* ``run`` now accepts ``--isolated`` as a parameter, which will cause each

  selected test to be run independently. This can be useful to both workaround
  isolation bugs and detect tests that can not be run independently.
  (Robert Collins)

4 files changed, 73 insertions, 2 deletions

diff --git a/NEWS b/NEWS
index 663d563..d079ac6 100644
--- a/NEWS
+++ b/NEWS
@@ -5,6 +5,14 @@ testrepository release notes
 NEXT (In development)
 +++++++++++++++++++++
 
+CHANGES
+-------
+
+* ``run`` now accepts ``--isolated`` as a parameter, which will cause each
+  selected test to be run independently. This can be useful to both workaround
+  isolation bugs and detect tests that can not be run independently.
+  (Robert Collins)
+
 INTERNALS
 ---------
 
diff --git a/doc/MANUAL.txt b/doc/MANUAL.txt
index 28b286b..d0b298b 100644
--- a/doc/MANUAL.txt
+++ b/doc/MANUAL.txt
@@ -366,6 +366,21 @@ will perform that analysis for you. (This requires that your test runner is
    then either the isolation issue is racy, or it is a 3-or-more test
    isolation issue. Neither of those cases are automated today.
 
+Forcing isolation
+~~~~~~~~~~~~~~~~~
+
+Sometimes it is useful to force a separate test runner instance for each test
+executed. The ``--isolated`` flag will cause testr to execute a separate runner
+per test::
+
+  $ testr run --isolated
+
+In this mode testr first determines tests to run (either automatically listed,
+using the failing set, or a user supplied load-list), and then spawns one test
+runner per test it runs. To avoid cross-test-runner interactions concurrency
+is disabled in this mode. ``--analyze-isolation`` supercedes ``--isolated`` if
+they are both supplied.
+
 Repositories
 ~~~~~~~~~~~~
 
diff --git a/testrepository/commands/run.py b/testrepository/commands/run.py
index a18c235..7b6cd40 100644
--- a/testrepository/commands/run.py
+++ b/testrepository/commands/run.py
@@ -143,6 +143,9 @@ class run(Command):
         optparse.Option("--analyze-isolation", action="store_true",
             default=False,
             help="Search the last test run for 2-test test isolation interactions."),
+        optparse.Option("--isolated", action="store_true",
+            default=False,
+            help="Run each test id in a separate test runner."),
         ]
     args = [StringArgument('testfilters', 0, None), DoubledashArgument(),
         StringArgument('testargs', 0, None)]
@@ -192,7 +195,22 @@ class run(Command):
             if not self.ui.options.analyze_isolation:
                 cmd = testcommand.get_run_command(ids, self.ui.arguments['testargs'],
                     test_filters = filters)
-                return self._run_tests(cmd)
+                if self.ui.options.isolated:
+                    result = 0
+                    cmd.setUp()
+                    try:
+                        ids = cmd.list_tests()
+                    finally:
+                        cmd.cleanUp()
+                    for test_id in ids:
+                        cmd = testcommand.get_run_command([test_id],
+                            self.ui.arguments['testargs'], test_filters=filters)
+                        run_result = self._run_tests(cmd)
+                        if run_result > result:
+                            result = run_result
+                    return result
+                else:
+                    return self._run_tests(cmd)
             else:
                 # Where do we source data about the cause of conflicts.
                 # XXX: Should instead capture the run id in with the failing test
@@ -329,7 +347,8 @@ class run(Command):
             def run_tests():
                 run_procs = [('subunit', ReturnCodeToSubunit(proc)) for proc in cmd.run_tests()]
                 options = {}
-                if self.ui.options.failing or self.ui.options.analyze_isolation:
+                if (self.ui.options.failing or self.ui.options.analyze_isolation
+                    or self.ui.options.isolated):
                     options['partial'] = True
                 load_ui = decorator.UI(input_streams=run_procs, options=options,
                     decorated=self.ui)
diff --git a/testrepository/tests/commands/test_run.py b/testrepository/tests/commands/test_run.py
index 3168e94..da94ca2 100644
--- a/testrepository/tests/commands/test_run.py
+++ b/testrepository/tests/commands/test_run.py
@@ -446,6 +446,35 @@ class TestCommand(ResourcedTestCase):
             ], ui.outputs)
         self.assertEqual(0, result)
 
+    def test_isolated_runs_multiple_processes(self):
+        ui, cmd = self.get_test_ui_and_cmd(options=[('isolated', True)])
+        cmd.repository_factory = memory.RepositoryFactory()
+        self.setup_repo(cmd, ui)
+        self.set_config(
+            '[DEFAULT]\ntest_command=foo $IDLIST $LISTOPT\n'
+            'test_id_option=--load-list $IDFILE\n'
+            'test_list_option=--list\n')
+        params, capture_ids = self.capture_ids(list_result=['ab', 'cd', 'ef'])
+        self.useFixture(MonkeyPatch(
+            'testrepository.testcommand.TestCommand.get_run_command',
+            capture_ids))
+        cmd_result = cmd.execute()
+        self.assertEqual([
+            ('results', Wildcard),
+            ('summary', True, 0, -3, None, None, [('id', 1, None)]),
+            ('results', Wildcard),
+            ('summary', True, 0, 0, None, None, [('id', 2, None)]),
+            ('results', Wildcard),
+            ('summary', True, 0, 0, None, None, [('id', 3, None)]),
+            ], ui.outputs)
+        self.assertEqual(0, cmd_result)
+        # once to list, then 3 each executing one test.
+        self.assertThat(params, HasLength(4)) 
+        self.assertThat(params[0][1], Equals(None))
+        self.assertThat(params[1][1], Equals(['ab']))
+        self.assertThat(params[2][1], Equals(['cd']))
+        self.assertThat(params[3][1], Equals(['ef']))
+
 
 def read_all(stream):
     return stream.read()