Issue #9554: Use modern unittest features in test_argparse.

Initial patch by Denver Coneybeare and Radu Voicilas.

Lib/test/test_argparse.py

@@ -20,15 +20,6 @@ class StdIOBuffer(StringIO):
 
 class TestCase(unittest.TestCase):
 
-    def assertEqual(self, obj1, obj2):
-        if obj1 != obj2:
-            print('')
-            print(repr(obj1))
-            print(repr(obj2))
-            print(obj1)
-            print(obj2)
-        super(TestCase, self).assertEqual(obj1, obj2)
-
     def setUp(self):
         # The tests assume that line wrapping occurs at 80 columns, but this
         # behaviour can be overridden by setting the COLUMNS environment
@@ -1993,14 +1984,9 @@ class TestAddSubparsers(TestCase):
             '''))
 
     def _test_subparser_help(self, args_str, expected_help):
-        try:
+        with self.assertRaises(ArgumentParserError) as cm:
             self.parser.parse_args(args_str.split())
-        except ArgumentParserError:
-            err = sys.exc_info()[1]
-            if err.stdout != expected_help:
-                print(repr(expected_help))
-                print(repr(err.stdout))
-            self.assertEqual(err.stdout, expected_help)
+        self.assertEqual(expected_help, cm.exception.stdout)
 
     def test_subparser1_help(self):
         self._test_subparser_help('5.0 1 -h', textwrap.dedent('''\
@@ -2839,15 +2825,15 @@ class TestGetDefault(TestCase):
 
     def test_get_default(self):
         parser = ErrorRaisingArgumentParser()
-        self.assertEqual(None, parser.get_default("foo"))
-        self.assertEqual(None, parser.get_default("bar"))
+        self.assertIsNone(parser.get_default("foo"))
+        self.assertIsNone(parser.get_default("bar"))
 
         parser.add_argument("--foo")
-        self.assertEqual(None, parser.get_default("foo"))
-        self.assertEqual(None, parser.get_default("bar"))
+        self.assertIsNone(parser.get_default("foo"))
+        self.assertIsNone(parser.get_default("bar"))
 
         parser.add_argument("--bar", type=int, default=42)
-        self.assertEqual(None, parser.get_default("foo"))
+        self.assertIsNone(parser.get_default("foo"))
         self.assertEqual(42, parser.get_default("bar"))
 
         parser.set_defaults(foo="badger")
@@ -2862,18 +2848,16 @@ class TestNamespaceContainsSimple(TestCase):
 
     def test_empty(self):
         ns = argparse.Namespace()
-        self.assertEqual('' in ns, False)
-        self.assertEqual('' not in ns, True)
-        self.assertEqual('x' in ns, False)
+        self.assertNotIn('', ns)
+        self.assertNotIn('x', ns)
 
     def test_non_empty(self):
         ns = argparse.Namespace(x=1, y=2)
-        self.assertEqual('x' in ns, True)
-        self.assertEqual('x' not in ns, False)
-        self.assertEqual('y' in ns, True)
-        self.assertEqual('' in ns, False)
-        self.assertEqual('xx' in ns, False)
-        self.assertEqual('z' in ns, False)
+        self.assertNotIn('', ns)
+        self.assertIn('x', ns)
+        self.assertIn('y', ns)
+        self.assertNotIn('xx', ns)
+        self.assertNotIn('z', ns)
 
 # =====================
 # Help formatting tests
@@ -2929,13 +2913,6 @@ class TestHelpFormattingMetaclass(type):
             def _test(self, tester, parser_text):
                 expected_text = getattr(tester, self.func_suffix)
                 expected_text = textwrap.dedent(expected_text)
-                if expected_text != parser_text:
-                    print(repr(expected_text))
-                    print(repr(parser_text))
-                    for char1, char2 in zip(expected_text, parser_text):
-                        if char1 != char2:
-                            print('first diff: %r %r' % (char1, char2))
-                            break
                 tester.assertEqual(expected_text, parser_text)
 
             def test_format(self, tester):
@@ -4216,24 +4193,17 @@ class TestInvalidArgumentConstructors(TestCase):
         self.assertValueError('foo', action='baz')
         self.assertValueError('--foo', action=('store', 'append'))
         parser = argparse.ArgumentParser()
-        try:
+        with self.assertRaises(ValueError) as cm:
             parser.add_argument("--foo", action="store-true")
-        except ValueError:
-            e = sys.exc_info()[1]
-            expected = 'unknown action'
-            msg = 'expected %r, found %r' % (expected, e)
-            self.assertTrue(expected in str(e), msg)
+        self.assertIn('unknown action', str(cm.exception))
 
     def test_multiple_dest(self):
         parser = argparse.ArgumentParser()
         parser.add_argument(dest='foo')
-        try:
+        with self.assertRaises(ValueError) as cm:
             parser.add_argument('bar', dest='baz')
-        except ValueError:
-            e = sys.exc_info()[1]
-            expected = 'dest supplied twice for positional argument'
-            msg = 'expected %r, found %r' % (expected, e)
-            self.assertTrue(expected in str(e), msg)
+        self.assertIn('dest supplied twice for positional argument',
+                      str(cm.exception))
 
     def test_no_argument_actions(self):
         for action in ['store_const', 'store_true', 'store_false',
@@ -4390,18 +4360,10 @@ class TestConflictHandling(TestCase):
 class TestOptionalsHelpVersionActions(TestCase):
     """Test the help and version actions"""
 
-    def _get_error(self, func, *args, **kwargs):
-        try:
-            func(*args, **kwargs)
-        except ArgumentParserError:
-            return sys.exc_info()[1]
-        else:
-            self.assertRaises(ArgumentParserError, func, *args, **kwargs)
-
     def assertPrintHelpExit(self, parser, args_str):
-        self.assertEqual(
-            parser.format_help(),
-            self._get_error(parser.parse_args, args_str.split()).stdout)
+        with self.assertRaises(ArgumentParserError) as cm:
+            parser.parse_args(args_str.split())
+        self.assertEqual(parser.format_help(), cm.exception.stdout)
 
     def assertArgumentParserError(self, parser, *args):
         self.assertRaises(ArgumentParserError, parser.parse_args, args)
@@ -4416,8 +4378,9 @@ class TestOptionalsHelpVersionActions(TestCase):
     def test_version_format(self):
         parser = ErrorRaisingArgumentParser(prog='PPP')
         parser.add_argument('-v', '--version', action='version', version='%(prog)s 3.5')
-        msg = self._get_error(parser.parse_args, ['-v']).stdout
-        self.assertEqual('PPP 3.5\n', msg)
+        with self.assertRaises(ArgumentParserError) as cm:
+            parser.parse_args(['-v'])
+        self.assertEqual('PPP 3.5\n', cm.exception.stdout)
 
     def test_version_no_help(self):
         parser = ErrorRaisingArgumentParser(add_help=False)
@@ -4429,8 +4392,9 @@ class TestOptionalsHelpVersionActions(TestCase):
     def test_version_action(self):
         parser = ErrorRaisingArgumentParser(prog='XXX')
         parser.add_argument('-V', action='version', version='%(prog)s 3.7')
-        msg = self._get_error(parser.parse_args, ['-V']).stdout
-        self.assertEqual('XXX 3.7\n', msg)
+        with self.assertRaises(ArgumentParserError) as cm:
+            parser.parse_args(['-V'])
+        self.assertEqual('XXX 3.7\n', cm.exception.stdout)
 
     def test_no_help(self):
         parser = ErrorRaisingArgumentParser(add_help=False)
@@ -4600,14 +4564,10 @@ class TestArgumentTypeError(TestCase):
 
         parser = ErrorRaisingArgumentParser(prog='PROG', add_help=False)
         parser.add_argument('x', type=spam)
-        try:
+        with self.assertRaises(ArgumentParserError) as cm:
             parser.parse_args(['XXX'])
-        except ArgumentParserError:
-            expected = 'usage: PROG x\nPROG: error: argument x: spam!\n'
-            msg = sys.exc_info()[1].stderr
-            self.assertEqual(expected, msg)
-        else:
-            self.fail()
+        self.assertEqual('usage: PROG x\nPROG: error: argument x: spam!\n',
+                         cm.exception.stderr)
 
 # =========================
 # MessageContentError tests

Misc/ACKS

@@ -1399,6 +1399,7 @@ Norman Vine
 Pauli Virtanen
 Frank Visser
 Johannes Vogel
+Radu Voicilas
 Alex Volkov
 Martijn Vries
 Sjoerd de Vries

Misc/NEWS

@@ -653,6 +653,9 @@ Documentation
 Tests
 -----
 
+- Issue #9554: Use modern unittest features in test_argparse. Initial patch by
+  Denver Coneybeare and Radu Voicilas.
+
 - Issue #20155: Changed HTTP method names in failing tests in test_httpservers
   so that packet filtering software (specifically Windows Base Filtering Engine)
   does not interfere with the transaction semantics expected by the tests.