case.{Function,Method}TestCase: deobfuscate references to self.arg_repr

Previously, both `FunctionTestCase` and `MethodTestCase` created local
`arg` variables in their `__str__` methods. These variables were simply
references to `self.arg_repr`, so this commit deobfuscates this reference
by modifying the `_descriptors` method for each so that *only the test
name* is returned and not the `arg_repr` also (renaming `_descriptors` to
`_descriptor` in the process), and then referring to `self.arg_repr`
directly.

This makes the `__str__` easier to understand because it is immediately
obvious that we're only dealing with the string-representation of the args
and *not* the actual args themselves.

nose/case.py

@@ -199,7 +199,7 @@ def runTest(self):
     def shortDescription(self):
         if hasattr(self.test, 'description'):
             return self.test.description
-        func, arg = self._descriptors()
+        func = self._descriptor()
         doc = getattr(func, '__doc__', None)
         if not doc:
             doc = str(self)
@@ -277,32 +277,27 @@ def tearDown(self):
             try_run(self.test, names)
 
     def __str__(self):
-        func, arg = self._descriptors()
+        func = self._descriptor()
         if hasattr(func, 'compat_func_name'):
             name = func.compat_func_name
         else:
             name = func.__name__
         name = "%s.%s" % (func.__module__, name)
-        if not arg == '()':
-            name = "%s%s" % (name, arg)
+        if not self.arg_repr == '()':
+            name = "%s%s" % (name, self.arg_repr)
         # FIXME need to include the full dir path to disambiguate
         # in cases where test module of the same name was seen in
         # another directory (old fromDirectory)
         return name
     __repr__ = __str__
 
-    def _descriptors(self):
-        """Get the descriptors of the test function: the function and
-        arguments that will be used to construct the test name. In
-        most cases, this is the function itself and no arguments. For
-        tests generated by generator functions, the original
-        (generator) function and args passed to the generated function
-        are returned.
+    def _descriptor(self):
+        """Get the descriptor of the test method.
+
+        If a `descriptor` was specified for __init__, then it is returned, else
+        the test method (callable object) is returned.
         """
-        if self.descriptor:
-            return self.descriptor, self.arg_repr
-        else:
-            return self.test, self.arg_repr
+        return self.descriptor if self.descriptor is not None else self.test
 
 
 class MethodTestCase(TestBase):
@@ -351,16 +346,16 @@ def __init__(self, method, test=None, arg=tuple(), descriptor=None):
         TestBase.__init__(self)
 
     def __str__(self):
-        func, arg = self._descriptors()
+        func = self._descriptor()
         if hasattr(func, 'compat_func_name'):
             name = func.compat_func_name
         else:
             name = func.__name__
         name = "%s.%s.%s" % (self.cls.__module__,
                              self.cls.__name__,
                              name)
-        if not arg == '()':
-            name = "%s%s" % (name, arg)
+        if not self.arg_repr == '()':
+            name = "%s%s" % (name, self.arg_repr)
         return name
     __repr__ = __str__
 
@@ -385,15 +380,10 @@ def setUp(self):
     def tearDown(self):
         try_run(self.inst, ('teardown', 'tearDown'))
 
-    def _descriptors(self):
-        """Get the descriptors of the test method: the method and
-        arguments that will be used to construct the test name. In
-        most cases, this is the method itself and no arguments. For
-        tests generated by generator methods, the original
-        (generator) method and args passed to the generated method 
-        or function are returned.
+    def _descriptor(self):
+        """Get the descriptor of the test method.
+
+        If a `descriptor` was specified for __init__, then it is returned, else
+        the test method (callable object) is returned.
         """
-        if self.descriptor:
-            return self.descriptor, self.arg_repr
-        else:
-            return self.method, self.arg_repr
+        return self.descriptor if self.descriptor is not None else self.method