Add unit tests for overrides in multi-repo workflow

unittests/repo_test_util.py

 # Copyright 2016 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 """Utilities for testing with real repos (e.g. git)."""
 
 
 import contextlib
 import os
 import shutil
@@ skipping 159 matching lines @@
       subprocess.check_call(['git', 'branch', '-f', 'origin/master', rev])
     return {
         'root': repo['root'],
         'revision': rev,
         'spec': repo['spec'],
         'author_name': author_name,
         'author_email': author_email,
         'message': message,
     }
 
+  def train_recipes(self, repo, overrides=None):
+    """Trains recipe simulation tests in given repo.
+
+    Arguments:
+      repo(dict): one of the repos returned by |repo_setup|
+      overrides: iterable((str, str)): optional list of overrides
+          first element of the tuple is the module name, and second
+          is the overriding path
+    """
+    if not overrides:
+      overrides = []
+    with in_directory(repo['root']):
+      args = [
+          sys.executable, self._recipe_tool,
+          '--package', os.path.join(
+              repo['root'], 'infra', 'config', 'recipes.cfg'),
+      ]
+      for repo, path in overrides:
+        args.extend(['-O', '%s=%s' % (repo, path)])
+      args.extend([
+          'simulation_test',
+          'train',
+      ])
+      subprocess.check_output(args, stderr=subprocess.STDOUT)
+
   def update_recipe(self, repo, name, deps, calls):
     """Updates or creates a recipe in given repo.
     Commits the change.
 
     Arguments:
       repo(dict): one of the repos returned by |repo_setup|
       name(str): name of the recipe (without .py)
       deps(iterable(str)): list of recipe dependencies (DEPS)
       calls(iterable((str, str))): list of calls to recipe module
           methods to make in the recipe; first element of the tuple
           is the module name, and second is the method name
 
     """
     with in_directory(repo['root']):
       recipes_dir = 'recipes'
       if not os.path.exists(recipes_dir):
         os.makedirs(recipes_dir)
       with open(os.path.join(recipes_dir, '%s.py' % name), 'w') as f:
         f.write('\n'.join([
           'DEPS = %r' % deps,
           '',
           'def RunSteps(api):',
         ] + ['  api.%s.%s()' % c for c in calls] + [
           '',
           'def GenTests(api):',
           '  yield api.test("basic")',
         ]))
 
-      subprocess.check_output([
-          sys.executable, self._recipe_tool,
-          '--package', os.path.join(
-              repo['root'], 'infra', 'config', 'recipes.cfg'),
-          'simulation_test',
-          'train',
-      ])
+      self.train_recipes(repo)
 
       subprocess.check_call(
           ['git', 'add', os.path.join(recipes_dir, '%s.py' % name)])
       subprocess.check_call(
           ['git', 'add', os.path.join(recipes_dir, '%s.expected' % name)])
       return self.commit_in_repo(repo, message='recipe update')
 
   def update_recipe_module(self, repo, name, methods):
     """Updates or creates a recipe module in given repo.
     Commits the change.
@@ skipping 44 matching lines @@
       message = ' '.join(
         ['update %r recipe_module: ' % name] +
         ['%s(%s)' % t for t in methods.iteritems()]
       )
       return self.commit_in_repo(repo, message)
 
   def reset_repo(self, repo, revision):
     """Resets repo contents to given revision."""
     with in_directory(repo['root']):
       subprocess.check_output(['git', 'reset', '--hard', revision])