Change the --no-cache-dir error to use raise_option_error().

src/pip/_internal/cli/cmdoptions.py

@@ -555,7 +555,10 @@ def no_cache_dir_callback(option, opt, value, parser):
     # environment variable, like PIP_NO_CACHE_DIR=true.
     if value is not None:
         # Then parse the string value to get argument error-checking.
-        strtobool(value)
+        try:
+            strtobool(value)
+        except ValueError as exc:
+            raise_option_error(parser, option=option, msg=str(exc))
 
     # Originally, setting PIP_NO_CACHE_DIR to a value that strtobool()
     # converted to 0 (like "false" or "no") caused cache_dir to be disabled

tests/unit/test_options.py

@@ -26,17 +26,6 @@ def temp_environment_variable(name, value):
             os.environ[name] = original
 
 
-@contextmanager
-def assert_raises_message(exc_class, expected):
-    """
-    Assert that an exception with the given type and message is raised.
-    """
-    with pytest.raises(exc_class) as excinfo:
-        yield
-
-    assert str(excinfo.value) == expected
-
-
 @contextmanager
 def assert_option_error(capsys, expected):
     """
@@ -181,13 +170,16 @@ def test_cache_dir__PIP_NO_CACHE_DIR__with_no_cache_dir(
         # value in this case).
         assert options.cache_dir is False
 
-    def test_cache_dir__PIP_NO_CACHE_DIR_invalid__with_no_cache_dir(self):
+    def test_cache_dir__PIP_NO_CACHE_DIR_invalid__with_no_cache_dir(
+            self, capsys,
+    ):
         """
         Test setting PIP_NO_CACHE_DIR to an invalid value while also passing
         --no-cache-dir.
         """
         os.environ['PIP_NO_CACHE_DIR'] = 'maybe'
-        with assert_raises_message(ValueError, "invalid truth value 'maybe'"):
+        expected_err = "--no-cache-dir error: invalid truth value 'maybe'"
+        with assert_option_error(capsys, expected=expected_err):
             main(['--no-cache-dir', 'fake'])