Made Pixel tests functional. Captures tab content and compares to ref image

content/test/gpu/gpu_tests/pixel.py

 # Copyright (c) 2012 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.
+from datetime import datetime
+import glob
+import os
+import re
+
 from telemetry import test
+from telemetry.core.backends import png_bitmap
 from telemetry.page import page_test
 
+test_data_dir = os.path.abspath(os.path.join(

[Zhenyao Mo, 2013/09/05 00:23:14]

The reason we use a passed in dir is because the src folder will be blown away
from time to time (hard clobber), so you don't want to put your ref images
there.  Put it somewhere more stable.

+    os.path.dirname(__file__), '..', '..', 'data', 'gpu'))
+
+generated_data_dir = os.path.join(test_data_dir, 'generated')
+ref_image_dir = os.path.join(test_data_dir, 'gpu_reference')

[Ken Russell (switch to Gerrit), 2013/09/05 00:27:04]

The current harness is careful not to dump images into the source tree,
presumably to avoid collisions with any newly created files. Shouldn't the new
harness do the same?

 
 class PixelTestFailure(Exception):
   pass
 
-
 class PixelValidator(page_test.PageTest):
   def __init__(self):
     super(PixelValidator, self).__init__('ValidatePage')
 
+  def CustomizeBrowserOptions(self, options):
+    options.AppendExtraBrowserArg('--enable-gpu-benchmarking')
+
   def ValidatePage(self, page, tab, results):
-    # TODO(bajones): Grab screenshot, compare to reference.
-    # page.reference_image
-    pass
+    if not tab.screenshot_supported:
+      raise page_test.Failure("Browser does not support screenshot capture")
 
+    screenshot = tab.Screenshot(5)
+
+    if not screenshot:
+      raise page_test.Failure("Could not capture screenshot")
+
+    image_name = PixelValidator.UrlToImageName(page.url)
+
+    ref_png = PixelValidator.GetReferenceImage(image_name, page.revision,
+        screenshot)
+
+    # Test new snapshot against existing reference image
+    if not ref_png.IsEqual(screenshot, tolerance=2):
+      PixelValidator.WriteErrorImages(image_name, page.revision, screenshot,
+          ref_png)
+      raise page_test.Failure("Reference image did not match captured screen")
+
+  @staticmethod
+  def UrlToImageName(url):
+    image_name = re.sub(r'^(http|https|file)://(/*)', '', url)
+    image_name = re.sub(r'\.\./', '', image_name)
+    image_name = re.sub(r'(\.|/|-)', '_', image_name)
+    return image_name
+
+  @staticmethod
+  def DeleteOldReferenceImages(ref_image_path, cur_revision):
+    if not cur_revision:
+      return
+
+    old_revisions = glob.glob(ref_image_path + "__rev_*.png")
+    for rev_path in old_revisions:
+      m = re.match(r'^.*__rev_(\d+)\.png$', rev_path)
+      if m and int(m.group(1)) < cur_revision:
+        print 'Found deprecated reference image. Deleting rev ' + m.group(1)
+        os.remove(rev_path)
+
+  @staticmethod
+  def GetReferenceImage(image_name, cur_revision, screenshot):
+    if not cur_revision:
+      cur_revision = 0
+
+    image_path = os.path.join(ref_image_dir, image_name)
+
+    PixelValidator.DeleteOldReferenceImages(image_path, cur_revision)
+
+    image_path = image_path + '__rev_' + str(cur_revision) + '.png'
+
+    try:
+      ref_png = png_bitmap.PngBitmap.FromFile(image_path)
+    except IOError:
+      ref_png = None
+
+    if ref_png:
+      return ref_png
+
+    print 'Reference image not found. Writing tab contents as reference.'
+
+    PixelValidator.WriteImage(image_path, screenshot)
+    return screenshot
+
+  @staticmethod
+  def WriteErrorImages(image_name, cur_revision, screenshot, ref_png):
+    capture_time = datetime.now()
+    full_image_name = image_name + '__rev_' + str(cur_revision)
+    full_image_name = full_image_name + capture_time.strftime("__%b%d_%H_%M_%S")
+    full_image_name = full_image_name + '.png'
+
+    PixelValidator.WriteImage(
+        os.path.join(generated_data_dir, 'FAIL_' + full_image_name), screenshot)
+
+    diff_png = screenshot.Diff(ref_png)
+    PixelValidator.WriteImage(
+        os.path.join(generated_data_dir, 'DIFF_' + full_image_name), diff_png)
+
+  @staticmethod
+  def WriteImage(image_path, png_image):
+    output_dir = os.path.dirname(image_path)
+    if not os.path.exists(output_dir):
+      os.makedirs(output_dir)
+
+    png_image.WriteFile(image_path)
 
 class Pixel(test.Test):
   enabled = False
   test = PixelValidator
   page_set = 'page_sets/pixel_tests.json'