Sync: Print FakeServer contents on test failure

sync/test/fake_server/fake_server_verifier.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 "sync/test/fake_server/fake_server_verifier.h"
 
+#include "base/json/json_writer.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/values.h"
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/test/fake_server/fake_server.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+using base::JSONWriter;

[maniscalco, 2015/03/18 15:33:55]

Is the using statement necessary?  I ask because it look like you're using the
JSONWriter:: namespace prefix below.

[pval...(no longer on Chromium), 2015/03/23 23:35:39]

It's not necessary, but I think the code below reads better (and fits decently
in 80 chars) without the base:: prefix. 

 using std::string;
 using testing::AssertionFailure;
 using testing::AssertionResult;
 using testing::AssertionSuccess;
 
 namespace {
 
 AssertionResult DictionaryCreationAssertionFailure() {
   return AssertionFailure() << "FakeServer failed to create an entities "
                             << "dictionary.";
 }
 
 AssertionResult VerificationCountAssertionFailure(size_t actual_count,
                                                   size_t expected_count) {
   return AssertionFailure() << "Actual count: " << actual_count << "; "
                             << "Expected count: " << expected_count;
 }
 
 AssertionResult UnknownTypeAssertionFailure(const string& model_type) {
   return AssertionFailure() << "Verification not attempted. Unknown ModelType: "
                             << model_type;
 }
 
+// Caller maintains ownership of |entities|.
+string ConvertFakeServerContentsToString(base::DictionaryValue* entities) {

[maniscalco, 2015/03/18 15:33:56]

Does entities need to be a non-const pointer?  Could you pass by const ref
instead?  That way the caller knows there's no way this function will modify
entities.

[pval...(no longer on Chromium), 2015/03/23 23:35:39]

It does not. Thanks for pointing this out; I've made the change and really like
how this looks now.

[maniscalco, 2015/03/24 00:11:19]

Great.

+  string entities_str;
+  if (!JSONWriter::WriteWithOptions(entities,
+                                    JSONWriter::OPTIONS_PRETTY_PRINT,
+                                    &entities_str)) {
+    entities_str = "Could not convert FakeServer contents to string.";
+  }
+  return "FakeServer contents:\n" + entities_str;
+}
+
 }  // namespace
 
 namespace fake_server {
 
 FakeServerVerifier::FakeServerVerifier(FakeServer* fake_server)
     : fake_server_(fake_server) { }
 
 FakeServerVerifier::~FakeServerVerifier() {}
 
 AssertionResult FakeServerVerifier::VerifyEntityCountByType(
     size_t expected_count,
     syncer::ModelType model_type) const {
   scoped_ptr<base::DictionaryValue> entities =
       fake_server_->GetEntitiesAsDictionaryValue();
   if (!entities.get()) {
     return DictionaryCreationAssertionFailure();
   }
 
   string model_type_string = ModelTypeToString(model_type);
   base::ListValue* entity_list = NULL;
   if (!entities->GetList(model_type_string, &entity_list)) {
     return UnknownTypeAssertionFailure(model_type_string);
   } else if  (expected_count != entity_list->GetSize()) {
     return VerificationCountAssertionFailure(entity_list->GetSize(),
-                                             expected_count);
+                                             expected_count)
+        << "\n\n"
+        << ConvertFakeServerContentsToString(entities.get());
   }
 
   return AssertionSuccess();
 }
 
 AssertionResult FakeServerVerifier::VerifyEntityCountByTypeAndName(
     size_t expected_count,
     syncer::ModelType model_type,
     const string& name) const {
   scoped_ptr<base::DictionaryValue> entities =
@@ skipping 12 matching lines @@
       if (name_value->Equals(*it)) {
         actual_count++;
       }
     }
   }
 
   if (!entity_list) {
     return UnknownTypeAssertionFailure(model_type_string);
   } else if (actual_count != expected_count) {
     return VerificationCountAssertionFailure(actual_count, expected_count)
-        << "; Name: " << name;
+        << "; Name: "
+        << name
+        << "\n\n"
+        << ConvertFakeServerContentsToString(entities.get());
   }
 
   return AssertionSuccess();
 }
 
 }  // namespace fake_server