Fix up regression tester

* Clean up to support pydoc
* Support -h
* Make it actually work
* Improve docstrings
* Add copyright

Change-Id: I977df71e8213e39e9eebf9cc56b2dd7625959870

tools/regression_tester.py

@@ -1,81 +1,109 @@
 #!/usr/bin/env python
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright (c) 2013 OpenStack Foundation
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
 
 """Tool for checking if patch contains a regression test.
 
-Pass in gerrit review number as parameter, tool will download branch and run
+By default runs against current patch but can be set to use any gerrit review
-modified tests without bug fix.
+as specified by change number (uses 'git review -d').
+
+Idea: take tests from patch to check, and run against code from previous patch.
+If new tests pass, then no regression test, if new tests fails against old code
+then either
+* new tests depend on new code and cannot confirm regression test is valid
+  (false positive)
+* new tests detects the bug being fixed (detect valid regression test)
+Due to the risk of false positives, the results from this need some human
+interpretation.
 """
 
+import optparse
 import string
 import subprocess
 import sys
 
-gerrit_number = None
-
-#TODO(jogo) use proper optParser
-if len(sys.argv) == 2:
-    gerrit_number = sys.argv[1]
-else:
-    gerrit_number = None
-    print ("no gerrit review number specified, running on latest commit"
-            "on current branch.")
-
 
 def run(cmd, fail_ok=False):
     print "running: %s" % cmd
-    try:
+    obj = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
-        rval = subprocess.check_output(cmd, shell=True)
+                           shell=True)
-    except subprocess.CalledProcessError:
+    obj.wait()
-        if not fail_ok:
+    if obj.returncode != 0 and not fail_ok:
-            print "The command above terminated with an error."
+        print "The above command terminated with an error."
-            sys.exit(1)
+        sys.exit(obj.returncode)
-        pass
+    return obj.stdout.read()
-    return rval
 
 
-test_works = False
+def main():
+    usage = """
+    Tool for checking if a patch includes a regression test.
 
-if gerrit_number:
+    Usage: %prog [options]"""
-    original_branch = run("git rev-parse --abbrev-ref HEAD")
+    parser = optparse.OptionParser(usage)
-    run("git review -d %s" % gerrit_number)
+    parser.add_option("-r", "--review", dest="review",
+                      help="gerrit review number to test")
+    (options, args) = parser.parse_args()
+    if options.review:
+        original_branch = run("git rev-parse --abbrev-ref HEAD")
+        run("git review -d %s" % options.review)
+    else:
+        print ("no gerrit review number specified, running on latest commit"
+               "on current branch.")
 
-# run new tests with old code
-run("git checkout HEAD^ nova")
-run("git checkout HEAD nova/tests")
-
-# identify which tests have changed
-tests = run("git whatchanged --format=oneline -1 | grep \"nova/tests\" "
-            "| cut -f2").split()
-test_list = []
-for test in tests:
-    test_list.append(string.replace(test[0:-3], '/', '.'))
-
-if test_list == []:
     test_works = False
-    expect_failure = ""
-else:
-    # run new tests, expect them to fail
-    expect_failure = run(("tox -epy27 %s 2>&1" % string.join(test_list)),
-                         fail_ok=True)
-    if "FAILED (id=" in expect_failure:
-        test_works = True
 
-# cleanup
+    # run new tests with old code
-run("git checkout HEAD nova")
+    run("git checkout HEAD^ nova")
-if gerrit_number:
+    run("git checkout HEAD nova/tests")
-    new_branch = run("git status | head -1 | cut -d ' ' -f 4")
-    run("git checkout %s" % original_branch)
-    run("git branch -D %s" % new_branch)
 
+    # identify which tests have changed
+    tests = run("git whatchanged --format=oneline -1 | grep \"nova/tests\" "
+                "| cut -f2").split()
+    test_list = []
+    for test in tests:
+        test_list.append(string.replace(test[0:-3], '/', '.'))
+
+    if test_list == []:
+        test_works = False
+        expect_failure = ""
+    else:
+        # run new tests, expect them to fail
+        expect_failure = run(("tox -epy27 %s 2>&1" % string.join(test_list)),
+                             fail_ok=True)
+        if "FAILED (id=" in expect_failure:
+            test_works = True
+
+    # cleanup
+    run("git checkout HEAD nova")
+    if options.review:
+        new_branch = run("git status | head -1 | cut -d ' ' -f 4")
+        run("git checkout %s" % original_branch)
+        run("git branch -D %s" % new_branch)
 
-if test_works:
     print expect_failure
     print ""
     print "*******************************"
-    print "FOUND a regression test"
+    if test_works:
-else:
+        print "FOUND a regression test"
-    print expect_failure
+    else:
-    print ""
+        print "NO regression test"
-    print "*******************************"
+        sys.exit(1)
-    print "NO regression test"
+
-    sys.exit(1)
+
+if __name__ == "__main__":
+    main()