Output to the test warning file if no tests are linked.

Bazel sets the environment variable TEST_WARNINGS_OUTPUT_FILE
https://bazel.build/reference/test-encyclopedia#initial-conditions

If no tests are linked and the new flag --gtest_fail_if_no_test_linked
is not true (which is the current default), we can still warn the user
as this may be a programming error without failing the test (which would
break existing users).

PiperOrigin-RevId: 731402363
Change-Id: Ia481689efd4bd18889feaaa38bc56049a3f651cd

1 files changed, 41 insertions, 5 deletions

diff --git a/googletest/src/gtest.cc b/googletest/src/gtest.cc
index 81096ae..26959df 100644
--- a/googletest/src/gtest.cc
+++ b/googletest/src/gtest.cc
@@ -192,12 +192,17 @@ static const char kDefaultOutputFormat[] = "xml";
 // The default output file.
 static const char kDefaultOutputFile[] = "test_detail";
 
+// These environment variables are set by Bazel.
+// https://bazel.build/reference/test-encyclopedia#initial-conditions
+//
 // The environment variable name for the test shard index.
 static const char kTestShardIndex[] = "GTEST_SHARD_INDEX";
 // The environment variable name for the total number of test shards.
 static const char kTestTotalShards[] = "GTEST_TOTAL_SHARDS";
 // The environment variable name for the test shard status file.
 static const char kTestShardStatusFile[] = "GTEST_SHARD_STATUS_FILE";
+// The environment variable name for the test output warnings file.
+static const char kTestWarningsOutputFile[] = "TEST_WARNINGS_OUTPUT_FILE";
 
 namespace internal {
 
@@ -5875,6 +5880,23 @@ TestSuite* UnitTestImpl::GetTestSuite(
 static void SetUpEnvironment(Environment* env) { env->SetUp(); }
 static void TearDownEnvironment(Environment* env) { env->TearDown(); }
 
+// If the environment variable TEST_WARNINGS_OUTPUT_FILE was provided, appends
+// `str` to the file, creating the file if necessary.
+#if GTEST_HAS_FILE_SYSTEM
+static void AppendToTestWarningsOutputFile(const std::string& str) {
+  const char* const filename = posix::GetEnv(kTestWarningsOutputFile);
+  if (filename == nullptr) {
+    return;
+  }
+  auto* const file = posix::FOpen(filename, "a");
+  if (file == nullptr) {
+    return;
+  }
+  GTEST_CHECK_(fwrite(str.data(), 1, str.size(), file) == str.size());
+  GTEST_CHECK_(posix::FClose(file) == 0);
+}
+#endif  // GTEST_HAS_FILE_SYSTEM
+
 // Runs all tests in this UnitTest object, prints the result, and
 // returns true if all tests are successful.  If any exception is
 // thrown during a test, the test is considered to be failed, but the
@@ -5896,12 +5918,26 @@ bool UnitTestImpl::RunAllTests() {
   // user didn't call InitGoogleTest.
   PostFlagParsingInit();
 
-  if (GTEST_FLAG_GET(fail_if_no_test_linked) && total_test_count() == 0) {
+  // Handle the case where the program has no tests linked.
+  // Sometimes this is a programmer mistake, but sometimes it is intended.
+  if (total_test_count() == 0) {
+    constexpr char kNoTestLinkedMessage[] =
+        "This test program does NOT link in any test case.";
+    constexpr char kNoTestLinkedFatal[] =
+        "This is INVALID. Please make sure to link in at least one test case.";
+    constexpr char kNoTestLinkedWarning[] =
+        "Please make sure this is intended.";
+    const bool fail_if_no_test_linked = GTEST_FLAG_GET(fail_if_no_test_linked);
     ColoredPrintf(
-        GTestColor::kRed,
-        "This test program does NOT link in any test case. This is INVALID. "
-        "Please make sure to link in at least one test case.\n");
-    return false;
+        GTestColor::kRed, "%s %s\n", kNoTestLinkedMessage,
+        fail_if_no_test_linked ? kNoTestLinkedFatal : kNoTestLinkedWarning);
+    if (fail_if_no_test_linked) {
+      return false;
+    }
+#if GTEST_HAS_FILE_SYSTEM
+    AppendToTestWarningsOutputFile(std::string(kNoTestLinkedMessage) + ' ' +
+                                   kNoTestLinkedWarning + '\n');
+#endif  // GTEST_HAS_FILE_SYSTEM
   }
 
 #if GTEST_HAS_FILE_SYSTEM