Add a -r --random option.

When passing -r or --random to the lettuce executable, we run both
features, and scenarios within features in a pseudo-random order.

This is helpful to detect issues that may arise from tests that
cause significant side-effects, the detection of locks etc

lettuce/__init__.py

@@ -23,6 +23,7 @@ import sys
 import traceback
 from imp import reload
 from datetime import datetime
+import random
 
 from lettuce.core import Feature, TotalResult
 
@@ -76,7 +77,7 @@ class Runner(object):
     Takes a base path as parameter (string), so that it can look for
     features and step definitions on there.
     """
-    def __init__(self, base_path, scenarios=None, verbosity=0,
+    def __init__(self, base_path, scenarios=None, verbosity=0, random=False,
                  enable_xunit=False, xunit_filename=None, tags=None):
         """ lettuce.Runner will try to find a terrain.py file and
         import it from within `base_path`
@@ -107,6 +108,8 @@ class Runner(object):
         else:
             from lettuce.plugins import colored_shell_output as output
 
+        self.random = random
+
         if enable_xunit:
             xunit_output.enable(filename=xunit_filename)
 
@@ -132,6 +135,8 @@ class Runner(object):
             features_files = [self.single_feature]
         else:
             features_files = self.loader.find_feature_files()
+            if self.random:
+                random.shuffle(features_files)
 
         if not features_files:
             self.output.print_no_features_found(self.loader.base_dir)
@@ -142,7 +147,7 @@ class Runner(object):
             for filename in features_files:
                 feature = Feature.from_file(filename)
                 results.append(
-                    feature.run(self.scenarios, tags=self.tags))
+                    feature.run(self.scenarios, tags=self.tags, random=self.random))
 
         except exceptions.LettuceSyntaxError, e:
             sys.stderr.write(e.msg)

lettuce/bin.py

@@ -47,6 +47,12 @@ def main(args=sys.argv[1:]):
                       '(prefixing tags with "-" will exclude them and '
                       'prefixing with "~" will match approximate words)')
 
+    parser.add_option("-r", "--random",
+                      dest="random",
+                      action="store_true",
+                      default=False,
+                      help="Run scenarios in a more random order to avoid interference")
+
     parser.add_option("--with-xunit",
                       dest="enable_xunit",
                       action="store_true",
@@ -73,6 +79,7 @@ def main(args=sys.argv[1:]):
         base_path,
         scenarios=options.scenarios,
         verbosity=options.verbosity,
+        random=options.random,
         enable_xunit=options.enable_xunit,
         xunit_filename=options.xunit_file,
         tags=options.tags,

lettuce/core.py

@@ -15,6 +15,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+import random as rand
 import re
 import codecs
 from fuzzywuzzy import fuzz
@@ -983,10 +984,13 @@ class Feature(object):
 
         return scenarios, description
 
-    def run(self, scenarios=None, ignore_case=True, tags=None):
+    def run(self, scenarios=None, ignore_case=True, tags=None, random=False):
         call_hook('before_each', 'feature', self)
         scenarios_ran = []
 
+        if random:
+            rand.shuffle(self.scenarios)
+
         if isinstance(scenarios, (tuple, list)):
             if all(map(lambda x: isinstance(x, int), scenarios)):
                 scenarios_to_run = scenarios

tests/functional/test_runner.py

@@ -15,8 +15,9 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 import os
+import random
 import lettuce
-from mock import Mock
+from mock import Mock, patch
 from StringIO import StringIO
 from os.path import dirname, join, abspath
 from nose.tools import assert_equals, with_setup, assert_raises
@@ -1096,3 +1097,12 @@ def test_run_only_fast_tests():
         "1 scenario (1 passed)\n"
         "2 steps (2 passed)\n"
     )
+
+def test_run_random():
+    "Randomise the feature order"
+    filename = tag_feature_name('timebound')
+    runner = Runner('some_basepath', random=True)
+    assert_equals(True, runner.random)
+    with patch.object(random, 'shuffle') as pshuffle:
+        runner.run()
+        pshuffle.assert_called_once_with([])