test widget link argument validation

IPython/html/widgets/tests/test_link.py

@@ -0,0 +1,39 @@
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+import nose.tools as nt
+
+from .. import link, dlink, ToggleButton
+from .test_interaction import setup, teardown
+
+def test_link_args():
+    with nt.assert_raises(TypeError):
+        link()
+    w1 = ToggleButton()
+    with nt.assert_raises(TypeError):
+        link((w1, 'value'))
+    
+    w2 = ToggleButton()
+    link((w1, 'value'), (w2, 'value'))
+
+    with nt.assert_raises(TypeError):
+        link((w1, 'value'), (w2, 'nosuchtrait'))
+
+    with nt.assert_raises(TypeError):
+        link((w1, 'value'), (w2, 'traits'))
+
+def test_dlink_args():
+    with nt.assert_raises(TypeError):
+        dlink()
+    w1 = ToggleButton()
+    with nt.assert_raises(TypeError):
+        dlink((w1, 'value'))
+    
+    w2 = ToggleButton()
+    dlink((w1, 'value'), (w2, 'value'))
+
+    with nt.assert_raises(TypeError):
+        dlink((w1, 'value'), (w2, 'nosuchtrait'))
+
+    with nt.assert_raises(TypeError):
+        dlink((w1, 'value'), (w2, 'traits'))