Make CheckLicense() to not trigger on empty files.

This is especially annoying on empty __init__.py files.

TEST=new unit test
BUG=none

Review URL: http://codereview.chromium.org/4310001

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@64904 0039d316-1c4b-4281-b951-d872f2087c98

presubmit_canned_checks.py

@@ -275,13 +275,16 @@ def CheckLongLines(input_api, output_api, maxlen=80, source_file_filter=None):
     return []
 
 
-def CheckLicense(input_api, output_api, license, source_file_filter=None):
+def CheckLicense(input_api, output_api, license, source_file_filter=None,
+    accept_empty_files=True):
   """Verifies the license header.
   """
   license_re = input_api.re.compile(license, input_api.re.MULTILINE)
   bad_files = []
   for f in input_api.AffectedSourceFiles(source_file_filter):
     contents = input_api.ReadFile(f, 'rb')
+    if accept_empty_files and not contents:
+      continue
     if not license_re.search(contents):
       bad_files.append(f.LocalPath())
   if bad_files:

tests/presubmit_unittest.py

@@ -1386,7 +1386,7 @@ class CannedChecksUnittest(PresubmitTestsBase):
                          'svn:eol-style', 'LF', '', False,
                          presubmit.OutputApi.PresubmitNotifyResult, True)
 
-  def _LicenseCheck(self, text, license, committing, expected_result):
+  def _LicenseCheck(self, text, license, committing, expected_result, **kwargs):
     change = self.mox.CreateMock(presubmit.SvnChange)
     change.scm = 'svn'
     input_api = self.MockInputApi(change, committing)
@@ -1398,7 +1398,8 @@ class CannedChecksUnittest(PresubmitTestsBase):
 
     self.mox.ReplayAll()
     result = presubmit_canned_checks.CheckLicense(
-                 input_api, presubmit.OutputApi, license, 42)
+                 input_api, presubmit.OutputApi, license, source_file_filter=42,
+                 **kwargs)
     if expected_result:
       self.assertEqual(len(result), 1)
       self.assertEqual(result[0].__class__, expected_result)
@@ -1446,6 +1447,14 @@ class CannedChecksUnittest(PresubmitTestsBase):
     self._LicenseCheck(text, license, False,
                        presubmit.OutputApi.PresubmitNotifyResult)
 
+  def testCheckLicenseEmptySuccess(self):
+    text = ''
+    license = (
+        r".*? Copyright \(c\) 2037 Nobody." "\n"
+        r".*? All Rights Reserved\." "\n"
+    )
+    self._LicenseCheck(text, license, True, None, accept_empty_files=True)
+
   def testCannedCheckSvnAccidentalSubmission(self):
     modified_dir_file = 'foo/'
     accidental_submssion_file = 'foo/bar.cc'