Raise click.BadParameter if config contains unknown keys

click_config_file.py

@@ -90,6 +90,19 @@ def configuration_callback(cmd_name, option_name, config_file_name,
         except Exception as e:
             raise click.BadOptionUsage(option_name,
                 "Error reading configuration file: {}".format(e), ctx)
+
+        valid_params = [
+            p.name for p in ctx.command.params if p.name != option_name
+        ]
+        specified_params = list(config.keys())
+        unknown_params = set(specified_params).difference(set(valid_params))
+
+        if unknown_params:
+            raise click.BadParameter(
+                f'Invalid configuration file, the following keys are not '
+                f'supported: {unknown_params}', ctx, param
+            )
+
         ctx.default_map.update(config)
 
     return saved_callback(ctx, param, value) if saved_callback else value

tests/test_configuration_option_explicit.py

@@ -31,13 +31,14 @@ def cli(config):
 
 def test_custom_default_value(runner, cfgfile):
     @click.command()
+    @click.option('--who')
     @configuration_option(implicit=False, default=str(cfgfile), expose_value=True)
-    def cli(config):
+    def cli(who, config):
         assert config == str(cfgfile)
         click.echo(config)
 
     result = runner.invoke(cli)
-    assert not result.exception
+    assert not result.exception, result.output
     assert result.output == ''.join((
         str(cfgfile.realpath()),
         '\n',
@@ -60,9 +61,10 @@ def cli(who):
 def test_config_value_no_replacement(runner, cfgfile):
     """Test that config does not replace variable of other name."""
     @click.command()
+    @click.option('--who')
     @click.option('--whom', default='World', envvar='CLICK_TEST_WHO')
     @configuration_option(implicit=False)
-    def cli(whom):
+    def cli(who, whom):
         assert whom == "World"
         click.echo("Hello {}".format(whom))
 
@@ -73,6 +75,7 @@ def cli(whom):
     assert not result.exception
     assert result.output == 'Hello World\n'
 
+
 def test_broken_config(runner, tmpdir):
     @click.command()
     @configuration_option(implicit=False)
@@ -92,6 +95,25 @@ def cli():
     assert result.exit_code != 0
 
 
+def test_config_unknown_parameters(runner, cfgfile):
+    """Test that the command fails if the configuration file contains unknown parameters."""
+    @click.command()
+    @configuration_option(implicit=False)
+    def cli():
+        pass
+
+    result = runner.invoke(cli, (
+        '--config',
+        str(cfgfile),
+    ))
+    assert re.search(
+        r"Invalid configuration file, the following keys are not supported: {'who'}",
+        result.output
+    ) is not None
+    assert result.exception
+    assert result.exit_code != 0
+
+
 
 def test_config_precedence_override_default(runner, cfgfile):
     @click.command()