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Testing Django South Migration Merge Command Handling in thefuck

This test suite validates Django South migration merge functionality in the thefuck project, focusing on handling inconsistent migration histories and command corrections. The tests ensure proper handling of migration conflicts and the automatic addition of the –merge flag.

Test Coverage Overview

The test suite provides comprehensive coverage of Django South migration merge scenarios.

Key areas tested include:

Migration sequence validation
Inconsistent migration history detection
Command pattern matching for migration commands
Automatic merge flag addition

Implementation Analysis

The testing approach uses pytest fixtures to simulate Django South migration errors and validate command corrections. The implementation follows a pattern of testing both positive and negative matches for migration commands, ensuring robust command pattern recognition and transformation.

Technical Details

Testing components include:

pytest framework for test organization
Command object mocking
Fixture-based test data
Migration error simulation
Pattern matching validation

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Comprehensive fixture usage for consistent test data
Clear separation of match and command generation tests
Multiple assertion cases covering both valid and invalid scenarios
Explicit error message validation

nvbn/thefuck

tests/rules/test_django_south_merge.py

            
import pytest
from thefuck.rules.django_south_merge import match, get_new_command
from thefuck.types import Command


@pytest.fixture
def output():
    return '''Running migrations for app:
 ! Migration app:0003_auto... should not have been applied before app:0002_auto__add_field_query_due_date_ but was.
Traceback (most recent call last):
  File "/home/nvbn/work/.../bin/python", line 42, in <module>
    exec(compile(__file__f.read(), __file__, "exec"))
  File "/home/nvbn/work/.../app/manage.py", line 34, in <module>
    execute_from_command_line(sys.argv)
  File "/home/nvbn/work/.../lib/django/core/management/__init__.py", line 443, in execute_from_command_line
    utility.execute()
  File "/home/nvbn/work/.../lib/django/core/management/__init__.py", line 382, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/nvbn/work/.../lib/django/core/management/base.py", line 196, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/home/nvbn/work/.../lib/django/core/management/base.py", line 232, in execute
    output = self.handle(*args, **options)
  File "/home/nvbn/work/.../app/lib/south/management/commands/migrate.py", line 108, in handle
    ignore_ghosts = ignore_ghosts,
  File "/home/nvbn/work/.../app/lib/south/migration/__init__.py", line 207, in migrate_app
    raise exceptions.InconsistentMigrationHistory(problems)
south.exceptions.InconsistentMigrationHistory: Inconsistent migration history
The following options are available:
    --merge: will just attempt the migration ignoring any potential dependency conflicts.
'''


def test_match(output):
    assert match(Command('./manage.py migrate', output))
    assert match(Command('python manage.py migrate', output))
    assert not match(Command('./manage.py migrate', ''))
    assert not match(Command('app migrate', output))
    assert not match(Command('./manage.py test', output))


def test_get_new_command():
    assert (get_new_command(Command('./manage.py migrate auth', ''))
            == './manage.py migrate auth --merge')