Fix CryptAuthApiCallFlow resulting in an error if the server returns an empty string.

components/proximity_auth/cryptauth/cryptauth_api_call_flow_unittest.cc

Index: components/proximity_auth/cryptauth/cryptauth_api_call_flow_unittest.cc
diff --git a/components/proximity_auth/cryptauth/cryptauth_api_call_flow_unittest.cc b/components/proximity_auth/cryptauth/cryptauth_api_call_flow_unittest.cc
index 2d1cf5cdf506dad2deb6b50575975ae321c0ffc4..53417e724249443f91fb9a51f48b800769b59723 100644
--- a/components/proximity_auth/cryptauth/cryptauth_api_call_flow_unittest.cc
+++ b/components/proximity_auth/cryptauth/cryptauth_api_call_flow_unittest.cc
@@ -102,6 +102,8 @@ class ProximityAuthCryptAuthApiCallFlowTest
   scoped_refptr<net::TestURLRequestContextGetter> url_request_context_getter_;
   scoped_ptr<net::TestURLFetcherFactory> url_fetcher_factory_;
   CryptAuthApiCallFlow flow_;
+
+  DISALLOW_COPY_AND_ASSIGN(ProximityAuthCryptAuthApiCallFlowTest);
 };
 
 TEST_F(ProximityAuthCryptAuthApiCallFlowTest, RequestSuccess) {
@@ -128,12 +130,13 @@ TEST_F(ProximityAuthCryptAuthApiCallFlowTest, RequestStatus500) {
   EXPECT_EQ("HTTP status: 500", *error_message_);
 }
 
+// The empty string is a valid protocol buffer message serialization.
 TEST_F(ProximityAuthCryptAuthApiCallFlowTest, ResponseWithNoBody) {
   StartApiCallFlow();
   CompleteCurrentRequest(
       net::URLRequestStatus::SUCCESS, net::HTTP_OK, std::string());
-  EXPECT_FALSE(result_);
-  EXPECT_EQ("No response body", *error_message_);
+  EXPECT_EQ(std::string(), *result_);
+  EXPECT_FALSE(error_message_);
 }

[Ilya Sherman, 2014/12/10 23:38:29]

Please add a new test to provide coverage for the "kResponseBodyError" case.

[Tim Song, 2014/12/11 00:12:55]

Hmm... I'm note sure how to force this error, as the URLFetcher should be
properly configured in the callback. However, I'm hesitant to change this to a
CHECK.

 
 }  // namespace proximity_auth