Bug 1175322 - Add gtests for rust mp4 metadata parser. r=k17e

Add a null buffer test.
Add a street.mp4 test.

We have trouble parsing gizmo.mp4, and the dom/media/gtest
already exposes the file, which is confusing since we apparently
can't have duplicates in TEST_HARNESS_FILES.

The street.mp4 test always fails because we don't catch
the eof in the rust code.

media/libstagefright/gtest/TestMP4Rust.cpp

@@ -0,0 +1,48 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "gtest/gtest.h"
+#include "mp4_demuxer/MP4Metadata.h"
+
+#include <cstdint>
+#include <fstream>
+#include <vector>
+
+extern "C" bool read_box_from_buffer(uint8_t *buffer, size_t size);
+
+using namespace mp4_demuxer;
+using namespace mozilla;
+
+TEST(rust, MP4MetadataEmpty)
+{
+  bool rv;
+  rv = read_box_from_buffer(nullptr, 0);
+  EXPECT_EQ(rv, false);
+
+  size_t len = 4097;
+  rv = read_box_from_buffer(nullptr, len);
+  EXPECT_EQ(rv, false);
+
+  std::vector<uint8_t> buf;
+  rv = read_box_from_buffer(buf.data(), buf.size());
+  EXPECT_EQ(rv, false);
+
+  buf.reserve(len);
+  rv = read_box_from_buffer(buf.data(), buf.size());
+  EXPECT_EQ(rv, false);
+}
+
+TEST(rust, MP4Metadata)
+{
+  std::ifstream f("street.mp4");
+  ASSERT_TRUE(f.is_open());
+
+  size_t len = 4096;
+  std::vector<uint8_t> buf;
+  buf.reserve(len);
+  f.read(reinterpret_cast<char*>(buf.data()), buf.size());
+  bool rv = read_box_from_buffer(buf.data(), buf.size());
+  ASSERT_FALSE(rv); // Expected fail: need to trap eof.
+}

media/libstagefright/gtest/moz.build

@@ -10,6 +10,12 @@ SOURCES += [
     'TestInterval.cpp',
 ]
 
+if CONFIG['MOZ_RUST']:
+    UNIFIED_SOURCES += ['TestMP4Rust.cpp',]
+    TEST_HARNESS_FILES.gtest += [
+        '../../../dom/media/test/street.mp4',
+    ]
+
 FINAL_LIBRARY = 'xul-gtest'
 
 FAIL_ON_WARNINGS = True