'`showmigrations --plan app_label` output with a single app_label.'

@override_settings(INSTALLED_APPS=['migrations.migrations_test_apps.mutate_state_b', 'migrations.migrations_test_apps.alter_fk.author_app', 'migrations.migrations_test_apps.alter_fk.book_app'])
def test_showmigrations_plan_single_app_label(self):

    out = io.StringIO()
    call_command('showmigrations', 'mutate_state_b', format='plan', stdout=out)
    self.assertEqual('[    ]        mutate_state_b.0001_initial\n[    ]        mutate_state_b.0002_add_field\n', out.getvalue())
    out = io.StringIO()
    call_command('showmigrations', 'author_app', format='plan', stdout=out)
    self.assertEqual('[    ]        author_app.0001_initial\n[    ]        book_app.0001_initial\n[    ]        author_app.0002_alter_id\n', out.getvalue())
    call_command('migrate', 'author_app', '0001', verbosity=0)
    out = io.StringIO()
    call_command('showmigrations', 'author_app', format='plan', stdout=out)
    self.assertEqual('[X]        author_app.0001_initial\n[    ]        book_app.0001_initial\n[    ]        author_app.0002_alter_id\n', out.getvalue())
    call_command('migrate', 'author_app', 'zero', verbosity=0)
