Log the GN args again in `mb gen`.

tools/mb/mb_unittest.py

 #!/usr/bin/python
 # Copyright 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.
 
 """Tests for mb.py."""
 
 import json
 import StringIO
 import os
@@ skipping 38 matching lines @@
   def MaybeMakeDirectory(self, path):
     self.files[path] = True
 
   def PathJoin(self, *comps):
     return self.sep.join(comps)
 
   def ReadFile(self, path):
     return self.files[path]
 
   def WriteFile(self, path, contents, force_verbose=False):
+    if self.args.dryrun or self.args.verbose or force_verbose:
+      self.Print('\nWriting """\\\n%s""" to %s.\n' % (contents, path))
     self.files[path] = contents
 
   def Call(self, cmd, env=None, buffer_output=True):
     if env:
       self.cross_compile = env.get('GYP_CROSSCOMPILE')
     self.calls.append(cmd)
     if self.cmds:
       return self.cmds.pop(0)
     return 0, '', ''
 
@@ skipping 229 matching lines @@
     out = json.loads(mbw.files['/tmp/out.json'])
     self.assertEqual(out, {
       'status': 'No dependency',
       'compile_targets': [],
       'test_targets': [],
     })
 
   def test_gn_gen(self):
     mbw = self.fake_mbw()
     self.check(['gen', '-c', 'gn_debug_goma', '//out/Default', '-g', '/goma'],
-               mbw=mbw, ret=0,
-               out=('/fake_src/buildtools/linux64/gn gen //out/Default '
-                    '--check\n'))
+               mbw=mbw, ret=0)
     self.assertMultiLineEqual(mbw.files['/fake_src/out/Default/args.gn'],
                               ('goma_dir = "/goma"\n'
                                'is_debug = true\n'
                                'use_goma = true\n'))
 
+    # Make sure we log both what is written to args.gn and the command line.
+    self.assertIn('Writing """', mbw.out)
+    self.assertIn('/fake_src/buildtools/linux64/gn gen //out/Default --check',
+                  mbw.out)
+
     mbw = self.fake_mbw(win32=True)
     self.check(['gen', '-c', 'gn_debug_goma', '-g', 'c:\\goma', '//out/Debug'],
-               mbw=mbw, ret=0,
-               out=('c:\\fake_src\\buildtools\\win\\gn.exe gen //out/Debug '
-                    '--check\n'))
+               mbw=mbw, ret=0)
     self.assertMultiLineEqual(mbw.files['c:\\fake_src\\out\\Debug\\args.gn'],
                               ('goma_dir = "c:\\\\goma"\n'
                                'is_debug = true\n'
                                'use_goma = true\n'))
+    self.assertIn('c:\\fake_src\\buildtools\\win\\gn.exe gen //out/Debug '
+                  '--check\n', mbw.out)
 
     mbw = self.fake_mbw()
     self.check(['gen', '-m', 'fake_master', '-b', 'fake_gn_args_bot',
                 '//out/Debug'],
                mbw=mbw, ret=0)
     self.assertEqual(
         mbw.files['/fake_src/out/Debug/args.gn'],
         'import("//build/args/bots/fake_master/fake_gn_args_bot.gn")\n')
 
 
@@ skipping 128 matching lines @@
     self.check(['validate'], mbw=mbw, ret=0)
 
   def test_bad_validate(self):
     mbw = self.fake_mbw()
     mbw.files[mbw.default_config] = TEST_BAD_CONFIG
     self.check(['validate'], mbw=mbw, ret=1)
 
 
 if __name__ == '__main__':
   unittest.main()