diff --git a/test/_common.py b/test/_common.py
index 2f230c304..ab73481c3 100644
--- a/test/_common.py
+++ b/test/_common.py
@@ -123,9 +123,30 @@ def import_session(lib=None, loghandler=None, paths=[], query=[], cli=False):
     return cls(lib, loghandler, paths, query)
 
 
+class Assertions(object):
+    """A mixin with additional unit test assertions."""
+
+    def assertExists(self, path):  # noqa
+        self.assertTrue(os.path.exists(path),
+                        u'file does not exist: {!r}'.format(path))
+
+    def assertNotExists(self, path):  # noqa
+        self.assertFalse(os.path.exists(path),
+                         u'file exists: {!r}'.format((path)))
+
+    def assert_equal_path(self, a, b):
+        """Check that two paths are equal."""
+        # The common case.
+        if a == b:
+            return
+
+        self.assertEqual(util.normpath(a), util.normpath(b),
+                         u'paths are not equal: {!r} and {!r}'.format(a, b))
+
+
 # A test harness for all beets tests.
 # Provides temporary, isolated configuration.
-class TestCase(unittest.TestCase):
+class TestCase(unittest.TestCase, Assertions):
     """A unittest.TestCase subclass that saves and restores beets'
     global configuration. This allows tests to make temporary
     modifications that will then be automatically removed when the test
@@ -164,23 +185,6 @@ class TestCase(unittest.TestCase):
         beets.config.clear()
         beets.config._materialized = False
 
-    def assertExists(self, path):  # noqa
-        self.assertTrue(os.path.exists(path),
-                        u'file does not exist: {!r}'.format(path))
-
-    def assertNotExists(self, path):  # noqa
-        self.assertFalse(os.path.exists(path),
-                         u'file exists: {!r}'.format((path)))
-
-    def assert_equal_path(self, a, b):
-        """Check that two paths are equal."""
-        # The common case.
-        if a == b:
-            return
-
-        self.assertEqual(util.normpath(a), util.normpath(b),
-                         u'paths not equal: {!r} and {!r}'.format(a, b))
-
 
 class LibTestCase(TestCase):
     """A test case that includes an in-memory library object (`lib`) and
diff --git a/test/test_ui.py b/test/test_ui.py
index c8b6a99d3..ca3c6cbdf 100644
--- a/test/test_ui.py
+++ b/test/test_ui.py
@@ -635,7 +635,7 @@ class InputTest(_common.TestCase):
 
 
 @_common.slow_test()
-class ConfigTest(unittest.TestCase, TestHelper):
+class ConfigTest(unittest.TestCase, TestHelper, _common.Assertions):
     def setUp(self):
         self.setup_beets()
 
@@ -821,10 +821,14 @@ class ConfigTest(unittest.TestCase, TestHelper):
             file.write('statefile: state')
 
         ui._raw_main(['--config', cli_config_path, 'test'])
-        self.assertEqual(config['library'].as_filename(),
-                         os.path.join(self.user_config_dir, 'beets.db'))
-        self.assertEqual(config['statefile'].as_filename(),
-                         os.path.join(self.user_config_dir, 'state'))
+        self.assert_equal_path(
+            config['library'].as_filename(),
+            os.path.join(self.user_config_dir, 'beets.db')
+        )
+        self.assert_equal_path(
+            config['statefile'].as_filename(),
+            os.path.join(self.user_config_dir, 'state')
+        )
 
     def test_cli_config_paths_resolve_relative_to_beetsdir(self):
         os.environ['BEETSDIR'] = self.beetsdir
@@ -835,16 +839,16 @@ class ConfigTest(unittest.TestCase, TestHelper):
             file.write('statefile: state')
 
         ui._raw_main(['--config', cli_config_path, 'test'])
-        self.assertEqual(config['library'].as_filename(),
-                         os.path.join(self.beetsdir, 'beets.db'))
-        self.assertEqual(config['statefile'].as_filename(),
-                         os.path.join(self.beetsdir, 'state'))
+        self.assert_equal_path(config['library'].as_filename(),
+                               os.path.join(self.beetsdir, 'beets.db'))
+        self.assert_equal_path(config['statefile'].as_filename(),
+                               os.path.join(self.beetsdir, 'state'))
 
     def test_command_line_option_relative_to_working_dir(self):
         os.chdir(self.temp_dir)
         ui._raw_main(['--library', 'foo.db', 'test'])
-        self.assertEqual(config['library'].as_filename(),
-                         os.path.join(os.getcwd(), 'foo.db'))
+        self.assert_equal_path(config['library'].as_filename(),
+                               os.path.join(os.getcwd(), 'foo.db'))
 
     def test_cli_config_file_loads_plugin_commands(self):
         plugin_path = os.path.join(_common.RSRC, 'beetsplug')