1 files changed, 85 insertions, 0 deletions
diff --git a/src/scan_test.cc b/src/scan_test.cc
new file mode 100644
index 0000000..065ca03
--- /dev/null
+++ b/src/scan_test.cc
@@ -0,0 +1,85 @@
+// Copyright 2021 The libgav1 Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <algorithm>
+#include <cstdint>
+#include <tuple>
+#include <vector>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "src/utils/common.h"
+#include "src/utils/constants.h"
+
+namespace libgav1 {
+namespace {
+
+// Import all the constants in the anonymous namespace.
+#include "src/scan_tables.inc"
+
+class ScanOrderTest
+    : public testing::TestWithParam<std::tuple<TransformClass, TransformSize>> {
+ public:
+  ScanOrderTest() = default;
+  ScanOrderTest(const ScanOrderTest&) = delete;
+  ScanOrderTest& operator=(const ScanOrderTest&) = delete;
+  ~ScanOrderTest() override = default;
+
+ protected:
+  TransformClass tx_class_ = std::get<0>(GetParam());
+  TransformSize tx_size_ = std::get<1>(GetParam());
+};
+
+TEST_P(ScanOrderTest, AllIndicesAreScannedExactlyOnce) {
+  const int tx_width = kTransformWidth[tx_size_];
+  const int tx_height = kTransformHeight[tx_size_];
+  int num_indices;
+  if (tx_class_ == kTransformClass2D || std::max(tx_width, tx_height) == 64) {
+    const int clamped_tx_width = std::min(32, tx_width);
+    const int clamped_tx_height = std::min(32, tx_height);
+    num_indices = clamped_tx_width * clamped_tx_height;
+  } else {
+    num_indices =
+        (std::max(tx_width, tx_height) > 16) ? 64 : tx_width * tx_height;
+  }
+  const uint16_t* const scan = kScan[tx_class_][tx_size_];
+  ASSERT_NE(scan, nullptr);
+  // Ensure that all the indices are scanned exactly once.
+  std::vector<int> scanned;
+  scanned.resize(num_indices);
+  for (int i = 0; i < num_indices; ++i) {
+    scanned[scan[i]]++;
+  }
+  EXPECT_THAT(scanned, testing::Each(1));
+}
+
+constexpr TransformClass kTestTransformClasses[] = {
+    kTransformClass2D, kTransformClassVertical, kTransformClassHorizontal};
+
+constexpr TransformSize kTestTransformSizes[] = {
+    kTransformSize4x4,   kTransformSize4x8,   kTransformSize4x16,
+    kTransformSize8x4,   kTransformSize8x8,   kTransformSize8x16,
+    kTransformSize8x32,  kTransformSize16x4,  kTransformSize16x8,
+    kTransformSize16x16, kTransformSize16x32, kTransformSize16x64,
+    kTransformSize32x8,  kTransformSize32x16, kTransformSize32x32,
+    kTransformSize32x64, kTransformSize64x16, kTransformSize64x32,
+    kTransformSize64x64};
+
+INSTANTIATE_TEST_SUITE_P(
+    C, ScanOrderTest,
+    testing::Combine(testing::ValuesIn(kTestTransformClasses),
+                     testing::ValuesIn(kTestTransformSizes)));
+
+}  // namespace
+}  // namespace libgav1