1 files changed, 81 insertions, 0 deletions
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index 2e6584f..c06c940 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -1463,6 +1463,22 @@ class TestFileTypeR(TempDirMixin, ParserTestCase):
         ('readonly', NS(x=None, spam=RFile('readonly'))),
     ]
 
+class TestFileTypeDefaults(TempDirMixin, ParserTestCase):
+    """Test that a file is not created unless the default is needed"""
+    def setUp(self):
+        super(TestFileTypeDefaults, self).setUp()
+        file = open(os.path.join(self.temp_dir, 'good'), 'w')
+        file.write('good')
+        file.close()
+
+    argument_signatures = [
+        Sig('-c', type=argparse.FileType('r'), default='no-file.txt'),
+    ]
+    # should provoke no such file error
+    failures = ['']
+    # should not provoke error because default file is created
+    successes = [('-c good', NS(c=RFile('good')))]
+
 
 class TestFileTypeRB(TempDirMixin, ParserTestCase):
     """Test the FileType option/argument type for reading files"""
@@ -4559,6 +4575,71 @@ class TestMessageContentError(TestCase):
         self.assertNotIn(msg, 'optional_positional')
 
 
+# ================================================
+# Check that the type function is called only once
+# ================================================
+
+class TestTypeFunctionCallOnlyOnce(TestCase):
+
+    def test_type_function_call_only_once(self):
+        def spam(string_to_convert):
+            self.assertEqual(string_to_convert, 'spam!')
+            return 'foo_converted'
+
+        parser = argparse.ArgumentParser()
+        parser.add_argument('--foo', type=spam, default='bar')
+        args = parser.parse_args('--foo spam!'.split())
+        self.assertEqual(NS(foo='foo_converted'), args)
+
+# ==================================================================
+# Check semantics regarding the default argument and type conversion
+# ==================================================================
+
+class TestTypeFunctionCalledOnDefault(TestCase):
+
+    def test_type_function_call_with_non_string_default(self):
+        def spam(int_to_convert):
+            self.assertEqual(int_to_convert, 0)
+            return 'foo_converted'
+
+        parser = argparse.ArgumentParser()
+        parser.add_argument('--foo', type=spam, default=0)
+        args = parser.parse_args([])
+        # foo should *not* be converted because its default is not a string.
+        self.assertEqual(NS(foo=0), args)
+
+    def test_type_function_call_with_string_default(self):
+        def spam(int_to_convert):
+            return 'foo_converted'
+
+        parser = argparse.ArgumentParser()
+        parser.add_argument('--foo', type=spam, default='0')
+        args = parser.parse_args([])
+        # foo is converted because its default is a string.
+        self.assertEqual(NS(foo='foo_converted'), args)
+
+    def test_no_double_type_conversion_of_default(self):
+        def extend(str_to_convert):
+            return str_to_convert + '*'
+
+        parser = argparse.ArgumentParser()
+        parser.add_argument('--test', type=extend, default='*')
+        args = parser.parse_args([])
+        # The test argument will be two stars, one coming from the default
+        # value and one coming from the type conversion being called exactly
+        # once.
+        self.assertEqual(NS(test='**'), args)
+
+    def test_issue_15906(self):
+        # Issue #15906: When action='append', type=str, default=[] are
+        # providing, the dest value was the string representation "[]" when it
+        # should have been an empty list.
+        parser = argparse.ArgumentParser()
+        parser.add_argument('--test', dest='test', type=str,
+                            default=[], action='append')
+        args = parser.parse_args([])
+        self.assertEqual(args.test, [])
+
 # ======================
 # parse_known_args tests
 # ======================