Add tests for PNGImageDecoder.

third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoderTest.cpp

Index: third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoderTest.cpp
diff --git a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoderTest.cpp b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoderTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..029cff3ca3299a31f8cfa64d0faf608203c5411e
--- /dev/null
+++ b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoderTest.cpp
@@ -0,0 +1,206 @@
+// Copyright 2016 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 "platform/image-decoders/png/PNGImageDecoder.h"
+
+#include "platform/image-decoders/ImageDecoderTestHelpers.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include <memory>
+
+namespace blink {
+
+namespace {
+
+std::unique_ptr<ImageDecoder> createDecoder(
+    ImageDecoder::AlphaOption alphaOption) {
+  return wrapUnique(
+      new PNGImageDecoder(alphaOption, ImageDecoder::ColorSpaceTransformed,
+                          ImageDecoder::targetColorSpaceForTesting(),
+                          ImageDecoder::noDecodedImageByteLimit));
+}
+
+std::unique_ptr<ImageDecoder> createDecoder() {
+  return createDecoder(ImageDecoder::AlphaNotPremultiplied);
+}
+
+std::unique_ptr<ImageDecoder> createDecoderWithPngData(const char* pngFile) {
+  auto decoder = createDecoder();
+  auto data = readFile(pngFile);
+  EXPECT_FALSE(data->isEmpty());
+  decoder->setData(data.get(), true);
+  return decoder;
+}
+
+void testSize(const char* pngFile, IntSize expectedSize) {
+  auto decoder = createDecoderWithPngData(pngFile);
+  EXPECT_TRUE(decoder->isSizeAvailable());
+  EXPECT_EQ(expectedSize, decoder->size());
+}
+
+void testRepetitionCount(const char* pngFile, int expectedRepetitionCount) {
+  auto decoder = createDecoderWithPngData(pngFile);
+  // Decoding the frame count sets the repetition count as well.
+  decoder->frameCount();
+  EXPECT_FALSE(decoder->failed());
+  EXPECT_EQ(expectedRepetitionCount, decoder->repetitionCount());
+}
+
+// Verify that the decoder can successfully decode the first frame when
+// initially only half of the frame data is received, resulting in a partially
+// decoded image, and then the rest of the image data is received. Verify that
+// the bitmap hashes of the two stages are different. This verifies that decoder
+// correctly keeps track of where it stopped decoding when the image was not
+// yet fully received.
+void testProgressiveDecodingContinuesAfterFullData(const char* pngFile,
+                                                   size_t offsetMidFirstFrame) {
+  auto fullData = readFile(pngFile);
+  auto decoder = createDecoder();
+  ASSERT_FALSE(fullData->isEmpty());
+
+  RefPtr<SharedBuffer> partialData =
+      SharedBuffer::create(fullData->data(), offsetMidFirstFrame);
+  decoder->setData(partialData, false);
+
+  EXPECT_EQ(1u, decoder->frameCount());
+  ImageFrame* frame = decoder->frameBufferAtIndex(0);
+  EXPECT_EQ(frame->getStatus(), ImageFrame::FramePartial);
+  unsigned hashPartial = hashBitmap(frame->bitmap());
+
+  decoder->setData(fullData.get(), true);
+  frame = decoder->frameBufferAtIndex(0);
+  EXPECT_EQ(frame->getStatus(), ImageFrame::FrameComplete);
+  unsigned hashFull = hashBitmap(frame->bitmap());
+
+  EXPECT_FALSE(decoder->failed());
+  EXPECT_NE(hashFull, hashPartial);

[scroggo_chromium, 2016/12/05 14:40:17]

It might be more interesting to verify that hashFull equals the hash of decoding
when all the data is provided up front.

[joostouwerling, 2016/12/05 18:29:32]

Done.

+}
+
+// This test verifies that the frame buffer contents change when progressively
+// decoding the first frame. It should change more than one time: once for the
+// first data, and at least once more thereafter. If |offsetFirstFrameEnd| == 0,
+// the test uses the full data size of the image for progressive decoding.
+void testProgressiveDecodingChangesFrameBuffer(const char* pngFile,

[scroggo_chromium, 2016/12/05 14:40:17]

This seems like a similar test to the one above. Do we need two separate tests?

[joostouwerling, 2016/12/05 18:29:32]

They're somewhat similar, but especially with the new changes, I'd opt to keep
it there. It now verifies that the frame bitmap changes for every row, which is
what you'd expect when decoding it pixel by pixel.

+                                               size_t offsetFirstFrameEnd,
+                                               size_t step = 1u) {
+  auto fullData = readFile(pngFile);
+  auto decoder = createDecoder();
+  ASSERT_FALSE(fullData->isEmpty());
+
+  if (offsetFirstFrameEnd == 0)
+    offsetFirstFrameEnd = fullData->size();
+
+  size_t numTimesBufferChanged = 0;
+  unsigned lastHash;
+
+  for (size_t length = 1; length <= offsetFirstFrameEnd; length += step) {
+    RefPtr<SharedBuffer> data = SharedBuffer::create(fullData->data(), length);
+    decoder->setData(data, false);
+    ImageFrame* frame = decoder->frameBufferAtIndex(0);
+    if (!frame)
+      continue;
+    unsigned newHash = hashBitmap(frame->bitmap());
+    if (newHash != lastHash) {

[scroggo_chromium, 2016/12/05 14:40:17]

The first time through the loop, lastHash will be uninitialized.

[joostouwerling, 2016/12/05 18:29:32]

Done.

+      lastHash = newHash;
+      numTimesBufferChanged++;

[scroggo_chromium, 2016/12/05 14:40:17]

After we hit this the second time, do we really need to keep running the test?
We will not do any checks that will turn out differently after that.

[joostouwerling, 2016/12/05 18:29:32]

I changed it to check whether it changes for every row.

+    }
+  }
+  EXPECT_GT(numTimesBufferChanged, 1u);
+}
+
+// Modify the frame data bytes for frame |frameIndex| so that decoding fails.
+// Parsing should work fine, and is checked with |expectedFrameCountBefore|. If
+// the failure should invalidate the decoder, |expectFailure| should be set to
+// true. If not, |expectedFrameCountAfter| should indicate the new frame count
+// after the failure.
+void testFailureDuringDecode(const char* file,
+                             size_t idatOffset,
+                             size_t frameIndex,
+                             bool expectFailure,
+                             size_t expectedFrameCountBefore,
+                             size_t expectedFrameCountAfter = 0u) {
+  RefPtr<SharedBuffer> fullData = readFile(file);
+  ASSERT_FALSE(fullData->isEmpty());
+
+  // This is the offset where the frame data chunk frame |frameIndex| starts.
+  RefPtr<SharedBuffer> data =
+      SharedBuffer::create(fullData->data(), idatOffset + 8u);
+  // Repeat the first 8 bytes of the frame data. This should result in a
+  // successful parse, since frame data is not analyzed in that step, but
+  // should give an error during decoding.
+  data->append(fullData->data() + idatOffset, 8u);
+  data->append(fullData->data() + idatOffset + 16u,
+               fullData->size() - idatOffset - 16u);
+
+  auto decoder = createDecoder();
+  decoder->setData(data.get(), true);
+
+  EXPECT_EQ(expectedFrameCountBefore, decoder->frameCount());
+
+  const ImageFrame* const frame = decoder->frameBufferAtIndex(frameIndex);
+  EXPECT_EQ(expectFailure, decoder->failed());
+  if (!expectFailure) {
+    EXPECT_EQ(expectedFrameCountAfter, decoder->frameCount());
+    EXPECT_EQ(ImageFrame::FrameEmpty, frame->getStatus());
+  }
+}
+
+}  // Anonymous namespace
+
+// Static PNG tests
+
+TEST(StaticPNGTests, repetitionCountTest) {
+  testRepetitionCount("/LayoutTests/images/resources/png-simple.png",
+                      cAnimationNone);
+}
+
+TEST(StaticPNGTests, sizeTest) {
+  testSize("/LayoutTests/images/resources/png-simple.png", IntSize(111, 29));
+}
+
+TEST(StaticPNGTests, MetaDataTest) {
+  const size_t expectedFrameCount = 1;
+  const size_t expectedDuration = 0;
+  auto decoder =
+      createDecoderWithPngData("/LayoutTests/images/resources/png-simple.png");
+  EXPECT_EQ(expectedFrameCount, decoder->frameCount());
+  EXPECT_EQ(expectedDuration, decoder->frameDurationAtIndex(0));
+}
+
+TEST(StaticPNGTests, ProgressiveDecoding) {
+  testProgressiveDecoding(&createDecoder,
+                          "/LayoutTests/images/resources/png-simple.png", 11u);
+}
+
+TEST(StaticPNGTests, ProgressiveDecodingChangesFrameBuffer) {
+  testProgressiveDecodingChangesFrameBuffer(
+      "/LayoutTests/images/resources/png-simple.png", 0u, 5u);
+}
+
+TEST(StaticPNGTests, ProgressiveDecodingContinuesAfterFullData) {
+  testProgressiveDecodingContinuesAfterFullData(
+      "/LayoutTests/images/resources/png-simple.png", 1000u);
+}
+
+TEST(StaticPNGTests, FailureDuringDecodingInvalidatesDecoder) {
+  testFailureDuringDecode(
+      "/LayoutTests/images/resources/png-simple.png",
+      85u,   // idat offset for frame index 0
+      0u,    // try to decode frame index 0
+      true,  // expect the decoder to be invalidated after the failure
+      1u);   // expected frame count before failure
+}
+
+// For static images, frameIsCompleteAtIndex(0) should return true if and only
+// if the frame is successfully decoded, not when it is fully received.
+TEST(StaticPNGTests, VerifyFrameCompleteBehavior) {
+  auto decoder =
+      createDecoderWithPngData("/LayoutTests/images/resources/png-simple.png");
+  EXPECT_EQ(1u, decoder->frameCount());
+  EXPECT_FALSE(decoder->frameIsCompleteAtIndex(0));
+  EXPECT_EQ(ImageFrame::FrameComplete,
+            decoder->frameBufferAtIndex(0)->getStatus());
+  EXPECT_TRUE(decoder->frameIsCompleteAtIndex(0));
+}
+
+};  // namespace blink