Refactor PDFium python test utilities.

testing/tools/pngdiffer.py

Index: testing/tools/pngdiffer.py
diff --git a/testing/tools/pngdiffer.py b/testing/tools/pngdiffer.py
new file mode 100755
index 0000000000000000000000000000000000000000..1891044481c3f0b7f56d913ac92e055f09ddeb7c
--- /dev/null
+++ b/testing/tools/pngdiffer.py
@@ -0,0 +1,94 @@
+#!/usr/bin/env python
+# Copyright 2015 The PDFium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os
+import subprocess
+import sys
+
+class PNGDiffer():
+  def __init__(self, os_name, pdfium_diff_path):
+    self.pdfium_diff_path = pdfium_diff_path
+    self.actual_template = '.pdf.%d.png'

[Lei Zhang, 2015/04/02 23:16:20]

this can be a class constant

[Tom Sepez, 2015/04/03 18:13:14]

Done.

+    self.expected_template = '_expected' + self.actual_template
+    # os_name to be used shortly for platform-specifc result files.
+
+  def HasDifferences(self, input_filename, source_dir, working_dir):
+    input_root, _ = os.path.splitext(input_filename)
+    actual_path_template = os.path.join(
+        working_dir, input_root + self.actual_template)
+    expected_path_template = os.path.join(
+        source_dir, input_root + self.expected_template)
+    i = 0
+    try:
+      while True:
+        actual_path = actual_path_template % i;
+        expected_path = expected_path_template % i;
+        if not os.path.exists(expected_path):
+          if i == 0:
+            print "WARNING: no expected results files for " + input_filename
+          break
+        print "Checking " + actual_path
+        sys.stdout.flush()
+        subprocess.check_call(
+            [self.pdfium_diff_path, expected_path, actual_path])
+        i += 1
+    except subprocess.CalledProcessError as e:
+      print "FAILURE: " + input_filename + "; " + str(e)
+      return True
+    return False
+
+
+# Testing.

[Lei Zhang, 2015/04/02 23:16:20]

Other python projects within the chromium-sphere puts tests for foo.py in
foo_test.py.

[Tom Sepez, 2015/04/03 18:13:15]

Comment is misleading.  This makes a command-line utility out of the module, but
its only used by the developer for his own ... testing. 
I've removed this as the marginal benefit isn't worth the cost of code. 

+def main(argv):
+  if sys.platform.startswith('linux'):

[Lei Zhang, 2015/04/02 23:16:20]

This can go in to common.py since we use it everywhere.

[Tom Sepez, 2015/04/03 18:13:14]

Done.

+    os_name = 'linux'
+  elif sys.platform.startswith('win'):
+    os_name = 'win'
+  elif sys.platform.startswith('darwin'):
+    os_name = 'mac'
+  else:
+    print 'Confused, can not determine OS, aborting.'
+    return 1
+
+  if len(argv) != 4:
+    print "usage: %s <filename> <source-dir> <working-dir>" % argv[0]
+    return 1
+
+  # Expect |my_dir| to be .../pdfium/testing/tools.
+  my_dir = os.path.dirname(os.path.realpath(__file__))
+  testing_dir = os.path.dirname(my_dir)
+  pdfium_dir = os.path.dirname(testing_dir)
+  if (os.path.basename(my_dir) != 'tools' or
+      os.path.basename(testing_dir) != 'testing'):
+    print 'Confused, can not find pdfium root directory, aborting.'
+    return 1
+
+  # Find path to build directory.  This depends on whether this is a
+  # standalone build vs. a build as part of a chromium checkout. For
+  # standalone, we expect a path like .../pdfium/out/Debug, but for
+  # chromium, we expect a path like .../src/out/Debug two levels
+  # higher (to skip over the third_party/pdfium path component under
+  # which chromium sticks pdfium).
+  base_dir = pdfium_dir
+  one_up_dir = os.path.dirname(base_dir)
+  two_up_dir = os.path.dirname(one_up_dir)
+  if (os.path.basename(two_up_dir) == 'src' and
+      os.path.basename(one_up_dir) == 'third_party'):
+    base_dir = two_up_dir
+  build_dir = os.path.join(base_dir, 'out', 'Debug')
+
+  # Compiled binaries are found under the build path.
+  pdfium_diff_path = os.path.join(build_dir, 'pdfium_diff')
+  if sys.platform.startswith('win'):
+    pdfium_diff_path = pdfium_diff_path + '.exe'
+
+  differ = PNGDiffer(os_name, pdfium_diff_path)
+  if differ.HasDifferences(argv[1], argv[2], argv[3]):
+    print "Returned true"
+
+  return 0
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv))