Suggest the preferred names for deprecated methods (#6)

This introduces a new error (A503) that suggests the preferred names for
deprecated methods, such as assertEqual() instead of assertEquals().

Because our existing suggestions are always use the preferred names, we
only emit this new error if we don't have any other suggestions to make.

Author: jparise

CHANGELOG.rst

@@ -1,6 +1,12 @@
 Changes
 =======
 
+1.2.0 (2019-12-05)
+------------------
+
+* Suggest the preferred names for deprecated methods, such as
+  ``assertEqual()`` instead of ``assertEquals()``.
+
 1.1.0 (2019-06-26)
 ------------------
 

README.rst

@@ -69,6 +69,14 @@ the generic methods.
 +------------------------------------------+-----------------------------------+------+
 | ``assertEqual(a, False)``                | ``assertFalse(a)``                | A502 |
 +------------------------------------------+-----------------------------------+------+
+| ``assertEquals(a, b)``                   | ``assertEqual(a, b)``             | A503 |
++------------------------------------------+-----------------------------------+------+
+| ``assertNotEquals(a, b)``                | ``assertNotEqual(a, b)``          | A503 |
++------------------------------------------+-----------------------------------+------+
+| ``assertAlmostEquals(a, b, x)``          | ``assertAlmostEqual(a, b, x)``    | A503 |
++------------------------------------------+-----------------------------------+------+
+| ``assertNotAlmostEquals(a, b, x)``       | ``assertNotAlmostEqual(a, b, x)`` | A503 |
++------------------------------------------+-----------------------------------+------+
 
 Note that some suggestions are normalized forms of the original, such as when
 a double-negative is used (``assertFalse(a != b)`` → ``assertEqual(a, b)``).
@@ -91,7 +99,7 @@ that it has been loaded by inspecting the ``flake8 --version`` string.
 .. code-block:: sh
 
     $ flake8 --version
-    3.7.7 (assertive: 1.1.0, ...) CPython 2.7.16 on Darwin
+    3.7.9 (assertive: 1.2.0, ...) CPython 2.7.17 on Darwin
 
 
 Error Codes
@@ -102,6 +110,7 @@ This extension adds three new `error codes`__ (using the ``A50`` prefix):
 - ``A500``: prefer *{func}* for '*{op}*' comparisons
 - ``A501``: prefer *{func}* for '*{op}*' expressions
 - ``A502``: prefer *{func}* instead of comparing to *{obj}*
+- ``A503``: use *{func}* instead of the deprecated *{name}*
 
 .. __: http://flake8.pycqa.org/en/latest/user/error-codes.html
 

flake8_assertive.py

@@ -25,7 +25,7 @@
 import re
 
 __all__ = ['Checker']
-__version__ = '1.1.0'
+__version__ = '1.2.0'
 
 
 # Python 3.4 introduced `ast.NameConstant` for `None`, `True`, and `False`.
@@ -49,6 +49,21 @@ def is_assert_method_call(node):
             node.func.attr.startswith('assert'))
 
 
+def wrap_deprecated(func, name):
+    """Return a check function for a deprecated assert method call.
+
+    If the `assertive-deprecated` option has been enabled and the wrapped
+    check function doesn't yield any errors of its own, this function will
+    yield an A503 error that includes the new name of deprecated method.
+    """
+    def wrapper(self, node):
+        for error in func(self, node):
+            yield error
+        else:
+            yield self.error(node, 'A503', func=name, name=node.func.attr)
+    return wrapper
+
+
 class Checker(object):
     """Unittest assert method checker"""
 
@@ -60,6 +75,7 @@ class Checker(object):
     A500 = "prefer {func}() for '{op}' comparisons"
     A501 = "prefer {func}() for '{op}' expressions"
     A502 = "prefer {func}() instead of comparing to {obj}"
+    A503 = "use {func}() instead of the deprecated {name}()"
 
     def __init__(self, tree, filename):
         self.tree = tree
@@ -140,11 +156,6 @@ def check_assertnotalmostequal(self, node):
                              'built-in rounding of assertNotAlmostEqual',
                              op='round')
 
-    check_assertequals = check_assertequal
-    check_assertnotequals = check_assertnotequal
-    check_assertalmostequals = check_assertalmostequal
-    check_assertnotalmostequals = check_assertnotalmostequal
-
     def check_asserttrue(self, node):
         if (isinstance(node.args[0], ast.Compare) and
                 len(node.args[0].ops) == 1):
@@ -204,3 +215,19 @@ def check_assertfalse(self, node):
         elif is_function_call(node.args[0], 'isinstance'):
             yield self.error(
                 node, 'A501', 'assertNotIsInstance', op='isinstance()')
+
+    check_assertequals = wrap_deprecated(
+        check_assertequal,
+        'assertEqual')
+
+    check_assertnotequals = wrap_deprecated(
+        check_assertnotequal,
+        'assertNotEqual')
+
+    check_assertalmostequals = wrap_deprecated(
+        check_assertalmostequal,
+        'assertAlmostEqual')
+
+    check_assertnotalmostequals = wrap_deprecated(
+        check_assertnotalmostequal,
+        'assertNotAlmostEqual')

tests/test_checker.py

@@ -160,3 +160,7 @@ def test_pattern(self):
     def test_snakecase(self):
         Checker.snakecase = True
         self.check("self.assert_equal(True, a)", "A502", "assert_true()")
+
+    def test_deprecated(self):
+        self.check("self.assertEquals(True, a)", "A502", "assertTrue()")
+        self.check("self.assertEquals(a, b)", "A503", "assertEqual()")