formats/bmff/assessor_test.cc

// Copyright 2026 Google LLC
//
// 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
//
//    https://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 "formats/bmff/assessor.h"

#include <string>

#include "absl/status/status_matchers.h"
#include "absl/strings/str_cat.h"
#include "formats/bmff/test_utils.h"
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "riegeli/bytes/string_reader.h"

namespace credentio {
namespace {

using ::absl_testing::IsOkAndHolds;

TEST(IsSupportedTest, FailsForTooFewBytes) {
  std::string image = "a";
  riegeli::StringReader<> input(image);
  EXPECT_THAT(BmffAssessor().IsSupported(input), IsOkAndHolds(false));
}

TEST(IsSupportedTest, FailsForNotStartingWithFtyp) {
  std::string image = "this_is_not_a_bmff";
  riegeli::StringReader<> input(image);
  EXPECT_THAT(BmffAssessor().IsSupported(input), IsOkAndHolds(false));
}

TEST(IsSupportedTest, ValidStartingFtype) {
  std::string image = credentio_testing::Box("ftyp", "heictest");
  riegeli::StringReader<> input(image);
  EXPECT_THAT(BmffAssessor().IsSupported(input), IsOkAndHolds(true));
}

TEST(IsSupportedTest, ValidStartingMoov) {
  std::string image = credentio_testing::Box("moov", "data");
  riegeli::StringReader<> input(image);
  EXPECT_THAT(BmffAssessor().IsSupported(input), IsOkAndHolds(true));
}

TEST(IsSupportedTest, UnsupportedFileType) {
  std::string image = credentio_testing::Box("ftyp", "testtest");
  riegeli::StringReader<> input(image);
  EXPECT_THAT(BmffAssessor().IsSupported(input), IsOkAndHolds(false));
}

TEST(IsSupportedTest, SupportedFileTypeWithCompatibleBrand) {
  std::string image = credentio_testing::Box("ftyp", "testtestmp42");
  riegeli::StringReader<> input(image);
  EXPECT_THAT(BmffAssessor().IsSupported(input), IsOkAndHolds(true));
}

TEST(IsSupportedTest, ValidStartingBytesAtOffset2) {
  std::string image =
      absl::StrCat("ab", credentio_testing::Box("ftyp", "heictest"));
  riegeli::StringReader<> input(image);

  // Invalid at 0
  EXPECT_THAT(BmffAssessor().IsSupported(input), IsOkAndHolds(false));
  EXPECT_EQ(input.pos(), 0);

  // Valid at 2
  ASSERT_TRUE(input.Seek(2));
  EXPECT_THAT(BmffAssessor().IsSupported(input), IsOkAndHolds(true));
  EXPECT_EQ(input.pos(), 2);
}

TEST(IsSupportedTest, StopsEarlyAfterFtyp) {
  // Supported major brand followed by invalid truncated box data.
  // Assessor should stop immediately and declare it supported, ignoring later
  // invalid data.
  std::string image = absl::StrCat(credentio_testing::Box("ftyp", "heictest"),
                                   "invalid_truncated_box_data");
  riegeli::StringReader<> input(image);
  EXPECT_THAT(BmffAssessor().IsSupported(input), IsOkAndHolds(true));
}

TEST(IsSupportedTest, StopsEarlyAfterFtypCompatibleBrand) {
  // Supported compatible brand in ftyp followed by truncated box data should be
  // supported.
  std::string image =
      absl::StrCat(credentio_testing::Box("ftyp", "testtestmp42"),
                   "invalid_truncated_box_data");
  riegeli::StringReader<> input(image);
  EXPECT_THAT(BmffAssessor().IsSupported(input), IsOkAndHolds(true));
}

TEST(IsSupportedTest, StopsEarlyOnUnsupportedFtypAndIgnoresMoov) {
  // Unsupported ftyp followed by a moov box.
  // Assessor should terminate early and return unsupported (false) since it
  // shouldn't inspect moov.
  std::string image = absl::StrCat(credentio_testing::Box("ftyp", "testtest"),
                                   credentio_testing::Box("moov", "data"));
  riegeli::StringReader<> input(image);
  EXPECT_THAT(BmffAssessor().IsSupported(input), IsOkAndHolds(false));
}

TEST(IsSupportedTest, StopsEarlyAfterMoov) {
  // Supported moov box followed by invalid truncated box data.
  // Assessor should terminate early indicating supported (true).
  std::string image = absl::StrCat(credentio_testing::Box("moov", "data"),
                                   "invalid_truncated_box_data");
  riegeli::StringReader<> input(image);
  EXPECT_THAT(BmffAssessor().IsSupported(input), IsOkAndHolds(true));
}

TEST(IsSupportedTest, FtypBoxTooSmallForBrandsDoesNotUnderflow) {
  // ftyp box size of 8 bytes followed by data containing a supported brand "qt
  // "
  std::string image =
      absl::StrCat(credentio_testing::BadBox("ftyp", "", 8), "unkn0000qt  ");
  riegeli::StringReader<> input(image);
  EXPECT_THAT(BmffAssessor().IsSupported(input), IsOkAndHolds(false));
}

}  // namespace
}  // namespace credentio