Googletest export

Detect when C++ parametric tests (TEST_P) are not instantiated.

When an un-instantiated TEST_P is found, a new test will be inserted that will emit a warning message.

This can be made to error with minor code edits.
In the future, that is intended to be the default.

PiperOrigin-RevId: 284901666

Author: Abseil Team

googletest/include/gtest/internal/gtest-param-util.h

@@ -42,12 +42,14 @@
 #include <memory>
 #include <set>
 #include <tuple>
+#include <type_traits>
 #include <utility>
 #include <vector>
 
 #include "gtest/internal/gtest-internal.h"
 #include "gtest/internal/gtest-port.h"
 #include "gtest/gtest-printers.h"
+#include "gtest/gtest-test-part.h"
 
 namespace testing {
 // Input to a parameterized test name generator, describing a test parameter.
@@ -472,6 +474,8 @@ class ParameterizedTestSuiteInfoBase {
   GTEST_DISALLOW_COPY_AND_ASSIGN_(ParameterizedTestSuiteInfoBase);
 };
 
+void InsertSyntheticTestCase(const std::string &name, CodeLocation location);
+
 // INTERNAL IMPLEMENTATION - DO NOT USE IN USER CODE.
 //
 // ParameterizedTestSuiteInfo accumulates tests obtained from TEST_P
@@ -522,11 +526,13 @@ class ParameterizedTestSuiteInfo : public ParameterizedTestSuiteInfoBase {
     return 0;  // Return value used only to run this method in namespace scope.
   }
   // UnitTest class invokes this method to register tests in this test suite
-  // test suites right before running tests in RUN_ALL_TESTS macro.
+  // right before running tests in RUN_ALL_TESTS macro.
   // This method should not be called more than once on any single
   // instance of a ParameterizedTestSuiteInfoBase derived class.
   // UnitTest has a guard to prevent from calling this method more than once.
   void RegisterTests() override {
+    bool generated_instantiations = false;
+
     for (typename TestInfoContainer::iterator test_it = tests_.begin();
          test_it != tests_.end(); ++test_it) {
       std::shared_ptr<TestInfo> test_info = *test_it;
@@ -549,6 +555,8 @@ class ParameterizedTestSuiteInfo : public ParameterizedTestSuiteInfoBase {
         for (typename ParamGenerator<ParamType>::iterator param_it =
                  generator.begin();
              param_it != generator.end(); ++param_it, ++i) {
+          generated_instantiations = true;
+
           Message test_name_stream;
 
           std::string param_name = name_func(
@@ -577,6 +585,11 @@ class ParameterizedTestSuiteInfo : public ParameterizedTestSuiteInfoBase {
         }  // for param_it
       }  // for gen_it
     }  // for test_it
+
+    if (!generated_instantiations) {
+      // There are no generaotrs, or they all generate nothing ...
+      InsertSyntheticTestCase(GetTestSuiteName(), code_location_);
+    }
   }    // RegisterTests
 
  private:

googletest/src/gtest.cc

@@ -407,6 +407,66 @@ void AssertHelper::operator=(const Message& message) const {
                       );  // NOLINT
 }
 
+namespace {
+
+// When TEST_P is found without a matching INSTANTIATE_TEST_SUITE_P
+// to creates test cases for it, a syntetic test case is
+// inserted to report ether an error or a log message.
+//
+// This configuration bit will likely be removed at some point.
+constexpr bool kErrorOnUninstantiatedParameterizedTest = false;
+
+// A test that fails at a given file/line location with a given message.
+class FailureTest : public Test {
+ public:
+  explicit FailureTest(const CodeLocation& loc, std::string error_message,
+                       bool as_error)
+      : loc_(loc),
+        error_message_(std::move(error_message)),
+        as_error_(as_error) {}
+
+  void TestBody() override {
+    if (as_error_) {
+      AssertHelper(TestPartResult::kNonFatalFailure, loc_.file.c_str(),
+                   loc_.line, "") = Message() << error_message_;
+    } else {
+      std::cout << error_message_ << std::endl;
+    }
+  }
+
+ private:
+  const CodeLocation loc_;
+  const std::string error_message_;
+  const bool as_error_;
+};
+
+
+}  // namespace
+
+// If this parameterized test suite has no instantiations (and that
+// has not been marked as okay), emit a test case reporting that.
+void InsertSyntheticTestCase(const std::string &name, CodeLocation location) {
+  std::string message =
+      "Paramaterized test suite " + name +
+      " is defined via TEST_P, but never instantiated. None of the test cases "
+      "will run. Either no INSTANTIATE_TEST_SUITE_P is provided or the only "
+      "ones provided expand to nothing."
+      "\n\n"
+      "Ideally, TEST_P definitions should only ever be included as part of "
+      "binaries that intend to use them. (As opposed to, for example, being "
+      "placed in a library that may be linked in to get other utilities.)";
+
+  std::string full_name = "UninstantiatedParamaterizedTestSuite<" + name + ">";
+  RegisterTest(  //
+      "GoogleTestVerification", full_name.c_str(),
+      nullptr,  // No type parameter.
+      nullptr,  // No value parameter.
+      location.file.c_str(), location.line, [message, location] {
+        return new FailureTest(location, message,
+                               kErrorOnUninstantiatedParameterizedTest);
+      });
+}
+
 // A copy of all command line arguments.  Set by InitGoogleTest().
 static ::std::vector<std::string> g_argvs;
 

googletest/test/googletest-output-test-golden-lin.txt

@@ -12,7 +12,7 @@ Expected equality of these values:
   3
 Stack trace: (omitted)
 
-[==========] Running 84 tests from 39 test suites.
+[==========] Running 85 tests from 40 test suites.
 [----------] Global test environment set-up.
 FooEnvironment::SetUp() called.
 BarEnvironment::SetUp() called.
@@ -979,6 +979,12 @@ Expected failure
 Stack trace: (omitted)
 
 [  FAILED  ] PrintingStrings/ParamTest.Failure/a, where GetParam() = "a"
+[----------] 1 test from GoogleTestVerification
+[ RUN      ] GoogleTestVerification.UninstantiatedParamaterizedTestSuite<DetectNotInstantiatedTest>
+Paramaterized test suite DetectNotInstantiatedTest is defined via TEST_P, but never instantiated. None of the test cases will run. Either no INSTANTIATE_TEST_SUITE_P is provided or the only ones provided expand to nothing.
+
+Ideally, TEST_P definitions should only ever be included as part of binaries that intend to use them. (As opposed to, for example, being placed in a library that may be linked in to get other utilities.)
+[       OK ] GoogleTestVerification.UninstantiatedParamaterizedTestSuite<DetectNotInstantiatedTest>
 [----------] Global test environment tear-down
 BarEnvironment::TearDown() called.
 googletest-output-test_.cc:#: Failure
@@ -992,8 +998,8 @@ Failed
 Expected fatal failure.
 Stack trace: (omitted)
 
-[==========] 84 tests from 39 test suites ran.
-[  PASSED  ] 30 tests.
+[==========] 85 tests from 40 test suites ran.
+[  PASSED  ] 31 tests.
 [  FAILED  ] 54 tests, listed below:
 [  FAILED  ] NonfatalFailureTest.EscapesStringOperands
 [  FAILED  ] NonfatalFailureTest.DiffForLongStrings

googletest/test/googletest-output-test_.cc

@@ -782,6 +782,13 @@ INSTANTIATE_TEST_SUITE_P(PrintingStrings,
                          testing::Values(std::string("a")),
                          ParamNameFunc);
 
+// fails under kErrorOnUninstantiatedParameterizedTest=true
+class DetectNotInstantiatedTest : public testing::TestWithParam<int> {};
+TEST_P(DetectNotInstantiatedTest, Used) { }
+
+// This would make the test failure from the above go away.
+// INSTANTIATE_TEST_SUITE_P(Fix, DetectNotInstantiatedTest, testing::Values(1));
+
 // This #ifdef block tests the output of typed tests.
 #if GTEST_HAS_TYPED_TEST
 

googletest/test/googletest-param-test-test.cc

@@ -1068,6 +1068,12 @@ TEST_P(MyEnumTest, ChecksParamMoreThanZero) { EXPECT_GE(10, GetParam()); }
 INSTANTIATE_TEST_SUITE_P(MyEnumTests, MyEnumTest,
                          ::testing::Values(ENUM1, ENUM2, 0));
 
+namespace works_here {
+// Never used not instantiated, this should work.
+class NotUsedTest : public testing::TestWithParam<int> {};
+
+}  // namespace works_here
+
 int main(int argc, char **argv) {
   // Used in TestGenerationTest test suite.
   AddGlobalTestEnvironment(TestGenerationTest::Environment::Instance());