Test "unable" exception, add help

peewee_migrate/cli.py

@@ -86,14 +86,21 @@ def create(name, database=None, auto=False, auto_source=False, directory=None, v
 
 @cli.command()
 @click.argument('name', required=False)
-@click.option('--count', required=False, default=1, type=int)
+@click.option('--count',
+              required=False, 
+              default=1, 
+              type=int, 
+              help="Number of last migrations to be rolled back."
+                   "Ignored in case of non-empty name")
 @click.option('--database', default=None, help="Database connection")
-@click.option('--directory', default='migrations', help="Directory where migrations are stored")
+@click.option('--directory', 
+              default='migrations', 
+              help="Directory where migrations are stored")
 @click.option('-v', '--verbose', count=True)
 def rollback(name, count, database=None, directory=None, verbose=None):
     """
-    Rollback a migration with given name or number of migrations with given
-    name as integer number
+    Rollback a migration with given name or number of last migrations 
+    with given --count option as integer number
     """
     router = get_router(directory, database, verbose)
     if not name:

tests/test_cli.py

@@ -1,8 +1,7 @@
 from click.testing import CliRunner
 import pytest
 
-from peewee_migrate.cli import cli
-from peewee_migrate.cli import get_router
+from peewee_migrate.cli import cli, get_router
 
 runner = CliRunner()
 
@@ -72,6 +71,12 @@ def test_list(dir_option, db_option, migrations):
 def test_rollback(dir_option, db_option, router, migrations):
     router().run()
 
+    count_overflow = len(migrations) + 1
+    result = runner.invoke(cli, ['rollback', dir_option, db_option, '--count=%s' % count_overflow])
+    assert result.exception
+    assert 'Unable to rollback %s migrations' % count_overflow in result.exception.args[0]
+    assert router().done == migrations
+
     result = runner.invoke(cli, ['rollback', dir_option, db_option])
     assert not result.exception
     assert router().done == migrations[:-1]
@@ -87,6 +92,7 @@ def test_rollback(dir_option, db_option, router, migrations):
     result = runner.invoke(cli, ['rollback', dir_option, db_option, '005_test'])
     assert result.exception
     assert result.exception.args[0] == 'Only last migration can be canceled.'
+    assert router().done == migrations[:-4]
 
 
 def test_fake(dir_option, db_option, migrations_str, router):