Merge pull request #2904 from AmatanHead:throw-matchers

PiperOrigin-RevId: 327294137

2 files changed, 353 insertions, 0 deletions

diff --git a/googlemock/include/gmock/gmock-matchers.h b/googlemock/include/gmock/gmock-matchers.h
index 0bc9b36..a897611 100644
--- a/googlemock/include/gmock/gmock-matchers.h
+++ b/googlemock/include/gmock/gmock-matchers.h
@@ -4725,6 +4725,175 @@ PolymorphicMatcher<internal::variant_matcher::VariantMatcher<T> > VariantWith(
       internal::variant_matcher::VariantMatcher<T>(matcher));
 }
 
+#if GTEST_HAS_EXCEPTIONS
+
+// Anything inside the `internal` namespace is internal to the implementation
+// and must not be used in user code!
+namespace internal {
+
+class WithWhatMatcherImpl {
+ public:
+  WithWhatMatcherImpl(Matcher<std::string> matcher)
+      : matcher_(std::move(matcher)) {}
+
+  void DescribeTo(std::ostream* os) const {
+    *os << "contains .what() that ";
+    matcher_.DescribeTo(os);
+  }
+
+  void DescribeNegationTo(std::ostream* os) const {
+    *os << "contains .what() that does not ";
+    matcher_.DescribeTo(os);
+  }
+
+  template <typename Err>
+  bool MatchAndExplain(const Err& err, MatchResultListener* listener) const {
+    *listener << "which contains .what() that ";
+    return matcher_.MatchAndExplain(err.what(), listener);
+  }
+
+ private:
+  const Matcher<std::string> matcher_;
+};
+
+inline PolymorphicMatcher<WithWhatMatcherImpl> WithWhat(
+    Matcher<std::string> m) {
+  return MakePolymorphicMatcher(WithWhatMatcherImpl(std::move(m)));
+}
+
+template <typename Err>
+class ExceptionMatcherImpl {
+  class NeverThrown {
+   public:
+    const char* what() const noexcept {
+      return "this exception should never be thrown";
+    }
+  };
+
+  // If the matchee raises an exception of a wrong type, we'd like to
+  // catch it and print its message and type. To do that, we add an additional
+  // catch clause:
+  //
+  //     try { ... }
+  //     catch (const Err&) { /* an expected exception */ }
+  //     catch (const std::exception&) { /* exception of a wrong type */ }
+  //
+  // However, if the `Err` itself is `std::exception`, we'd end up with two
+  // identical `catch` clauses:
+  //
+  //     try { ... }
+  //     catch (const std::exception&) { /* an expected exception */ }
+  //     catch (const std::exception&) { /* exception of a wrong type */ }
+  //
+  // This can cause a warning or an error in some compilers. To resolve
+  // the issue, we use a fake error type whenever `Err` is `std::exception`:
+  //
+  //     try { ... }
+  //     catch (const std::exception&) { /* an expected exception */ }
+  //     catch (const NeverThrown&) { /* exception of a wrong type */ }
+  using DefaultExceptionType = typename std::conditional<
+      std::is_same<typename std::remove_cv<
+                       typename std::remove_reference<Err>::type>::type,
+                   std::exception>::value,
+      const NeverThrown&, const std::exception&>::type;
+
+ public:
+  ExceptionMatcherImpl(Matcher<const Err&> matcher)
+      : matcher_(std::move(matcher)) {}
+
+  void DescribeTo(std::ostream* os) const {
+    *os << "throws an exception which is a " << GetTypeName<Err>();
+    *os << " which ";
+    matcher_.DescribeTo(os);
+  }
+
+  void DescribeNegationTo(std::ostream* os) const {
+    *os << "throws an exception which is not a " << GetTypeName<Err>();
+    *os << " which ";
+    matcher_.DescribeNegationTo(os);
+  }
+
+  template <typename T>
+  bool MatchAndExplain(T&& x, MatchResultListener* listener) const {
+    try {
+      (void)(std::forward<T>(x)());
+    } catch (const Err& err) {
+      *listener << "throws an exception which is a " << GetTypeName<Err>();
+      *listener << " ";
+      return matcher_.MatchAndExplain(err, listener);
+    } catch (DefaultExceptionType err) {
+#if GTEST_HAS_RTTI
+      *listener << "throws an exception of type " << GetTypeName(typeid(err));
+      *listener << " ";
+#else
+      *listener << "throws an std::exception-derived type ";
+#endif
+      *listener << "with description \"" << err.what() << "\"";
+      return false;
+    } catch (...) {
+      *listener << "throws an exception of an unknown type";
+      return false;
+    }
+
+    *listener << "does not throw any exception";
+    return false;
+  }
+
+ private:
+  const Matcher<const Err&> matcher_;
+};
+
+}  // namespace internal
+
+// Throws()
+// Throws(exceptionMatcher)
+// ThrowsMessage(messageMatcher)
+//
+// This matcher accepts a callable and verifies that when invoked, it throws
+// an exception with the given type and properties.
+//
+// Examples:
+//
+//   EXPECT_THAT(
+//       []() { throw std::runtime_error("message"); },
+//       Throws<std::runtime_error>());
+//
+//   EXPECT_THAT(
+//       []() { throw std::runtime_error("message"); },
+//       ThrowsMessage<std::runtime_error>(HasSubstr("message")));
+//
+//   EXPECT_THAT(
+//       []() { throw std::runtime_error("message"); },
+//       Throws<std::runtime_error>(
+//           Property(&std::runtime_error::what, HasSubstr("message"))));
+
+template <typename Err>
+PolymorphicMatcher<internal::ExceptionMatcherImpl<Err>> Throws() {
+  return MakePolymorphicMatcher(
+      internal::ExceptionMatcherImpl<Err>(A<const Err&>()));
+}
+
+template <typename Err, typename ExceptionMatcher>
+PolymorphicMatcher<internal::ExceptionMatcherImpl<Err>> Throws(
+    const ExceptionMatcher& exception_matcher) {
+  // Using matcher cast allows users to pass a matcher of a more broad type.
+  // For example user may want to pass Matcher<std::exception>
+  // to Throws<std::runtime_error>, or Matcher<int64> to Throws<int32>.
+  return MakePolymorphicMatcher(internal::ExceptionMatcherImpl<Err>(
+      SafeMatcherCast<const Err&>(exception_matcher)));
+}
+
+template <typename Err, typename MessageMatcher>
+PolymorphicMatcher<internal::ExceptionMatcherImpl<Err>> ThrowsMessage(
+    MessageMatcher&& message_matcher) {
+  static_assert(std::is_base_of<std::exception, Err>::value,
+                "expected an std::exception-derived type");
+  return Throws<Err>(internal::WithWhat(
+      MatcherCast<std::string>(std::forward<MessageMatcher>(message_matcher))));
+}
+
+#endif  // GTEST_HAS_EXCEPTIONS
+
 // These macros allow using matchers to check values in Google Test
 // tests.  ASSERT_THAT(value, matcher) and EXPECT_THAT(value, matcher)
 // succeed if and only if the value matches the matcher.  If the assertion
diff --git a/googlemock/test/gmock-matchers_test.cc b/googlemock/test/gmock-matchers_test.cc
index 015bb09..1cba156 100644
--- a/googlemock/test/gmock-matchers_test.cc
+++ b/googlemock/test/gmock-matchers_test.cc
@@ -8117,6 +8117,190 @@ TEST(MatcherPMacroTest, WorksOnMoveOnlyType) {
   EXPECT_THAT(p, Not(UniquePointee(2)));
 }
 
+#if GTEST_HAS_EXCEPTIONS
+
+// std::function<void()> is used below for compatibility with older copies of
+// GCC. Normally, a raw lambda is all that is needed.
+
+// Test that examples from documentation compile
+TEST(ThrowsTest, Examples) {
+  EXPECT_THAT(
+      std::function<void()>([]() { throw std::runtime_error("message"); }),
+      Throws<std::runtime_error>());
+
+  EXPECT_THAT(
+      std::function<void()>([]() { throw std::runtime_error("message"); }),
+      ThrowsMessage<std::runtime_error>(HasSubstr("message")));
+}
+
+TEST(ThrowsTest, DoesNotGenerateDuplicateCatchClauseWarning) {
+  EXPECT_THAT(std::function<void()>([]() { throw std::exception(); }),
+              Throws<std::exception>());
+}
+
+TEST(ThrowsTest, CallableExecutedExactlyOnce) {
+  size_t a = 0;
+
+  EXPECT_THAT(std::function<void()>([&a]() {
+                a++;
+                throw 10;
+              }),
+              Throws<int>());
+  EXPECT_EQ(a, 1u);
+
+  EXPECT_THAT(std::function<void()>([&a]() {
+                a++;
+                throw std::runtime_error("message");
+              }),
+              Throws<std::runtime_error>());
+  EXPECT_EQ(a, 2u);
+
+  EXPECT_THAT(std::function<void()>([&a]() {
+                a++;
+                throw std::runtime_error("message");
+              }),
+              ThrowsMessage<std::runtime_error>(HasSubstr("message")));
+  EXPECT_EQ(a, 3u);
+
+  EXPECT_THAT(std::function<void()>([&a]() {
+                a++;
+                throw std::runtime_error("message");
+              }),
+              Throws<std::runtime_error>(
+                  Property(&std::runtime_error::what, HasSubstr("message"))));
+  EXPECT_EQ(a, 4u);
+}
+
+TEST(ThrowsTest, Describe) {
+  Matcher<std::function<void()>> matcher = Throws<std::runtime_error>();
+  std::stringstream ss;
+  matcher.DescribeTo(&ss);
+  auto explanation = ss.str();
+  EXPECT_THAT(explanation, HasSubstr("std::runtime_error"));
+}
+
+TEST(ThrowsTest, Success) {
+  Matcher<std::function<void()>> matcher = Throws<std::runtime_error>();
+  StringMatchResultListener listener;
+  EXPECT_TRUE(matcher.MatchAndExplain(
+      []() { throw std::runtime_error("error message"); }, &listener));
+  EXPECT_THAT(listener.str(), HasSubstr("std::runtime_error"));
+}
+
+TEST(ThrowsTest, FailWrongType) {
+  Matcher<std::function<void()>> matcher = Throws<std::runtime_error>();
+  StringMatchResultListener listener;
+  EXPECT_FALSE(matcher.MatchAndExplain(
+      []() { throw std::logic_error("error message"); }, &listener));
+  EXPECT_THAT(listener.str(), HasSubstr("std::logic_error"));
+  EXPECT_THAT(listener.str(), HasSubstr("\"error message\""));
+}
+
+TEST(ThrowsTest, FailWrongTypeNonStd) {
+  Matcher<std::function<void()>> matcher = Throws<std::runtime_error>();
+  StringMatchResultListener listener;
+  EXPECT_FALSE(matcher.MatchAndExplain([]() { throw 10; }, &listener));
+  EXPECT_THAT(listener.str(),
+              HasSubstr("throws an exception of an unknown type"));
+}
+
+TEST(ThrowsTest, FailNoThrow) {
+  Matcher<std::function<void()>> matcher = Throws<std::runtime_error>();
+  StringMatchResultListener listener;
+  EXPECT_FALSE(matcher.MatchAndExplain([]() { (void)0; }, &listener));
+  EXPECT_THAT(listener.str(), HasSubstr("does not throw any exception"));
+}
+
+class ThrowsPredicateTest
+    : public TestWithParam<Matcher<std::function<void()>>> {};
+
+TEST_P(ThrowsPredicateTest, Describe) {
+  Matcher<std::function<void()>> matcher = GetParam();
+  std::stringstream ss;
+  matcher.DescribeTo(&ss);
+  auto explanation = ss.str();
+  EXPECT_THAT(explanation, HasSubstr("std::runtime_error"));
+  EXPECT_THAT(explanation, HasSubstr("error message"));
+}
+
+TEST_P(ThrowsPredicateTest, Success) {
+  Matcher<std::function<void()>> matcher = GetParam();
+  StringMatchResultListener listener;
+  EXPECT_TRUE(matcher.MatchAndExplain(
+      []() { throw std::runtime_error("error message"); }, &listener));
+  EXPECT_THAT(listener.str(), HasSubstr("std::runtime_error"));
+}
+
+TEST_P(ThrowsPredicateTest, FailWrongType) {
+  Matcher<std::function<void()>> matcher = GetParam();
+  StringMatchResultListener listener;
+  EXPECT_FALSE(matcher.MatchAndExplain(
+      []() { throw std::logic_error("error message"); }, &listener));
+  EXPECT_THAT(listener.str(), HasSubstr("std::logic_error"));
+  EXPECT_THAT(listener.str(), HasSubstr("\"error message\""));
+}
+
+TEST_P(ThrowsPredicateTest, FailWrongTypeNonStd) {
+  Matcher<std::function<void()>> matcher = GetParam();
+  StringMatchResultListener listener;
+  EXPECT_FALSE(matcher.MatchAndExplain([]() { throw 10; }, &listener));
+  EXPECT_THAT(listener.str(),
+              HasSubstr("throws an exception of an unknown type"));
+}
+
+TEST_P(ThrowsPredicateTest, FailWrongMessage) {
+  Matcher<std::function<void()>> matcher = GetParam();
+  StringMatchResultListener listener;
+  EXPECT_FALSE(matcher.MatchAndExplain(
+      []() { throw std::runtime_error("wrong message"); }, &listener));
+  EXPECT_THAT(listener.str(), HasSubstr("std::runtime_error"));
+  EXPECT_THAT(listener.str(), Not(HasSubstr("wrong message")));
+}
+
+TEST_P(ThrowsPredicateTest, FailNoThrow) {
+  Matcher<std::function<void()>> matcher = GetParam();
+  StringMatchResultListener listener;
+  EXPECT_FALSE(matcher.MatchAndExplain([]() {}, &listener));
+  EXPECT_THAT(listener.str(), HasSubstr("does not throw any exception"));
+}
+
+INSTANTIATE_TEST_SUITE_P(
+    AllMessagePredicates, ThrowsPredicateTest,
+    Values(Matcher<std::function<void()>>(
+        ThrowsMessage<std::runtime_error>(HasSubstr("error message")))));
+
+// Tests that Throws<E1>(Matcher<E2>{}) compiles even when E2 != const E1&.
+TEST(ThrowsPredicateCompilesTest, ExceptionMatcherAcceptsBroadType) {
+  {
+    Matcher<std::function<void()>> matcher =
+        ThrowsMessage<std::runtime_error>(HasSubstr("error message"));
+    EXPECT_TRUE(
+        matcher.Matches([]() { throw std::runtime_error("error message"); }));
+    EXPECT_FALSE(
+        matcher.Matches([]() { throw std::runtime_error("wrong message"); }));
+  }
+
+  {
+    Matcher<uint64_t> inner = Eq(10);
+    Matcher<std::function<void()>> matcher = Throws<uint32_t>(inner);
+    EXPECT_TRUE(matcher.Matches([]() { throw(uint32_t) 10; }));
+    EXPECT_FALSE(matcher.Matches([]() { throw(uint32_t) 11; }));
+  }
+}
+
+// Tests that ThrowsMessage("message") is equivalent
+// to ThrowsMessage(Eq<std::string>("message")).
+TEST(ThrowsPredicateCompilesTest, MessageMatcherAcceptsNonMatcher) {
+  Matcher<std::function<void()>> matcher =
+      ThrowsMessage<std::runtime_error>("error message");
+  EXPECT_TRUE(
+      matcher.Matches([]() { throw std::runtime_error("error message"); }));
+  EXPECT_FALSE(matcher.Matches(
+      []() { throw std::runtime_error("wrong error message"); }));
+}
+
+#endif  // GTEST_HAS_EXCEPTIONS
+
 }  // namespace
 }  // namespace gmock_matchers_test
 }  // namespace testing