Adds support for a --gtest_fail_if_no_test_linked flag

to fail the test program if no test case is linked in
(a common programmer mistake).

PiperOrigin-RevId: 730571311
Change-Id: I1dab04adfe35581274d0b4ec79a017014d50e1ea

docs/advanced.md

@@ -1929,6 +1929,20 @@ the `--gtest_also_run_disabled_tests` flag or set the
 You can combine this with the `--gtest_filter` flag to further select which
 disabled tests to run.
 
+### Enforcing Having At Least One Test Case
+
+A not uncommon programmer mistake is to write a test program that has no test
+case linked in. This can happen, for example, when you put test case definitions
+in a library and the library is not marked as "always link".
+
+To catch such mistakes, run the test program with the
+`--gtest_fail_if_no_test_linked` flag or set the `GTEST_FAIL_IF_NO_TEST_LINKED`
+environment variable to a value other than `0`. Now the program will fail if no
+test case is linked in.
+
+Note that *any* test case linked in makes the program valid for the purpose of
+this check. In particular, even a disabled test case suffices.
+
 ### Repeating the Tests
 
 Once in a while you'll run into a test whose result is hit-or-miss. Perhaps it

googletest/src/gtest.cc

@@ -258,6 +258,12 @@ GTEST_DEFINE_bool_(
                                         testing::GetDefaultFailFast()),
     "True if and only if a test failure should stop further test execution.");
 
+GTEST_DEFINE_bool_(
+    fail_if_no_test_linked,
+    testing::internal::BoolFromGTestEnv("fail_if_no_test_linked", false),
+    "True if and only if the test should fail if no test case (including "
+    "disabled test cases) is linked.");
+
 GTEST_DEFINE_bool_(
     also_run_disabled_tests,
     testing::internal::BoolFromGTestEnv("also_run_disabled_tests", false),
@@ -5890,6 +5896,14 @@ bool UnitTestImpl::RunAllTests() {
   // user didn't call InitGoogleTest.
   PostFlagParsingInit();
 
+  if (GTEST_FLAG_GET(fail_if_no_test_linked) && total_test_count() == 0) {
+    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;
+  }
+
 #if GTEST_HAS_FILE_SYSTEM
   // Even if sharding is not on, test runners may want to use the
   // GTEST_SHARD_STATUS_FILE to query whether the test supports the sharding
@@ -6677,6 +6691,7 @@ static bool ParseGoogleTestFlag(const char* const arg) {
   GTEST_INTERNAL_PARSE_FLAG(death_test_style);
   GTEST_INTERNAL_PARSE_FLAG(death_test_use_fork);
   GTEST_INTERNAL_PARSE_FLAG(fail_fast);
+  GTEST_INTERNAL_PARSE_FLAG(fail_if_no_test_linked);
   GTEST_INTERNAL_PARSE_FLAG(filter);
   GTEST_INTERNAL_PARSE_FLAG(internal_run_death_test);
   GTEST_INTERNAL_PARSE_FLAG(list_tests);

googletest/test/BUILD.bazel

@@ -47,33 +47,36 @@ cc_test(
             "*.h",
         ],
         exclude = [
-            "gtest-unittest-api_test.cc",
+            # go/keep-sorted start
-            "googletest/src/gtest-all.cc",
+            "googletest-break-on-failure-unittest_.cc",
-            "gtest_all_test.cc",
-            "gtest-death-test_ex_test.cc",
-            "gtest-listener_test.cc",
-            "gtest-unittest-api_test.cc",
-            "googletest-param-test-test.cc",
-            "googletest-param-test2-test.cc",
             "googletest-catch-exceptions-test_.cc",
             "googletest-color-test_.cc",
+            "googletest-death-test_ex_test.cc",
             "googletest-env-var-test_.cc",
+            "googletest-fail-if-no-test-linked-test-with-disabled-test_.cc",
+            "googletest-fail-if-no-test-linked-test-with-enabled-test_.cc",
             "googletest-failfast-unittest_.cc",
             "googletest-filter-unittest_.cc",
             "googletest-global-environment-unittest_.cc",
-            "googletest-break-on-failure-unittest_.cc",
+            "googletest-list-tests-unittest_.cc",
             "googletest-listener-test.cc",
             "googletest-message-test.cc",
             "googletest-output-test_.cc",
-            "googletest-list-tests-unittest_.cc",
-            "googletest-shuffle-test_.cc",
-            "googletest-setuptestsuite-test_.cc",
-            "googletest-uninitialized-test_.cc",
-            "googletest-death-test_ex_test.cc",
-            "googletest-param-test-test",
-            "googletest-throw-on-failure-test_.cc",
             "googletest-param-test-invalid-name1-test_.cc",
             "googletest-param-test-invalid-name2-test_.cc",
+            "googletest-param-test-test",
+            "googletest-param-test-test.cc",
+            "googletest-param-test2-test.cc",
+            "googletest-setuptestsuite-test_.cc",
+            "googletest-shuffle-test_.cc",
+            "googletest-throw-on-failure-test_.cc",
+            "googletest-uninitialized-test_.cc",
+            "googletest/src/gtest-all.cc",
+            "gtest-death-test_ex_test.cc",
+            "gtest-listener_test.cc",
+            "gtest-unittest-api_test.cc",
+            "gtest_all_test.cc",
+            # go/keep-sorted end
         ],
     ) + select({
         "//:windows": [],
@@ -323,6 +326,26 @@ cc_binary(
     deps = ["//:gtest"],
 )
 
+cc_binary(
+    name = "googletest-fail-if-no-test-linked-test-without-test_",
+    testonly = 1,
+    deps = ["//:gtest_main"],
+)
+
+cc_binary(
+    name = "googletest-fail-if-no-test-linked-test-with-disabled-test_",
+    testonly = 1,
+    srcs = ["googletest-fail-if-no-test-linked-test-with-disabled-test_.cc"],
+    deps = ["//:gtest_main"],
+)
+
+cc_binary(
+    name = "googletest-fail-if-no-test-linked-test-with-enabled-test_",
+    testonly = 1,
+    srcs = ["googletest-fail-if-no-test-linked-test-with-enabled-test_.cc"],
+    deps = ["//:gtest_main"],
+)
+
 cc_test(
     name = "gtest_skip_test",
     size = "small",
@@ -363,6 +386,18 @@ py_test(
     deps = [":gtest_test_utils"],
 )
 
+py_test(
+    name = "googletest-fail-if-no-test-linked-test",
+    size = "small",
+    srcs = ["googletest-fail-if-no-test-linked-test.py"],
+    data = [
+        ":googletest-fail-if-no-test-linked-test-with-disabled-test_",
+        ":googletest-fail-if-no-test-linked-test-with-enabled-test_",
+        ":googletest-fail-if-no-test-linked-test-without-test_",
+    ],
+    deps = [":gtest_test_utils"],
+)
+
 cc_binary(
     name = "googletest-shuffle-test_",
     srcs = ["googletest-shuffle-test_.cc"],

googletest/test/googletest-fail-if-no-test-linked-test-with-disabled-test_.cc

@@ -0,0 +1,38 @@
+// Copyright 2025, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Unit test for Google Test's --gtest_fail_if_no_test_linked flag.
+//
+// This program will be invoked from a Python test.
+// Don't run it directly.
+
+#include "gtest/gtest.h"
+
+// A dummy test that is disabled.
+TEST(SomeTest, DISABLED_Test1) {}

googletest/test/googletest-fail-if-no-test-linked-test-with-enabled-test_.cc

@@ -0,0 +1,38 @@
+// Copyright 2025, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Unit test for Google Test's --gtest_fail_if_no_test_linked flag.
+//
+// This program will be invoked from a Python test.
+// Don't run it directly.
+
+#include "gtest/gtest.h"
+
+// A dummy test that is enabled.
+TEST(SomeTest, Test1) {}

googletest/test/googletest-fail-if-no-test-linked-test.py

@@ -0,0 +1,114 @@
+#!/usr/bin/env python3  # pylint: disable=g-interpreter-mismatch
+#
+# Copyright 2025, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Tests for Google Test's --gtest_fail_if_no_test_linked flag."""
+
+from googletest.test import gtest_test_utils
+
+# The command line flag for enabling the fail-if-no-test-linked behavior.
+FAIL_IF_NO_TEST_LINKED_FLAG = "gtest_fail_if_no_test_linked"
+
+
+class GTestFailIfNoTestLinkedTest(gtest_test_utils.TestCase):
+  """Tests the --gtest_fail_if_no_test_linked flag."""
+
+  def Run(self, program_name, flag=None):
+    """Run the given program with the given flag.
+
+    Args:
+      program_name: Name of the program to run.
+      flag: The command line flag to pass to the program, or None.
+
+    Returns:
+      True if the program exits with code 0, false otherwise.
+    """
+
+    exe_path = gtest_test_utils.GetTestExecutablePath(program_name)
+    args = [exe_path]
+    if flag is not None:
+      args += [flag]
+    process = gtest_test_utils.Subprocess(args, capture_stderr=False)
+    return process.exited and process.exit_code == 0
+
+  def testSucceedsIfNoTestLinkedAndFlagNotSpecified(self):
+    """Tests the behavior of no test linked and flag not specified."""
+
+    self.assertTrue(
+        self.Run("googletest-fail-if-no-test-linked-test-without-test_")
+    )
+
+  def testFailsIfNoTestLinkedAndFlagSpecified(self):
+    """Tests the behavior of no test linked and flag specified."""
+
+    self.assertFalse(
+        self.Run(
+            "googletest-fail-if-no-test-linked-test-without-test_",
+            f"--{FAIL_IF_NO_TEST_LINKED_FLAG}",
+        )
+    )
+
+  def testSucceedsIfEnabledTestLinkedAndFlagNotSpecified(self):
+    """Tests the behavior of enabled test linked and flag not specified."""
+
+    self.assertTrue(
+        self.Run("googletest-fail-if-no-test-linked-test-with-enabled-test_")
+    )
+
+  def testSucceedsIfEnabledTestLinkedAndFlagSpecified(self):
+    """Tests the behavior of enabled test linked and flag specified."""
+
+    self.assertTrue(
+        self.Run(
+            "googletest-fail-if-no-test-linked-test-with-enabled-test_",
+            f"--{FAIL_IF_NO_TEST_LINKED_FLAG}",
+        )
+    )
+
+  def testSucceedsIfDisabledTestLinkedAndFlagNotSpecified(self):
+    """Tests the behavior of disabled test linked and flag not specified."""
+
+    self.assertTrue(
+        self.Run("googletest-fail-if-no-test-linked-test-with-disabled-test_")
+    )
+
+  def testSucceedsIfDisabledTestLinkedAndFlagSpecified(self):
+    """Tests the behavior of disabled test linked and flag specified."""
+
+    self.assertTrue(
+        self.Run(
+            "googletest-fail-if-no-test-linked-test-with-disabled-test_",
+            f"--{FAIL_IF_NO_TEST_LINKED_FLAG}",
+        )
+    )
+
+
+if __name__ == "__main__":
+  gtest_test_utils.Main()