Add basic tests for CommandChainDispatcher

IPython/core/tests/test_hooks.py

@@ -0,0 +1,75 b''
+# -*- coding: utf-8 -*-
+"""Tests for CommandChainDispatcher."""
+
+from __future__ import absolute_import
+
+#-----------------------------------------------------------------------------
+# Imports
+#-----------------------------------------------------------------------------
+
+import nose.tools as nt
+from IPython.core.error import TryNext
+from IPython.core.hooks import CommandChainDispatcher
+
+#-----------------------------------------------------------------------------
+# Local utilities
+#-----------------------------------------------------------------------------
+
+# Define two classes, one which succeeds and one which raises TryNext. Each
+# sets the attribute `called` to True when it is called.
+class Okay(object):
+    def __init__(self, message):
+        self.message = message
+        self.called = False
+    def __call__(self):
+        self.called = True
+        return self.message
+
+class Fail(object):
+    def __init__(self, message):
+        self.message = message
+        self.called = False
+    def __call__(self):
+        self.called = True
+        raise TryNext(self.message)
+
+#-----------------------------------------------------------------------------
+# Test functions
+#-----------------------------------------------------------------------------
+
+def test_command_chain_dispatcher_ff():
+    """Test two failing hooks"""
+    fail1 = Fail(u'fail1')
+    fail2 = Fail(u'fail2')
+    dp = CommandChainDispatcher([(0, fail1),
+                                 (10, fail2)])
+
+    try:
+        dp()
+    except TryNext as e:
+        nt.assert_equal(str(e), u'fail2')
+    else:
+        assert False, "Expected exception was not raised."
+
+    nt.assert_true(fail1.called)
+    nt.assert_true(fail2.called)
+
+def test_command_chain_dispatcher_fofo():
+    """Test a mixture of failing and succeeding hooks."""
+    fail1 = Fail(u'fail1')
+    fail2 = Fail(u'fail2')
+    okay1 = Okay(u'okay1')
+    okay2 = Okay(u'okay2')
+
+    dp = CommandChainDispatcher([(0, fail1),
+                                 # (5, okay1), # add this later
+                                 (10, fail2),
+                                 (15, okay2)])
+    dp.add(okay1, 5)
+
+    nt.assert_equal(dp(), u'okay1')
+
+    nt.assert_true(fail1.called)
+    nt.assert_true(okay1.called)
+    nt.assert_false(fail2.called)
+    nt.assert_false(okay2.called)