1 files changed, 106 insertions, 0 deletions
diff --git a/lib/testtools/testtools/tests/test_helpers.py b/lib/testtools/testtools/tests/test_helpers.py
new file mode 100644
index 0000000000..f1894a4613
--- /dev/null
+++ b/lib/testtools/testtools/tests/test_helpers.py
@@ -0,0 +1,106 @@
+# Copyright (c) 2010 Jonathan M. Lange. See LICENSE for details.
+
+from testtools import TestCase
+from testtools.helpers import (
+    try_import,
+    try_imports,
+    )
+from testtools.matchers import (
+    Equals,
+    Is,
+    )
+
+
+class TestTryImport(TestCase):
+
+    def test_doesnt_exist(self):
+        # try_import('thing', foo) returns foo if 'thing' doesn't exist.
+        marker = object()
+        result = try_import('doesntexist', marker)
+        self.assertThat(result, Is(marker))
+
+    def test_None_is_default_alternative(self):
+        # try_import('thing') returns None if 'thing' doesn't exist.
+        result = try_import('doesntexist')
+        self.assertThat(result, Is(None))
+
+    def test_existing_module(self):
+        # try_import('thing', foo) imports 'thing' and returns it if it's a
+        # module that exists.
+        result = try_import('os', object())
+        import os
+        self.assertThat(result, Is(os))
+
+    def test_existing_submodule(self):
+        # try_import('thing.another', foo) imports 'thing' and returns it if
+        # it's a module that exists.
+        result = try_import('os.path', object())
+        import os
+        self.assertThat(result, Is(os.path))
+
+    def test_nonexistent_submodule(self):
+        # try_import('thing.another', foo) imports 'thing' and returns foo if
+        # 'another' doesn't exist.
+        marker = object()
+        result = try_import('os.doesntexist', marker)
+        self.assertThat(result, Is(marker))
+
+    def test_object_from_module(self):
+        # try_import('thing.object') imports 'thing' and returns
+        # 'thing.object' if 'thing' is a module and 'object' is not.
+        result = try_import('os.path.join')
+        import os
+        self.assertThat(result, Is(os.path.join))
+
+
+class TestTryImports(TestCase):
+
+    def test_doesnt_exist(self):
+        # try_imports('thing', foo) returns foo if 'thing' doesn't exist.
+        marker = object()
+        result = try_imports(['doesntexist'], marker)
+        self.assertThat(result, Is(marker))
+
+    def test_fallback(self):
+        result = try_imports(['doesntexist', 'os'])
+        import os
+        self.assertThat(result, Is(os))
+
+    def test_None_is_default_alternative(self):
+        # try_imports('thing') returns None if 'thing' doesn't exist.
+        e = self.assertRaises(
+            ImportError, try_imports, ['doesntexist', 'noreally'])
+        self.assertThat(
+            str(e),
+            Equals("Could not import any of: doesntexist, noreally"))
+
+    def test_existing_module(self):
+        # try_imports('thing', foo) imports 'thing' and returns it if it's a
+        # module that exists.
+        result = try_imports(['os'], object())
+        import os
+        self.assertThat(result, Is(os))
+
+    def test_existing_submodule(self):
+        # try_imports('thing.another', foo) imports 'thing' and returns it if
+        # it's a module that exists.
+        result = try_imports(['os.path'], object())
+        import os
+        self.assertThat(result, Is(os.path))
+
+    def test_nonexistent_submodule(self):
+        # try_imports('thing.another', foo) imports 'thing' and returns foo if
+        # 'another' doesn't exist.
+        marker = object()
+        result = try_imports(['os.doesntexist'], marker)
+        self.assertThat(result, Is(marker))
+
+    def test_fallback_submodule(self):
+        result = try_imports(['os.doesntexist', 'os.path'])
+        import os
+        self.assertThat(result, Is(os.path))
+
+
+def test_suite():
+    from unittest import TestLoader
+    return TestLoader().loadTestsFromName(__name__)