Add proper tests to importstring.

IPython/utils/tests/test_importstring.py

@@ -0,0 +1,39 b''
+"""Tests for IPython.utils.importstring."""
+
+#-----------------------------------------------------------------------------
+#  Copyright (C) 2013  The IPython Development Team
+#
+#  Distributed under the terms of the BSD License.  The full license is in
+#  the file COPYING, distributed as part of this software.
+#-----------------------------------------------------------------------------
+
+#-----------------------------------------------------------------------------
+# Imports
+#-----------------------------------------------------------------------------
+
+import nose.tools as nt
+
+from IPython.utils.importstring import import_item
+
+#-----------------------------------------------------------------------------
+# Tests
+#-----------------------------------------------------------------------------
+
+def test_import_plain():
+    "Test simple imports"
+    import os
+    os2 = import_item('os')
+    nt.assert_is(os, os2)
+
+
+def test_import_nested():
+    "Test nested imports from the stdlib"
+    from os import path
+    path2 = import_item('os.path')
+    nt.assert_is(path, path2)
+
+
+def test_import_raises():
+    "Test that failing imports raise the right exception"
+    nt.assert_raises(ImportError, import_item, 'IPython.foobar')
+