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1 //
2 // Copyright 2019 The Abseil Authors.
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 //
8 //      https://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15 
16 #ifndef ABSL_RANDOM_INTERNAL_MOCK_OVERLOAD_SET_H_
17 #define ABSL_RANDOM_INTERNAL_MOCK_OVERLOAD_SET_H_
18 
19 #include <type_traits>
20 
21 #include "gmock/gmock.h"
22 #include "gtest/gtest.h"
23 #include "absl/random/internal/mock_helpers.h"
24 #include "absl/random/mocking_bit_gen.h"
25 
26 namespace absl {
27 ABSL_NAMESPACE_BEGIN
28 namespace random_internal {
29 
30 template <typename DistrT, typename Fn>
31 struct MockSingleOverload;
32 
33 // MockSingleOverload
34 //
35 // MockSingleOverload hooks in to gMock's `ON_CALL` and `EXPECT_CALL` macros.
36 // EXPECT_CALL(mock_single_overload, Call(...))` will expand to a call to
37 // `mock_single_overload.gmock_Call(...)`. Because expectations are stored on
38 // the MockingBitGen (an argument passed inside `Call(...)`), this forwards to
39 // arguments to MockingBitGen::Register.
40 //
41 // The underlying KeyT must match the KeyT constructed by DistributionCaller.
42 template <typename DistrT, typename Ret, typename... Args>
43 struct MockSingleOverload<DistrT, Ret(MockingBitGen&, Args...)> {
44   static_assert(std::is_same<typename DistrT::result_type, Ret>::value,
45                 "Overload signature must have return type matching the "
46                 "distribution result_type.");
47   using KeyT = Ret(DistrT, std::tuple<Args...>);
48   auto gmock_Call(
49       absl::MockingBitGen& gen,  // NOLINT(google-runtime-references)
50       const ::testing::Matcher<Args>&... matchers)
51       -> decltype(MockHelpers::MockFor<KeyT>(gen).gmock_Call(matchers...)) {
52     return MockHelpers::MockFor<KeyT>(gen).gmock_Call(matchers...);
53   }
54 };
55 
56 template <typename DistrT, typename Ret, typename Arg, typename... Args>
57 struct MockSingleOverload<DistrT, Ret(Arg, MockingBitGen&, Args...)> {
58   static_assert(std::is_same<typename DistrT::result_type, Ret>::value,
59                 "Overload signature must have return type matching the "
60                 "distribution result_type.");
61   using KeyT = Ret(DistrT, std::tuple<Arg, Args...>);
62   auto gmock_Call(
63       const ::testing::Matcher<Arg>& matcher,
64       absl::MockingBitGen& gen,  // NOLINT(google-runtime-references)
65       const ::testing::Matcher<Args>&... matchers)
66       -> decltype(MockHelpers::MockFor<KeyT>(gen).gmock_Call(matcher,
67                                                              matchers...)) {
68     return MockHelpers::MockFor<KeyT>(gen).gmock_Call(matcher, matchers...);
69   }
70 };
71 
72 // MockOverloadSet
73 //
74 // MockOverloadSet takes a distribution and a collection of signatures and
75 // performs overload resolution amongst all the overloads. This makes
76 // `EXPECT_CALL(mock_overload_set, Call(...))` expand and do overload resolution
77 // correctly.
78 template <typename DistrT, typename... Signatures>
79 struct MockOverloadSet;
80 
81 template <typename DistrT, typename Sig>
82 struct MockOverloadSet<DistrT, Sig> : public MockSingleOverload<DistrT, Sig> {
83   using MockSingleOverload<DistrT, Sig>::gmock_Call;
84 };
85 
86 template <typename DistrT, typename FirstSig, typename... Rest>
87 struct MockOverloadSet<DistrT, FirstSig, Rest...>
88     : public MockSingleOverload<DistrT, FirstSig>,
89       public MockOverloadSet<DistrT, Rest...> {
90   using MockSingleOverload<DistrT, FirstSig>::gmock_Call;
91   using MockOverloadSet<DistrT, Rest...>::gmock_Call;
92 };
93 
94 }  // namespace random_internal
95 ABSL_NAMESPACE_END
96 }  // namespace absl
97 #endif  // ABSL_RANDOM_INTERNAL_MOCK_OVERLOAD_SET_H_
98