Support for ignore checkstyle files

This CL extends checkstyle check to search for IGNORE_CHECKSTYLE
files in folders which marks them as excluded from checkstyle,
including their sub folders

Change-Id: Id2390bb2a92e03f49c0014888e21549279e4bab6

tools/checkstyle/checkstyle.py

@@ -28,6 +28,30 @@ import tempfile
 import xml.dom.minidom
 import gitlint.git as git
 
+def _FindFoldersContaining(root, wanted):
+  """Searches recursively from root to find directories that has a file with
+  the given name.
+
+  Args:
+    root: Root folder to start the search from.
+    wanted: The filename that we are looking for.
+
+  Returns:
+    List of folders that has a file with the given name
+  """
+
+  if os.path.islink(root):
+    return []
+  result = []
+  for fileName in os.listdir(root):
+    filePath = os.path.join(root, fileName)
+    if os.path.isdir(filePath):
+      subResult = _FindFoldersContaining(filePath, wanted)
+      result.extend(subResult)
+    else:
+      if fileName == wanted:
+        result.append(root)
+  return result
 
 MAIN_DIRECTORY = os.path.normpath(os.path.dirname(__file__))
 CHECKSTYLE_JAR = os.path.join(MAIN_DIRECTORY, 'checkstyle.jar')
@@ -37,7 +61,8 @@ FORCED_RULES = ['com.puppycrawl.tools.checkstyle.checks.imports.ImportOrderCheck
 SKIPPED_RULES_FOR_TEST_FILES = ['com.puppycrawl.tools.checkstyle.checks.javadoc.JavadocTypeCheck',
                                 'com.puppycrawl.tools.checkstyle.checks.javadoc.JavadocMethodCheck']
 SUBPATH_FOR_TEST_FILES = ['/tests/', '/test/']
-SUBPATH_FOR_TEST_DATA_FILES = ['src/tests/test-data/']
+SUBPATH_FOR_TEST_DATA_FILES = _FindFoldersContaining(os.path.dirname(os.getcwd()),
+                                                     "IGNORE_CHECKSTYLE")
 ERROR_UNCOMMITTED = 'You need to commit all modified files before running Checkstyle\n'
 ERROR_UNTRACKED = 'You have untracked java files that are not being checked:\n'