Adds the ability to run pure Go unit tests in the Mojo test suite.

mojo/tools/run_pure_go_tests.py

+#!/usr/bin/env python
+# Copyright (c) 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import argparse
+import os
+import subprocess
+import sys
+

[ppi, 2015/10/05 21:49:58]

I think the style guide wants two empty lines here.

[rudominer, 2015/10/05 23:08:13]

Done. But now the two empty lines are lines 12 and 13 below.

+def main():
+  parser = argparse.ArgumentParser()

[ppi, 2015/10/05 21:49:58]

Please add a desription string, ie.
argparse.ArgumentParser(description="describe what it does")

[rudominer, 2015/10/05 23:08:13]

Done.

+  parser.add_argument('--go_tool')

[ppi, 2015/10/05 21:49:58]

I think we prefer "dash-only" arguments: --go-tool.

[ppi, 2015/10/05 21:49:58]

If that is a required argument I'd make it positional, ie. remove the "--" from
the name. this also removes the need for the assert later. Please add a "help"
string explaining the usage.

[rudominer, 2015/10/05 23:08:12]

Done.

[rudominer, 2015/10/05 23:08:13]

Done.

[rudominer, 2015/10/05 23:08:13]

Done.

+  args = parser.parse_args()
+  go_tool = args.go_tool
+  assert go_tool is not None
+  env = os.environ.copy()
+  env['GOROOT'] = os.path.dirname(os.path.dirname(go_tool))
+
+  saved_cwd = os.getcwd()
+
+  test_dir_list = [
+      # TODO(rudominer) Add paths to go directories with tests.
+      #os.path.join('mojom', 'mojom_parser', 'lexer'),
+  ]
+
+  for test_dir in test_dir_list:
+    os.chdir(test_dir)

[ppi, 2015/10/05 21:49:58]

There is an issue here that as "test_dir" is relative, it will work correctly
only in the first run of the loop. We can

 a) move from subprocess.call to bare Popen, which accepts the cwd= argument (so
that we don't need to modify the working directory of ourselves)
 b) ensure we restore the original cwd at the end of each loop run
 c) ensure the test_dirs are absolute paths

As much as bare Popen is ugly to work with, I'd probably go with it.

[rudominer, 2015/10/05 23:08:13]

Thank you for catching this. I went with your option (c) if that is ok with you.

+    print "Running Go tests in %s..." % test_dir
+    call_result = subprocess.call([go_tool, "test"], env=env)
+    if call_result:
+      os.chdir(saved_cwd )
+      return call_result
+
+  os.chdir(saved_cwd )

[ppi, 2015/10/05 21:49:58]

remove the space after "saved_cwd".

[rudominer, 2015/10/05 23:08:13]

Done.

+
+if __name__ == '__main__':
+  sys.exit(main())