IsDir()(self.text))
+        self.assertFalse(matcher.IsDir()(self.missing))
+
+    def test_islink(self):
+        self.assertFalse(matcher.IsLink()(os.path.dirname(self.image)))
+        self.assertFalse(matcher.IsLink()(self.image))
+        self.assertFalse(matcher.IsLink()(self.text))
+        _, temp = tempfile.mkstemp(prefix='bsie-test-')
+        templink = temp + '-link'
+        os.symlink(temp, templink)
+        self.assertTrue(matcher.IsLink()(templink))
+        os.unlink(templink)
+        os.unlink(temp)
+
+    def test_isabs(self):
+        self.assertTrue(matcher.IsAbs()(os.path.abspath(self.image)))
+        self.assertTrue(matcher.IsAbs()(os.path.abspath(self.text)))
+        self.assertFalse(matcher.IsAbs()(os.path.relpath(self.text, os.path.dirname(self.text))))
+
+    def test_isrel(self):
+        self.assertFalse(matcher.IsRel()(os.path.abspath(self.image)))
+        self.assertFalse(matcher.IsRel()(os.path.abspath(self.text)))
+        self.assertTrue(matcher.IsRel()(os.path.relpath(self.text, os.path.dirname(self.text))))
+        self.assertTrue(matcher.IsRel()(os.path.basename(self.text)))
+
+    def test_ismount(self):
+        self.assertFalse(matcher.IsMount()(self.image))
+        self.assertFalse(matcher.IsMount()(self.text))
+        self.assertFalse(matcher.IsMount()(self.missing))
+        # there's no reasonable way to test a positive case
+
+    def test_isempty(self):
+        self.assertTrue(matcher.IsEmpty()(self.empty))
+        self.assertFalse(matcher.IsEmpty()(self.image))
+        self.assertFalse(matcher.IsEmpty()(self.text))
+        self.assertFalse(matcher.IsEmpty()(self.missing))
+
+    def test_isreadable(self):
+        self.assertTrue(matcher.IsReadable()(self.empty))
+        self.assertTrue(matcher.IsReadable()(self.image))
+        self.assertFalse(matcher.IsReadable()(self.missing))
+        _, temp = tempfile.mkstemp(prefix='bsie-test-')
+        os.chmod(temp, 0)
+        self.assertFalse(matcher.IsReadable()(temp))
+        os.unlink(temp)
+
+    def test_iswritable(self):
+        self.assertTrue(matcher.IsWritable()(self.empty))
+        self.assertTrue(matcher.IsWritable()(self.image))
+        self.assertFalse(matcher.IsWritable()(self.missing))
+        _, temp = tempfile.mkstemp(prefix='bsie-test-')
+        os.chmod(temp, 0)
+        self.assertFalse(matcher.IsWritable()(temp))
+        os.unlink(temp)
+
+    def test_isexecutable(self):
+        self.assertFalse(matcher.IsExecutable()(self.empty))
+        self.assertFalse(matcher.IsExecutable()(self.image))
+        self.assertFalse(matcher.IsExecutable()(self.missing))
+        _, temp = tempfile.mkstemp(prefix='bsie-test-')
+        os.chmod(temp, stat.S_IEXEC)
+        self.assertTrue(matcher.IsExecutable()(temp))
+        os.unlink(temp)
+
+    def test_extension(self):
+        self.assertTrue(matcher.Extension('jpg')(self.image))
+        self.assertTrue(matcher.Extension('jpg', 'png')(self.image))
+        self.assertTrue(matcher.Extension('jpg', 't')(self.text))
+        self.assertTrue(matcher.Extension('jpg', 'png', 't')(self.missing))
+        self.assertTrue(matcher.Extension('')(self.empty))
+
+        self.assertFalse(matcher.Extension()(self.image))
+        self.assertFalse(matcher.Extension('jpeg')(self.image))
+        self.assertFalse(matcher.Extension('.t')(self.text))
+        self.assertFalse(matcher.Extension('png', 't')(self.missing))
+        self.assertFalse(matcher.Extension('tiff')(self.empty))
+
+    def test_mime(self):
+        self.assertTrue(matcher.Mime('image/jpeg')(self.image))
+        self.assertTrue(matcher.Mime('image/tiff', 'image/jpeg')(self.image))
+        self.assertTrue(matcher.Mime('text/plain', 'image/jpeg')(self.text))
+        self.assertTrue(matcher.Mime('inode/x-empty')(self.empty))
+
+        self.assertFalse(matcher.Mime()(self.image))
+        self.assertFalse(matcher.Mime('image')(self.image))
+        self.assertFalse(matcher.Mime('image/tiff', 'image/png')(self.image))
+        self.assertFalse(matcher.Mime('')(self.text))
+        self.assertFalse(matcher.Mime('text')(self.text))
+        self.assertFalse(matcher.Mime('tiff')(self.empty))
+        self.assertFalse(matcher.Mime()(self.empty))
+        self.assertFalse(matcher.Mime('')(self.empty))
+        self.assertFalse(matcher.Mime()(self.missing))
+        self.assertFalse(matcher.Mime('')(self.missing))
+        self.assertFalse(matcher.Mime('inode/x-empty')(self.missing))
+
+    def test_not(self):
+        self.assertFalse(matcher.NOT(matcher.Mime('image/jpeg'))(self.image))
+        self.assertTrue(matcher.NOT(matcher.Mime('text/plain'))(self.image))
+
+    def test_and(self):
+        self.assertTrue(matcher.And(matcher.Mime('image/jpeg'), matcher.Extension('jpg'))(self.image))
+        self.assertTrue(matcher.And(matcher.Mime('image/jpeg'), matcher.Extension('jpg', 'tiff'))(self.image))
+        self.assertTrue(matcher.And(matcher.Mime('text/plain'), matcher.Extension('t', 'tiff'))(self.text))
+
+        self.assertFalse(matcher.And(matcher.Mime('image/jpeg'), matcher.Extension('tiff'))(self.image))
+        self.assertFalse(matcher.And(matcher.Mime('text/plain'), matcher.Extension('jpg'))(self.image))
+        self.assertFalse(matcher.And(matcher.Mime('inode/x-empty'), matcher.Extension('jpg'))(self.missing))
+        self.assertFalse(matcher.And(matcher.Mime('image/jpeg'), matcher.Extension('jpg', 't'))(self.text))
+
+    def test_or(self):
+        self.assertTrue(matcher.Or(matcher.Mime('image/jpeg'))(self.image))
+        self.assertFalse(matcher.Or(matcher.Mime('text/plain'))(self.image))
+
+        self.assertTrue(matcher.Or(matcher.Mime('image/jpeg'), matcher.Extension('jpg'))(self.image))
+        self.assertTrue(matcher.Or(matcher.Mime('image/jpeg'), matcher.Extension('t'))(self.image))
+        self.assertTrue(matcher.Or(matcher.Mime('text/plain'), matcher.Extension('jpg', 'tiff'))(self.image))
+        self.assertTrue(matcher.Or(matcher.Mime('text/plain'), matcher.Extension('tiff'))(self.text))
+        self.assertTrue(matcher.Or(matcher.Mime('image/jpeg'), matcher.Extension('jpg'))(self.missing))
+
+        self.assertFalse(matcher.Or(matcher.Mime('text/plain'), matcher.Extension('tiff'))(self.image))
+        self.assertFalse(matcher.Or(matcher.Mime('inode/x-empty'), matcher.Extension('jpg', 'tiff'))(self.text))
+
+
+## main ##
+
+if __name__ == '__main__':
+    unittest.main()
+
+## EOF ##
diff --git a/test/utils/filematcher/test_parser.py b/test/utils/filematcher/test_parser.py
new file mode 100644
index 0000000..c594747
--- /dev/null
+++ b/test/utils/filematcher/test_parser.py
@@ -0,0 +1,146 @@
+"""
+
+Part of the bsie test suite.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+import unittest
+
+# bsie imports
+from bsie.utils import errors
+from bsie.utils.filematcher import matcher
+
+# objects to test
+from bsie.utils.filematcher import parse
+
+
+## code ##
+
+class TestFileMatcherParser(unittest.TestCase):
+    def test_empty(self):
+        # no criterion
+        self.assertEqual(parse(''), matcher.Any())
+
+    def test_ruleone(self):
+        # single criterion, single value
+        self.assertEqual(parse('mime=text'), matcher.Mime('text'))
+        self.assertEqual(parse('MIME=text'), matcher.Mime('text'))
+        self.assertEqual(parse('MiMe=text'), matcher.Mime('text'))
+        self.assertEqual(parse('MIME=TEXT'), matcher.Mime('TEXT'))
+        self.assertEqual(parse('mime={text}'), matcher.Mime('text'))
+        self.assertEqual(parse('mime=image/jpeg'), matcher.Mime('image/jpeg'))
+        self.assertEqual(parse('mime="image/jpeg"'), matcher.Mime('image/jpeg'))
+        self.assertEqual(parse('extension=pdf'), matcher.Extension('pdf'))
+        self.assertEqual(parse('extension={pdf}'), matcher.Extension('pdf'))
+        self.assertEqual(parse('extension="pdf"'), matcher.Extension('pdf'))
+        self.assertEqual(parse('extension="foo,bar"'), matcher.Extension('foo,bar'))
+        self.assertEqual(parse('extension="f{oo|ba}r"'), matcher.Extension('f{oo|ba}r'))
+        self.assertEqual(parse('extension=""'), matcher.Extension(''))
+        self.assertEqual(parse('extension="foo'), matcher.Extension('"foo'))
+        self.assertRaises(errors.ParserError, parse, 'extension=foo=bar')
+        self.assertRaises(errors.ParserError, parse, 'extension=')
+        self.assertRaises(errors.ParserError, parse, 'extension={}')
+        self.assertRaises(errors.ParserError, parse, 'extension={foo')
+
+        # valueless
+        self.assertEqual(parse('any'), matcher.Any())
+        self.assertEqual(parse('nothing'), matcher.Nothing())
+        self.assertEqual(parse('exists'), matcher.Exists())
+        self.assertEqual(parse('any, nothing'), matcher.And(matcher.Any(), matcher.Nothing()))
+        self.assertEqual(parse('any, nothing, exists'),
+            matcher.And(matcher.Any(), matcher.Nothing(), matcher.Exists()))
+        self.assertEqual(parse('any, extension=jpg'), matcher.And(matcher.Any(), matcher.Extension('jpg')))
+        self.assertRaises(errors.ParserError, parse, 'mime')
+        self.assertRaises(errors.ParserError, parse, 'extension')
+        self.assertRaises(errors.ParserError, parse, 'exists=True')
+        self.assertRaises(errors.ParserError, parse, 'exists=foo')
+        self.assertEqual(parse('!any'), matcher.NOT(matcher.Any()))
+        self.assertEqual(parse('!any, nothing'), matcher.And(matcher.NOT(matcher.Any()), matcher.Nothing()))
+        self.assertEqual(parse('!any, extension=jpg'),
+            matcher.And(matcher.NOT(matcher.Any()), matcher.Extension('jpg')))
+        self.assertRaises(errors.ParserError, parse, '!mime')
+        self.assertRaises(errors.ParserError, parse, '!extension')
+
+    def test_rulefew(self):
+        # single criterion, multiple values
+        self.assertEqual(parse('extension={jpg, jpeg}'), matcher.Extension('jpg', 'jpeg'))
+        self.assertEqual(parse('mime={image/jpeg, image/png}'),
+            matcher.Mime('image/jpeg', 'image/png'))
+        self.assertRaises(errors.ParserError, parse, 'mime=image/png, image/jpeg')
+        self.assertRaises(errors.ParserError, parse, 'extension=jpg, jpeg')
+
+    def test_rulesets_ruleone(self):
+        # mutliple criteria, single value
+        self.assertEqual(parse('mime=text, extension=t'),
+            matcher.And(matcher.Mime('text'), matcher.Extension('t')))
+        self.assertEqual(parse('mime=text/plain, extension=t'),
+            matcher.And(matcher.Mime('text/plain'), matcher.Extension('t')))
+        self.assertRaises(errors.ParserError, parse, 'mime=text/plain extension=t')
+        self.assertRaises(errors.ParserError, parse, 'mime={image/jpeg, extension=jpg'),
+
+    def test_rulesets_rulefew(self):
+        # multiple criteria, multiple values
+        self.assertEqual(parse('mime=image/jpeg, extension={jpg, jpeg}'),
+            matcher.And(matcher.Mime('image/jpeg'), matcher.Extension('jpg', 'jpeg')))
+        self.assertEqual(parse('mime={image/jpeg, image/tiff}, extension={jpg, jpeg}'),
+            matcher.And(matcher.Mime('image/jpeg', 'image/tiff'), matcher.Extension('jpg', 'jpeg')))
+        self.assertEqual(parse('mime={image/jpeg, image/tiff}, extension=jpg'),
+            matcher.And(matcher.Mime('image/jpeg', 'image/tiff'), matcher.Extension('jpg')))
+        self.assertRaises(errors.ParserError, parse, 'mime={image/jpeg, image/tiff, extension=jpg')
+        self.assertRaises(errors.ParserError, parse, 'mime=image/jpeg, image/tiff, extension=jpg')
+        self.assertRaises(errors.ParserError, parse, 'mime=image/jpeg, extension=jpg, ')
+
+    def test_not(self):
+        self.assertEqual(parse('extension!=jpg'), matcher.NOT(matcher.Extension('jpg')))
+        self.assertEqual(parse('extension!={jpg, jpeg}'),
+            matcher.NOT(matcher.Extension('jpg', 'jpeg')))
+        self.assertEqual(parse('extension!=jpg, mime=image/jpeg'),
+            matcher.And(matcher.NOT(matcher.Extension('jpg')), matcher.Mime('image/jpeg')))
+        self.assertEqual(parse('extension!=jpg, mime!=image/jpeg'),
+            matcher.And(matcher.NOT(matcher.Extension('jpg')), matcher.NOT(matcher.Mime('image/jpeg'))))
+        self.assertEqual(parse('extension!=jpg | mime=image/jpeg'),
+            matcher.Or(matcher.NOT(matcher.Extension('jpg')), matcher.Mime('image/jpeg')))
+        self.assertEqual(parse('extension!=jpg | mime!=image/jpeg'),
+            matcher.Or(matcher.NOT(matcher.Extension('jpg')), matcher.NOT(matcher.Mime('image/jpeg'))))
+
+    def test_expr(self):
+        # multiple rulesets
+        self.assertEqual(parse('mime=image/jpeg | extension=jpg'),
+            matcher.Or(matcher.Mime('image/jpeg'), matcher.Extension('jpg')))
+        self.assertEqual(parse('mime=image/jpeg | extension={jpg, jpeg}'),
+            matcher.Or(matcher.Mime('image/jpeg'), matcher.Extension('jpg', 'jpeg')))
+        self.assertEqual(parse('mime={image/jpeg, image/png} | extension={jpg, jpeg}'),
+            matcher.Or(matcher.Mime('image/jpeg', 'image/png'), matcher.Extension('jpg', 'jpeg')))
+        self.assertEqual(parse('mime=image/jpeg , extension=jpg | extension=jpg'),
+            matcher.Or(matcher.And(matcher.Mime('image/jpeg'), matcher.Extension('jpg')), matcher.Extension('jpg')))
+        self.assertEqual(parse(
+            'mime={jpeg, text}, extension={jpg,t} | extension={png,txt}, mime={png, tiff}'),
+            matcher.Or(
+                matcher.And(matcher.Mime('jpeg', 'text'), matcher.Extension('jpg', 't')),
+                matcher.And(matcher.Extension('png', 'txt'), matcher.Mime('png', 'tiff'))))
+        self.assertEqual(parse('mime=text | extension=jpg | extension=png | mime=png'),
+            matcher.Or(matcher.Mime('text'), matcher.Extension('jpg'), matcher.Extension('png'), matcher.Mime('png')))
+        self.assertRaises(errors.ParserError, parse, 'mime=text |')
+        self.assertRaises(errors.ParserError, parse, '| mime=text')
+        self.assertRaises(errors.ParserError, parse, 'extension=png | mime=text, ')
+
+    def test_invalid(self):
+        # Invalid parses
+        self.assertRaises(errors.ParserError, parse, "extension=") # Empty value
+        self.assertRaises(errors.ParserError, parse, "mime=foo,bar") # Escaping
+        self.assertRaises(errors.ParserError, parse, "mime='foo,bar") # Quoting
+        self.assertRaises(errors.ParserError, parse, "mime=\"foo,bar") # Quoting
+
+        # Invalid input
+        self.assertRaises(AttributeError, parse, None)
+        self.assertRaises(AttributeError, parse, 123)
+        self.assertRaises(AttributeError, parse, [123,321])
+
+
+## main ##
+
+if __name__ == '__main__':
+    unittest.main()
+
+## EOF ##
diff --git a/test/utils/filematcher/testimage.jpg b/test/utils/filematcher/testimage.jpg
new file mode 100644
index 0000000..ea7af63
--- /dev/null
+++ b/test/utils/filematcher/testimage.jpg
diff --git a/test/utils/filematcher/textfile.t b/test/utils/filematcher/textfile.t
new file mode 100644
index 0000000..c389011
--- /dev/null
+++ b/test/utils/filematcher/textfile.t
@@ -0,0 +1,4 @@
+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.
+Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
diff --git a/test/utils/test_loading.py b/test/utils/test_loading.py
new file mode 100644
index 0000000..58ff166
--- /dev/null
+++ b/test/utils/test_loading.py
@@ -0,0 +1,48 @@
+"""
+
+Part of the bsie test suite.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+import unittest
+
+# bsie imports
+from bsie.utils import errors
+
+# objects to test
+from bsie.utils.loading import safe_load, unpack_qualified_name
+
+
+## code ##
+
+class TestUtils(unittest.TestCase):
+    def test_safe_load(self):
+        # invalid module
+        self.assertRaises(errors.LoaderError, safe_load, 'dBGHMSAYOoKeKMpywDoKZQycENFPvN', 'foobar')
+        self.assertRaises(errors.LoaderError, safe_load, 'dBGHMSAYOoKeKMpywDoKZQycENFPvN.bar', 'foobar')
+        # partially valid module
+        self.assertRaises(errors.LoaderError, safe_load, 'os.foo', 'foobar')
+        # invalid class
+        self.assertRaises(errors.LoaderError, safe_load, 'os.path', 'foo')
+        # valid module and class
+        cls = safe_load('collections.abc', 'Container')
+        import collections.abc
+        self.assertEqual(cls, collections.abc.Container)
+
+    def test_unpack_qualified_name(self):
+        self.assertRaises(TypeError, unpack_qualified_name, 123)
+        self.assertRaises(TypeError, unpack_qualified_name, None)
+        self.assertRaises(ValueError, unpack_qualified_name, '')
+        self.assertRaises(ValueError, unpack_qualified_name, 'path')
+        self.assertRaises(ValueError, unpack_qualified_name, '.Path')
+        self.assertEqual(unpack_qualified_name('path.Path'), ('path', 'Path'))
+        self.assertEqual(unpack_qualified_name('path.foo.bar.Path'), ('path.foo.bar', 'Path'))
+
+
+## main ##
+
+if __name__ == '__main__':
+    unittest.main()
+
+## EOF ##
diff --git a/test/utils/test_node.py b/test/utils/test_node.py
index c70f0b8..9feb051 100644
--- a/test/utils/test_node.py
+++ b/test/utils/test_node.py
@@ -4,7 +4,7 @@ Part of the bsie test suite.
 A copy of the license is provided with the project.
 Author: Matthias Baumgartner, 2022
 """
-# imports
+# standard imports
 import unittest
 
 # bsie imports