Merge branch 'error-when-duplicate-entry-points' into 'master'

Emit an error when entry points are duplicated

Closes #634

See merge request pycqa/flake8!425

tests/fixtures/config_files/local-plugin-duplicate-entry-point.ini

@@ -0,0 +1,4 @@
+[flake8:local-plugins]
+extension =
+  XE = aplugin:ExtensionTestPluginA
+  XE = aplugin:ExtensionTestPluginB

tests/integration/test_plugins.py

@@ -1,9 +1,13 @@
 """Integration tests for plugin loading."""
+import pytest
+
 from flake8.main import application
+from flake8 import exceptions
 
 
 LOCAL_PLUGIN_CONFIG = 'tests/fixtures/config_files/local-plugin.ini'
 LOCAL_PLUGIN_PATH_CONFIG = 'tests/fixtures/config_files/local-plugin-path.ini'
+LOCAL_PLUGIN_DUPLICATE_CONFIG = 'tests/fixtures/config_files/local-plugin-duplicate-entry-point.ini'
 
 
 class ExtensionTestPlugin(object):
@@ -61,3 +65,10 @@ def test_enable_local_plugin_at_non_installed_path():
     app.initialize(['flake8', '--config', LOCAL_PLUGIN_PATH_CONFIG])
 
     assert app.check_plugins['XE'].plugin.name == 'ExtensionTestPlugin2'
+
+
+def test_reject_local_plugins_with_duplicate_entry_point():
+    """Reject duplicate entry points in local-plugins config section."""
+    with pytest.raises(exceptions.DuplicatePluginEntryPoint):
+        app = application.Application()
+        app.initialize(['flake8', '--config', LOCAL_PLUGIN_DUPLICATE_CONFIG])

tests/unit/test_application.py

@@ -48,6 +48,18 @@ def test_exit_does_raise(result_count, catastrophic, exit_zero, value,
     assert excinfo.value.args[0] is value
 
 
+def test_exit_raises(application):
+    """Verify Application.exit raises SystemExit under configuration failure."""
+    application.catastrophic_failure = True
+    # Note: no application.options set -- configuration issues can lead to
+    # errors before it's assigned.
+
+    with pytest.raises(SystemExit) as excinfo:
+        application.exit()
+
+    assert excinfo.value.args[0] is True
+
+
 def test_warns_on_unknown_formatter_plugin_name(application):
     """Verify we log a warning with an unfound plugin."""
     default = mock.Mock()