has_ostream_operator_test.cc (1297B)
1 // Copyright 2023 The Abseil Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 #include "absl/strings/has_ostream_operator.h" 16 17 #include <ostream> 18 #include <string> 19 20 #include "gtest/gtest.h" 21 #include "absl/types/optional.h" 22 23 namespace { 24 25 struct TypeWithoutOstreamOp {}; 26 27 struct TypeWithOstreamOp { 28 friend std::ostream& operator<<(std::ostream& os, const TypeWithOstreamOp&) { 29 return os; 30 } 31 }; 32 33 TEST(HasOstreamOperatorTest, Works) { 34 EXPECT_TRUE(absl::HasOstreamOperator<int>::value); 35 EXPECT_TRUE(absl::HasOstreamOperator<std::string>::value); 36 EXPECT_FALSE(absl::HasOstreamOperator<absl::optional<int>>::value); 37 EXPECT_FALSE(absl::HasOstreamOperator<TypeWithoutOstreamOp>::value); 38 EXPECT_TRUE(absl::HasOstreamOperator<TypeWithOstreamOp>::value); 39 } 40 41 } // namespace