Bug 1790614 - Part 1: Add helpers for asserting nsresult in gtest, r=ahal

These helpers are inspired by the gtest-provided
{ASSERT,ENSURE}_HRESULT_{SUCCEEDED,FAILED} macros.

These are intended as replacements for patterns like
ENSURE_TRUE(NS_SUCCEEDED(rv)) which will actually report the encountered
nsresult error code code when they fail.

Differential Revision: https://phabricator.services.mozilla.com/D157213

testing/gtest/mozilla/MozAssertions.cpp

@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "MozAssertions.h"
+#include "mozilla/ErrorNames.h"
+#include "nsString.h"
+
+namespace mozilla::gtest {
+
+static testing::AssertionResult NsresultFailureHelper(const char* expr,
+                                                      const char* expected,
+                                                      nsresult rv) {
+  nsAutoCString name;
+  GetErrorName(rv, name);
+
+  return testing::AssertionFailure()
+         << "Expected: " << expr << " " << expected << ".\n"
+         << "  Actual: " << name << "\n";
+}
+
+testing::AssertionResult IsNsresultSuccess(const char* expr, nsresult rv) {
+  if (NS_SUCCEEDED(rv)) {
+    return testing::AssertionSuccess();
+  }
+  return NsresultFailureHelper(expr, "succeeds", rv);
+}
+
+testing::AssertionResult IsNsresultFailure(const char* expr, nsresult rv) {
+  if (NS_FAILED(rv)) {
+    return testing::AssertionSuccess();
+  }
+  return NsresultFailureHelper(expr, "failed", rv);
+}
+
+}  // namespace mozilla::gtest

testing/gtest/mozilla/MozAssertions.h

@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_gtest_MozAssertions_h__
+#define mozilla_gtest_MozAssertions_h__
+
+#include "gtest/gtest.h"
+#include "nsError.h"
+
+namespace mozilla::gtest {
+
+testing::AssertionResult IsNsresultSuccess(const char* expr, nsresult rv);
+testing::AssertionResult IsNsresultFailure(const char* expr, nsresult rv);
+
+}  // namespace mozilla::gtest
+
+#define EXPECT_NS_SUCCEEDED(expr) \
+  EXPECT_PRED_FORMAT1(::mozilla::gtest::IsNsresultSuccess, (expr))
+
+#define ASSERT_NS_SUCCEEDED(expr) \
+  ASSERT_PRED_FORMAT1(::mozilla::gtest::IsNsresultSuccess, (expr))
+
+#define EXPECT_NS_FAILED(expr) \
+  EXPECT_PRED_FORMAT1(::mozilla::gtest::IsNsresultFailure, (expr))
+
+#define ASSERT_NS_FAILED(expr) \
+  ASSERT_PRED_FORMAT1(::mozilla::gtest::IsNsresultFailure, (expr))
+
+#endif  // mozilla_gtest_MozAssertions_h__

testing/gtest/mozilla/moz.build

@@ -17,8 +17,13 @@ if CONFIG["ENABLE_TESTS"]:
         "gmock-custom/gmock-port.h",
     ]
 
+    EXPORTS.mozilla.gtest += [
+        "MozAssertions.h",
+    ]
+
     SOURCES += [
         "GTestRunner.cpp",
+        "MozAssertions.cpp",
         "MozGTestBench.cpp",
         "SanityTest.cpp",
     ]