--- a/media/libstagefright/gtest/TestMP4Rust.cpp
+++ b/media/libstagefright/gtest/TestMP4Rust.cpp
@@ -17,37 +17,37 @@ using namespace mozilla;
 TEST(rust, MP4MetadataEmpty)
 {
   int32_t rv;
 
   mp4parse_state* context = mp4parse_new();
   ASSERT_NE(context, nullptr);
 
   rv = mp4parse_read(nullptr, nullptr, 0);
-  EXPECT_EQ(rv, -1);
+  EXPECT_EQ(rv, MP4PARSE_ERROR_BADARG);
   rv = mp4parse_read(context, nullptr, 0);
-  EXPECT_EQ(rv, -1);
+  EXPECT_EQ(rv, MP4PARSE_ERROR_BADARG);
 
   size_t len = 4097;
   rv = mp4parse_read(nullptr, nullptr, len);
-  EXPECT_EQ(rv, -1);
+  EXPECT_EQ(rv, MP4PARSE_ERROR_BADARG);
   rv = mp4parse_read(context, nullptr, len);
-  EXPECT_EQ(rv, -1);
+  EXPECT_EQ(rv, MP4PARSE_ERROR_BADARG);
 
   std::vector<uint8_t> buf;
   rv = mp4parse_read(nullptr, buf.data(), buf.size());
-  EXPECT_EQ(rv, -1);
+  EXPECT_EQ(rv, MP4PARSE_ERROR_BADARG);
   rv = mp4parse_read(context, buf.data(), buf.size());
-  EXPECT_EQ(rv, -1);
+  EXPECT_EQ(rv, MP4PARSE_ERROR_BADARG);
 
   buf.reserve(len);
   rv = mp4parse_read(nullptr, buf.data(), buf.size());
-  EXPECT_EQ(rv, -1);
+  EXPECT_EQ(rv, MP4PARSE_ERROR_BADARG);
   rv = mp4parse_read(context, buf.data(), buf.size());
-  EXPECT_EQ(rv, -1);
+  EXPECT_EQ(rv, MP4PARSE_ERROR_BADARG);
 
   mp4parse_free(context);
 }
 
 TEST(rust, MP4Metadata)
 {
   FILE* f = fopen("street.mp4", "rb");
   ASSERT_TRUE(f != nullptr);
@@ -57,12 +57,15 @@ TEST(rust, MP4Metadata)
   size_t read = fread(buf.data(), sizeof(decltype(buf)::value_type), buf.size(), f);
   buf.resize(read);
   fclose(f);
 
   mp4parse_state* context = mp4parse_new();
   ASSERT_NE(context, nullptr);
 
   int32_t rv = mp4parse_read(context, buf.data(), buf.size());
-  EXPECT_EQ(rv, 2);
+  EXPECT_EQ(rv, MP4PARSE_OK);
+
+  uint32_t tracks = mp4parse_get_track_count(context);
+  EXPECT_EQ(tracks, 2U);
 
   mp4parse_free(context);
 }