Define canonical enum for "HeliumResult" status values.

Add HeliumResult-to-string mapping for easier logging.
Add unit tests for string conversion functions.

R=lethalantidote@chromium.org,gcasto@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2385913002
Cr-Commit-Position: refs/heads/master@{#422683}

blimp/net/BUILD.gn

@@ -94,6 +94,9 @@ component("net") {
 
 source_set("helium") {
   sources = [
+    "helium/helium_errors.h",
+    "helium/helium_result.cc",
+    "helium/helium_result.h",
     "helium/vector_clock.cc",
     "helium/vector_clock.h",
   ]
@@ -110,7 +113,7 @@ source_set("helium") {
 
 source_set("net_export") {
   sources = [
-      "blimp_net_export.h",
+    "blimp_net_export.h",
   ]
 }
 
@@ -159,6 +162,7 @@ source_set("unit_tests") {
     "delta_encoding_unittest.cc",
     "engine_authentication_handler_unittest.cc",
     "engine_connection_manager_unittest.cc",
+    "helium/helium_result_unittest.cc",
     "helium/vector_clock_unittest.cc",
     "input_message_unittest.cc",
     "ssl_client_transport_unittest.cc",

blimp/net/helium/helium_errors.h

+// Copyright 2016 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.
+
+// This file intentionally does not have header guards, it's included
+// inside a macro to generate enum values.
+
+// This file contains the list of Helium error codes.
+
+HELIUM_ERROR(INTERNAL_ERROR, 1)
+
+// The operation could not be performed because the connection to the peer was
+// lost.
+HELIUM_ERROR(DISCONNECTED, 2)

blimp/net/helium/helium_result.cc

+// Copyright 2016 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 "blimp/net/helium/helium_result.h"
+
+#include "base/logging.h"
+
+namespace blimp {
+
+const char* HeliumResultToString(HeliumResult result) {
+  switch (result) {
+    case HeliumResult::SUCCESS:
+      return "SUCCESS";
+      break;
+#define HELIUM_ERROR(label, value) \
+  case HeliumResult::ERR_##label:  \
+    return "ERR_" #label;
+      break;
+#include "blimp/net/helium/helium_errors.h"
+#undef HELIUM_ERROR
+  }
+
+  NOTREACHED();
+  return "";
+}
+
+}  // namespace blimp

blimp/net/helium/helium_result.h

+// Copyright 2016 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.
+
+#ifndef BLIMP_NET_HELIUM_HELIUM_RESULT_H_
+#define BLIMP_NET_HELIUM_HELIUM_RESULT_H_
+
+#include "blimp/net/blimp_net_export.h"
+
+namespace blimp {
+
+// Defines the canonical list of Helium result codes.
+// HeliumResult::OK is the only non-error code.
+// All other codes are considered errors and are prefixed by ERR_.
+// See error_list.h for the unprefixed list of error codes.
+//
+// (Approach is inspired by net/base/net_errors.h)
+enum HeliumResult {
+  SUCCESS,
+#define HELIUM_ERROR(label, value) ERR_##label = value,
+#include "blimp/net/helium/helium_errors.h"
+#undef HELIUM_ERROR
+};
+
+// Gets a human-readable string representation of |result|.
+const char* BLIMP_NET_EXPORT HeliumResultToString(HeliumResult result);
+
+}  // namespace blimp
+
+#endif  // BLIMP_NET_HELIUM_HELIUM_RESULT_H_

blimp/net/helium/helium_result_unittest.cc

+// Copyright 2016 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 "blimp/net/helium/helium_result.h"
+
+#include "base/macros.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace blimp {
+namespace {
+
+class HeliumResultTest : public testing::Test {
+ public:
+  HeliumResultTest() {}
+  ~HeliumResultTest() override {}
+};
+
+TEST_F(HeliumResultTest, HeliumResultToString) {
+  // The exhaustive list of errors need not be specified here, but enough are
+  // specified that we can verify that the switch/case mapping works as
+  // intended.
+  EXPECT_STREQ("SUCCESS", HeliumResultToString(HeliumResult::SUCCESS));
+  EXPECT_STREQ("ERR_INTERNAL_ERROR",
+               HeliumResultToString(HeliumResult::ERR_INTERNAL_ERROR));
+  EXPECT_STREQ("ERR_DISCONNECTED",
+               HeliumResultToString(HeliumResult::ERR_DISCONNECTED));
+}
+
+}  // namespace
+}  // namespace blimp