Use 'is' in place of '==' for determining whether Python object has c…

…hanged in Fire.

Copybara generated commit for Python Fire.

PiperOrigin-RevId: 149692390
Change-Id: I6fb5413ba2c9d5eed654d6710f8cc756180e90dc
Reviewed-on: https://team-review.git.corp.google.com/63904
Reviewed-by: David Bieber <[email protected]>

fire/core.py

@@ -339,7 +339,7 @@ def _Fire(component, args, context, name=None):
         component_trace.AddError(error, initial_args)
         return component_trace
 
-      if last_component == initial_component:
+      if last_component is initial_component:
         # If the initial component is a class, keep an instance for use with -i.
         instance = component
 
@@ -419,13 +419,13 @@ def _Fire(component, args, context, name=None):
             or inspect.isroutine(last_component)):
         remaining_args = saved_args
         component_trace.AddSeparator()
-      elif component != last_component:
+      elif component is not last_component:
         remaining_args = [separator] + saved_args
       else:
         # It was an unnecessary separator.
         remaining_args = saved_args
 
-    if component == last_component and remaining_args == initial_args:
+    if component is last_component and remaining_args == initial_args:
       # We're making no progress.
       break
 

fire/fire_test.py

@@ -317,6 +317,14 @@ def testBasicSeparator(self):
     # The separator triggers a function call, but there aren't enough arguments.
     self.assertEqual(fire.Fire(tc.MixedDefaults, 'identity - _ +'), None)
 
+  def testNonComparable(self):
+    """Fire should work with classes that disallow comparisons."""
+    self.assertIsInstance(fire.Fire(tc.NonComparable, ''), tc.NonComparable)
+
+    # The first separator instantiates the NonComparable object.
+    # The second separator causes Fire to check if the separator was necessary.
+    self.assertIsInstance(fire.Fire(tc.NonComparable, '- -'), tc.NonComparable)
+
   def testExtraSeparators(self):
     self.assertEqual(
         fire.Fire(tc.ReturnsObj, 'get-obj arg1 arg2 - - as-bool True'), True)

fire/test_components.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-"""Thie module has componenets that are used for testing Python Fire."""
+"""Thie module has components that are used for testing Python Fire."""
 
 from __future__ import absolute_import
 from __future__ import division
@@ -180,3 +180,12 @@ class ErrorRaiser(object):
 
   def fail(self):
     raise ValueError('This error is part of a test.')
+
+
+class NonComparable(object):
+
+  def __eq__(self, other):
+    raise ValueError('Instances of this class cannot be compared.')
+
+  def __ne__(self, other):
+    raise ValueError('Instances of this class cannot be compared.')

fire/test_components_test.py

@@ -28,6 +28,12 @@ def testTestComponents(self):
     self.assertIsNotNone(tc.Empty)
     self.assertIsNotNone(tc.OldStyleEmpty)
 
+  def testNonComparable(self):
+    with self.assertRaises(ValueError):
+      tc.NonComparable() != 2  # pylint: disable=expression-not-assigned
+    with self.assertRaises(ValueError):
+      tc.NonComparable() == 2  # pylint: disable=expression-not-assigned
+
 
 if __name__ == '__main__':
   unittest.main()