Loading screenshots and simple 1-to-1 comparison of screenshots

chrome/browser/chromeos/login/screenshot_tester.cc

 // Copyright 2014 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.
 
 #include "chrome/browser/chromeos/login/screenshot_tester.h"
 
 #include "ash/shell.h"
 #include "base/base_export.h"
 #include "base/bind_internal.h"
 #include "base/command_line.h"
+#include "base/logging.h"
 #include "base/memory/weak_ptr.h"
 #include "base/prefs/pref_service.h"
 #include "base/run_loop.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/common/pref_names.h"
 #include "chromeos/chromeos_switches.h"
 #include "content/public/browser/browser_thread.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+#include "third_party/skia/include/core/SkCanvas.h"
 #include "ui/compositor/compositor_switches.h"
+#include "ui/gfx/codec/png_codec.h"
 #include "ui/gfx/image/image.h"
 #include "ui/snapshot/snapshot.h"
 
+namespace {
+
+// Sets test mode for screenshot testing.
+const char kTestMode[] = "test";
+
+// Sets update mode for screenshot testing.
+const char kUpdateMode[] = "update";
+
+}  // namespace
+
 namespace chromeos {
 
-ScreenshotTester::ScreenshotTester() : weak_factory_(this) {
+ScreenshotTester::ScreenshotTester() : test_mode_(false), weak_factory_(this) {
 }
 
 ScreenshotTester::~ScreenshotTester() {
 }
 
 bool ScreenshotTester::TryInitialize() {
   CommandLine& command_line = *CommandLine::ForCurrentProcess();
-  if (!command_line.HasSwitch(switches::kEnableScreenshotTesting))
+  if (!command_line.HasSwitch(switches::kEnableScreenshotTestingWithMode))
     return false;
   if (!command_line.HasSwitch(::switches::kEnablePixelOutputInTests) ||
       !command_line.HasSwitch(::switches::kUIEnableImplSidePainting)) {
     // TODO(elizavetai): make turning on --enable-pixel-output-in-tests
     // and --ui-enable-impl-side-painting automatical.
     LOG(ERROR) << "--enable-pixel-output-in-tests and "
                << "--ui-enable-impl-side-painting are required to take "
                << "screenshots";
     return false;
   }
-  if (!command_line.HasSwitch(switches::kScreenshotDestinationDir)) {
-    LOG(ERROR) << "No destination for screenshots specified";
-    return false;
+
+  std::string mode = command_line.GetSwitchValueASCII(
+      switches::kEnableScreenshotTestingWithMode);
+  if (mode != kUpdateMode && mode != kTestMode) {
+    CHECK(false) << "Invalid mode for screenshot testing: " << mode;
   }
-  screenshot_dest_ = command_line.GetSwitchValuePath(
-      chromeos::switches::kScreenshotDestinationDir);
+
+  if (!command_line.HasSwitch(chromeos::switches::kGoldenScreenshotsDir)) {
+    CHECK(false) << "No directory for golden screenshots specified";
+  }
+
+  golden_screenshots_dir_ =
+      command_line.GetSwitchValuePath(switches::kGoldenScreenshotsDir);
+
+  if (mode == kTestMode) {
+    test_mode_ = true;
+    if (!command_line.HasSwitch(switches::kArtifactsDir)) {
+      artifacts_dir_ = golden_screenshots_dir_;
+      LOG(WARNING)
+          << "No directory for artifact storing specified. Artifacts will be"
+          << "saved at golden screenshots directory.";
+    } else {
+      artifacts_dir_ = command_line.GetSwitchValuePath(switches::kArtifactsDir);
+    }
+  }
   return true;
 }
 
-void ScreenshotTester::Run(const std::string& file_name) {
-  TakeScreenshot();
-  PNGFile current_screenshot = screenshot_;
-  UpdateGoldenScreenshot(file_name, current_screenshot);
+void ScreenshotTester::Run(const std::string& test_name) {
+  test_name_ = test_name;
+  PNGFile current_screenshot = TakeScreenshot();
+  if (test_mode_) {
+    PNGFile golden_screenshot = LoadGoldenScreenshot();
+    VLOG(0) << "Loaded golden screenshot";
+    CompareScreenshots(golden_screenshot, current_screenshot);
+  } else {
+    UpdateGoldenScreenshot(current_screenshot);
+  }
 }
 
-void ScreenshotTester::UpdateGoldenScreenshot(const std::string& file_name,
-                                              PNGFile png_data) {
+void ScreenshotTester::UpdateGoldenScreenshot(PNGFile png_data) {
+  CHECK(SaveImage("golden_screenshot", golden_screenshots_dir_, png_data));
+}
+
+bool ScreenshotTester::SaveImage(const std::string& file_name,
+                                 const base::FilePath& screenshot_dir,
+                                 PNGFile png_data) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  base::FilePath screenshot_path =
+      screenshot_dir.AppendASCII(test_name_ + "_" + file_name + ".png");
   if (!png_data) {
     LOG(ERROR) << "Can't take a screenshot";
-    return;
+    return false;
   }
-  base::FilePath golden_screenshot_path =
-      screenshot_dest_.AppendASCII(file_name + ".png");
-  if (!base::CreateDirectory(golden_screenshot_path.DirName())) {
-    LOG(ERROR) << "Can't create a directory ";
-    return;
+  if (!base::CreateDirectory(screenshot_path.DirName())) {
+    LOG(ERROR) << "Can't create a directory "
+               << screenshot_path.DirName().value();
+    return false;
   }
   if (static_cast<size_t>(
-          base::WriteFile(golden_screenshot_path,
+          base::WriteFile(screenshot_path,
                           reinterpret_cast<char*>(&(png_data->data()[0])),
                           png_data->size())) != png_data->size()) {
-    LOG(ERROR) << "Can't save screenshot";
+    LOG(ERROR) << "Can't save screenshot " << file_name;
+    return false;
   }
-  VLOG(0) << "Golden screenshot updated successfully";
+  VLOG(0) << "Screenshot " << file_name << ".png saved successfully to "
+          << screenshot_dir.value();
+  return true;
 }
 
-void ScreenshotTester::ReturnScreenshot(PNGFile png_data) {
-  // TODO(elizavetai): rewrite this function so that TakeScreenshot
-  // could return a |PNGFile| -- current screenshot.
+void ScreenshotTester::ReturnScreenshot(const PNGFile& screenshot,
+                                        PNGFile png_data) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-  screenshot_ = png_data;
+  screenshot->data() = png_data->data();
   content::BrowserThread::PostTask(
       content::BrowserThread::UI, FROM_HERE, run_loop_quitter_);
 }
 
-void ScreenshotTester::TakeScreenshot() {
-  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+ScreenshotTester::PNGFile ScreenshotTester::TakeScreenshot() {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   aura::Window* primary_window = ash::Shell::GetPrimaryRootWindow();
   gfx::Rect rect = primary_window->bounds();
+  PNGFile screenshot = new base::RefCountedBytes;
   ui::GrabWindowSnapshotAsync(primary_window,
                               rect,
                               content::BrowserThread::GetBlockingPool(),
                               base::Bind(&ScreenshotTester::ReturnScreenshot,
-                                         weak_factory_.GetWeakPtr()));
+                                         weak_factory_.GetWeakPtr(),
+                                         screenshot));
   base::RunLoop run_loop;
   run_loop_quitter_ = run_loop.QuitClosure();
   run_loop.Run();
+  return screenshot;
+}
+
+ScreenshotTester::PNGFile ScreenshotTester::LoadGoldenScreenshot() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+
+  base::FilePath screenshot_path = golden_screenshots_dir_.AppendASCII(
+      test_name_ + "_golden_screenshot.png");
+  if (!base::PathExists(screenshot_path)) {
+    CHECK(false) << "Can't find a golden screenshot for this test";
+  }
+
+  int64 golden_screenshot_size;
+  base::GetFileSize(screenshot_path, &golden_screenshot_size);
+
+  if (golden_screenshot_size == -1) {
+    CHECK(false) << "Can't get golden screenshot size";
+  }
+  PNGFile png_data = new base::RefCountedBytes;
+  png_data->data().resize(golden_screenshot_size);
+  base::ReadFile(screenshot_path,
+                 reinterpret_cast<char*>(&(png_data->data()[0])),
+                 golden_screenshot_size);
+
+  return png_data;
+}
+
+void ScreenshotTester::CompareScreenshots(PNGFile model, PNGFile sample) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+
+  ASSERT_TRUE(model.get());
+  ASSERT_TRUE(sample.get());
+
+  SkBitmap model_bitmap;
+  SkBitmap sample_bitmap;
+  gfx::PNGCodec::Decode(reinterpret_cast<unsigned char*>(&(model->data()[0])),
+                        model->data().size(),
+                        &model_bitmap);
+  gfx::PNGCodec::Decode(reinterpret_cast<unsigned char*>(&(sample->data()[0])),
+                        sample->data().size(),
+                        &sample_bitmap);
+
+  ASSERT_EQ(model_bitmap.width(), sample_bitmap.width());
+  ASSERT_EQ(model_bitmap.height(), sample_bitmap.height());
+
+  bool screenshots_match = true;
+
+  SkCanvas diff_canvas(sample_bitmap);
+  for (int i = 0; i < model_bitmap.width(); i++)
+    for (int j = 0; j < model_bitmap.height(); j++) {
+      if (model_bitmap.getColor(i, j) == sample_bitmap.getColor(i, j)) {
+        diff_canvas.drawPoint(i, j, SK_ColorWHITE);
+      } else {
+        screenshots_match = false;
+        diff_canvas.drawPoint(i, j, SK_ColorRED);
+      }
+    }
+
+  if (!screenshots_match) {
+    CHECK(SaveImage("failed_screenshot", artifacts_dir_, sample));
+    gfx::PNGCodec::EncodeBGRASkBitmap(sample_bitmap, false, &sample->data());
+    CHECK(SaveImage("difference", artifacts_dir_, sample));
+    LOG(ERROR)
+        << "Screenshots testing failed. Screenshots differ in some pixels";
+    VLOG(0) << "Current screenshot and diff picture saved to "
+            << artifacts_dir_.value();
+  } else {
+    VLOG(0) << "Current screenshot matches the golden screenshot. Screenshot "
+               "testing passed.";
+  }
+  ASSERT_TRUE(screenshots_match);
 }
 
 }  // namespace chromeos