Check for system include paths by looking at clang's HeaderSearchOptions,

tools/clang/translation_unit/test_translation_unit.py

Index: tools/clang/translation_unit/test_translation_unit.py
diff --git a/tools/clang/translation_unit/test_translation_unit.py b/tools/clang/translation_unit/test_translation_unit.py
index a8e8f6865af2f9269420d1cb9683b7db14bb6d58..46576b03e35e981bfb547159a4d1f05de689cf8e 100755
--- a/tools/clang/translation_unit/test_translation_unit.py
+++ b/tools/clang/translation_unit/test_translation_unit.py
@@ -15,11 +15,10 @@ import subprocess
 import sys
 
 
-def _GenerateCompileCommands(files):
+def _GenerateCompileCommands(template_path, test_files_dir):
   """Returns a JSON string containing a compilation database for the input."""
-  return json.dumps([{'directory': '.',
-                      'command': 'clang++ -fsyntax-only -std=c++11 -c %s' % f,
-                      'file': f} for f in files], indent=2)
+  with open(template_path) as fh:
+    return fh.read().replace('$test_files_dir', test_files_dir)
 
 
 def _NumberOfTestsToString(tests):
@@ -38,11 +37,13 @@ def main():
       tools_clang_directory, 'translation_unit', 'test_files')
   compile_database = os.path.join(test_directory_for_tool,
                                   'compile_commands.json')
+  compile_database_template = compile_database + '.template'
   source_files = glob.glob(os.path.join(test_directory_for_tool, '*.cc'))
 
   # Generate a temporary compilation database to run the tool over.
   with open(compile_database, 'w') as f:
-    f.write(_GenerateCompileCommands(source_files))
+    f.write(_GenerateCompileCommands(compile_database_template,
+                                     test_directory_for_tool))
 
   args = ['python',
           os.path.join(tools_clang_scripts_directory, 'run_tool.py'),
@@ -68,13 +69,9 @@ def main():
       actual_output = f.readlines()
     has_same_filepaths = True
     for expected_line, actual_line in zip(expected_output, actual_output):
-      if '//' in actual_output:
-        if actual_output.split('//')[1] != expected_output:
-          sys.stdout.write('expected: %s' % expected_output)
-          sys.stdout.write('actual: %s' % actual_output.split('//')[1])
-          break
-        else:
-          continue
+      if '//' in actual_line:
+        actual_line = '//' + actual_line.split('//')[1]
+
       if ntpath.basename(expected_line) != ntpath.basename(actual_line):
         sys.stdout.write('expected: %s' % ntpath.basename(expected_line))
         sys.stdout.write('actual: %s' % ntpath.basename(actual_line))