Avoid dereferencing find() without checking for == end()

media/base/audio_video_metadata_extractor_unittest.cc

 // Copyright 2014 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 "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/sha1.h"
 #include "build/build_config.h"
 #include "media/base/audio_video_metadata_extractor.h"
 #include "media/base/test_data_util.h"
@@ skipping 43 matching lines @@
   EXPECT_EQ(0u, extractor->stream_infos()[0].tags.size());
 
   EXPECT_EQ(1u, extractor->stream_infos()[1].tags.size());
   EXPECT_EQ("vorbis", extractor->stream_infos()[1].type);
   EXPECT_EQ("Processed by SoX",
             extractor->stream_infos()[1].tags.find("COMMENT")->second);
 
   EXPECT_EQ(0u, extractor->attached_images_bytes().size());
 }
 
+const std::string GetTagValue(
+    const media::AudioVideoMetadataExtractor::TagDictionary& tags,
+    const char* tag_name) {
+  auto tag_data = tags.find(tag_name);
+  EXPECT_NE(tag_data, tags.end());

[DaleCurtis, 2016/01/28 21:54:47]

I'd just drop this since it's just noise in the test log if it fails here (vs on
the actual test line below) and use a ternary for style.

[brucedawson, 2016/01/28 22:17:26]

Sounds good.

The original advice was to use ASSERT, but that does a return; and therefore
cannot be used from a helper function such as this.

+  if (tag_data == tags.end())
+    return "";
+  return tag_data->second;
+}
+
 TEST(AudioVideoMetadataExtractorTest, AudioWAV) {
   scoped_ptr<AudioVideoMetadataExtractor> extractor =
       GetExtractor("sfx_u8.wav", true, true, 0, -1, -1);
   EXPECT_EQ("Lavf54.37.100", extractor->encoder());
   EXPECT_EQ("Amadeus Pro", extractor->encoded_by());
 
   EXPECT_EQ("wav", extractor->stream_infos()[0].type);
   EXPECT_EQ(2u, extractor->stream_infos().size());
 
   EXPECT_EQ(2u, extractor->stream_infos()[0].tags.size());
   EXPECT_EQ("Lavf54.37.100",
-            extractor->stream_infos()[0].tags.find("encoder")->second);
+            GetTagValue(extractor->stream_infos()[0].tags, "encoder"));
   EXPECT_EQ("Amadeus Pro",
-            extractor->stream_infos()[0].tags.find("encoded_by")->second);
+            GetTagValue(extractor->stream_infos()[0].tags, "encoded_by"));
 
   EXPECT_EQ("pcm_u8", extractor->stream_infos()[1].type);
   EXPECT_EQ(0u, extractor->stream_infos()[1].tags.size());
 
   EXPECT_EQ(0u, extractor->attached_images_bytes().size());
 }
 
 TEST(AudioVideoMetadataExtractorTest, VideoWebM) {
   scoped_ptr<AudioVideoMetadataExtractor> extractor =
       GetExtractor("bear-320x240-multitrack.webm", true, true, 2, 320, 240);
@@ skipping 110 matching lines @@
             extractor->attached_images_bytes()[0].substr(0, 8));
   EXPECT_EQ("IEND\xae\x42\x60\x82",
             extractor->attached_images_bytes()[0].substr(
                 extractor->attached_images_bytes()[0].size() - 8, 8));
   EXPECT_EQ("\xF3\xED\x8F\xC7\xC7\x98\xB9V|p\xC0u!\xB5\x82\xCF\x95\xF0\xCD\xCE",
             base::SHA1HashString(extractor->attached_images_bytes()[0]));
 }
 #endif
 
 }  // namespace media