Add load_tests_apply_scenarios

3 files changed, 60 insertions, 0 deletions

diff --git a/README b/README
index b827cb6..14df2e1 100644
--- a/README
+++ b/README
@@ -128,6 +128,19 @@ With ``load_tests``::
   ...     result.addTests(generate_scenarios(standard_tests))
   ...     return result
 
+as a convenience, this is available in ``load_tests_apply_scenarios``, so a
+module using scenario tests need only say ::
+
+    from testscenarios import load_tests_apply_scenarios
+
+    load_tests = load_tests_apply_scenarios
+
+It's suggested for clarity this be done near the top of the file.
+
+Python 2.7 and greater support a different calling convention for `load_tests``
+<https://bugs.launchpad.net/bzr/+bug/607412>.  `load_tests_apply_scenarios`
+copes with both.
+
 With ``test_suite``::
 
   >>> def test_suite():
diff --git a/lib/testscenarios/scenarios.py b/lib/testscenarios/scenarios.py
index e531b2e..f008d50 100644
--- a/lib/testscenarios/scenarios.py
+++ b/lib/testscenarios/scenarios.py
@@ -2,6 +2,7 @@
 #  dependency injection ('scenarios') by tests.
 #
 # Copyright (c) 2009, Robert Collins <robertc@robertcollins.net>
+# Copyright (c) 2010 Martin Pool <mbp@sourcefrog.net>
 # 
 # Licensed under either the Apache License, Version 2.0 or the BSD 3-clause
 # license at the users choice. A copy of both licenses are available in the
@@ -18,6 +19,7 @@ __all__ = [
     'apply_scenario',
     'apply_scenarios',
     'generate_scenarios',
+    'load_tests_apply_scenarios',
     ]
 
 import unittest
@@ -76,3 +78,25 @@ def generate_scenarios(test_or_suite):
                 yield newtest
         else:
             yield test
+
+
+def load_tests_apply_scenarios(loader, standard_tests, pattern):
+    """Multiply out all tests in a module that have scenarios.
+
+    If this is referenced by the `load_tests` attribute of a module, then
+    Python2.7 or other testloaders that implement this protocol will
+    automatically arrange for the scenarios to be expanded.  In this case it
+    is not necessary (or desirable) to subclass TestWithScenarios.
+
+    Note that this function implements the protocol used by Python2.7 
+    <http://docs.python.org/library/unittest.html#load-tests-protocol> which
+    is different from the `load_tests` method originally used in bzr 
+    and some other projects <http://pad.lv/607412>.
+
+    :param loader: A TestLoader.
+    :param standard_test: The test objects found in this module before 
+        multiplication.
+    """
+    result = loader.suiteClass()
+    result.addTests(generate_scenarios(standard_tests))
+    return result
diff --git a/lib/testscenarios/tests/test_scenarios.py b/lib/testscenarios/tests/test_scenarios.py
index 4c80150..621cfdc 100644
--- a/lib/testscenarios/tests/test_scenarios.py
+++ b/lib/testscenarios/tests/test_scenarios.py
@@ -2,6 +2,7 @@
 #  dependency injection ('scenarios') by tests.
 #
 # Copyright (c) 2009, Robert Collins <robertc@robertcollins.net>
+# Copyright (c) 2010 Martin Pool <mbp@sourcefrog.net>
 # 
 # Licensed under either the Apache License, Version 2.0 or the BSD 3-clause
 # license at the users choice. A copy of both licenses are available in the
@@ -21,6 +22,7 @@ from testscenarios.scenarios import (
     apply_scenario,
     apply_scenarios,
     generate_scenarios,
+    load_tests_apply_scenarios,
     )
 import testtools
 from testtools.tests.helpers import LoggingResult
@@ -171,3 +173,24 @@ class TestApplyScenarios(testtools.TestCase):
         tests = list(apply_scenarios(ReferenceTest.scenarios, test))
         self.assertEqual([('demo', {})], ReferenceTest.scenarios)
         self.assertEqual(ReferenceTest.scenarios, tests[0].scenarios)
+
+
+class TestLoadTests(testtools.TestCase):
+
+    def test_load_tests_apply_scenarios(self):
+        class SampleTest(unittest.TestCase):
+            def test_nothing(self): 
+                pass
+            scenarios = [
+                ('a', {}),
+                ('b', {}),
+                ]
+        suite = load_tests_apply_scenarios(
+            unittest.TestLoader(),
+            [SampleTest('test_nothing')],
+            None)
+        result_tests = list(testtools.iterate_tests(suite))
+        self.assertEquals(
+            2,
+            len(result_tests),
+            result_tests)