src/dawn/tests/unittests/wire/WireFutureTest.h

// Copyright 2023 The Dawn & Tint Authors
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#ifndef SRC_DAWN_TESTS_UNITTESTS_WIRE_WIREFUTURETEST_H_
#define SRC_DAWN_TESTS_UNITTESTS_WIRE_WIREFUTURETEST_H_

#include <array>
#include <string>
#include <utility>
#include <vector>

#include "dawn/common/FutureUtils.h"
#include "dawn/tests/MockCallback.h"
#include "dawn/tests/ParamGenerator.h"
#include "dawn/tests/unittests/wire/WireTest.h"
#include "dawn/wire/WireServer.h"
#include "gtest/gtest.h"

namespace dawn::wire {

struct WireFutureTestParam {
    wgpu::CallbackMode callbackMode;
};
std::ostream& operator<<(std::ostream& os, const WireFutureTestParam& param);
inline constexpr std::array kWgpuCallbackModes = {
    WireFutureTestParam{wgpu::CallbackMode::WaitAnyOnly},
    WireFutureTestParam{wgpu::CallbackMode::AllowProcessEvents},
    WireFutureTestParam{wgpu::CallbackMode::AllowSpontaneous}};

template <typename Param, typename... Params>
auto MakeParamGenerator(std::initializer_list<Params>&&... params) {
    return ParamGenerator<Param, WireFutureTestParam, Params...>(
        std::vector<WireFutureTestParam>(kWgpuCallbackModes.begin(), kWgpuCallbackModes.end()),
        std::forward<std::initializer_list<Params>&&>(params)...);
}

// Usage: DAWN_WIRE_FUTURE_TEST_PARAM_STRUCT(Foo, TypeA, TypeB, ...)
// Generate a test param struct called Foo which extends WireFutureTestParam and generated
// struct _Dawn_Foo. _Dawn_Foo has members of types TypeA, TypeB, etc. which are named mTypeA,
// mTypeB, etc. in the order they are placed in the macro argument list. Struct Foo should be
// constructed with an WireFutureTestParam as the first argument, followed by a list of values
// to initialize the base _Dawn_Foo struct.
// It is recommended to use alias declarations so that stringified types are more readable.
// Example:
//   using MyParam = unsigned int;
//   DAWN_WIRE_FUTURE_TEST_PARAM_STRUCT(FooParams, MyParam);
#define DAWN_WIRE_FUTURE_TEST_PARAM_STRUCT(StructName, ...) \
    DAWN_TEST_PARAM_STRUCT_BASE(WireFutureTestParam, StructName, __VA_ARGS__)

#define DAWN_INSTANTIATE_WIRE_FUTURE_TEST_P(testName, ...)                                   \
    INSTANTIATE_TEST_SUITE_P(                                                                \
        , testName, testing::ValuesIn(MakeParamGenerator<testName::ParamType>(__VA_ARGS__)), \
        &TestParamToString<testName::ParamType>)

template <typename Params = WireFutureTestParam>
class WireFutureTestWithParamsBase : public WireTest, public testing::WithParamInterface<Params> {
  protected:
    using testing::WithParamInterface<Params>::GetParam;

    bool IsSpontaneous() { return GetParam().callbackMode == wgpu::CallbackMode::AllowSpontaneous; }

    // Future suite adds the following flush mechanics for test writers so that they can have fine
    // grained control over when expectations should be set and verified.
    //
    // FlushFutures ensures that all futures become ready regardless of callback mode, while
    // FlushCallbacks ensures that all callbacks that were ready have been called. In most cases,
    // the intended use-case would look as follows:
    //
    //     // Call the API under test
    //     CallImpl(mockCb, this, args...);
    //     EXPECT_CALL(api, OnAsyncAPI(...)).WillOnce(InvokeWithoutArgs([&] {
    //         api.CallAsyncAPICallback(...);
    //     }));
    //
    //     FlushClient();
    //     FlushFutures(); // Ensures that the callbacks are ready (if applicable), but NOT called.
    //     EXPECT_CALL(mockCb, Call(...));
    //     FlushCallbacks();  // Calls the callbacks
    //
    // Note that in the example above we don't explicitly every call FlushServer and in most cases
    // that is probably the way to go because for Async and Spontaneous events, FlushServer will
    // actually trigger the callback. So instead, it is likely that the intention is instead to
    // break the calls into FlushFutures and FlushCallbacks for more control.
    void FlushFutures() {
        // For non-spontaneous callback modes, we need the flush the server in order for
        // the futures to become ready. For spontaneous modes, however, we don't flush the
        // server yet because that would also trigger the callback immediately.
        if (GetParam().callbackMode != wgpu::CallbackMode::AllowSpontaneous) {
            WireTest::FlushServer();
        }
    }
    void FlushCallbacks() {
        // Flushing the server will cause Spontaneous callbacks to trigger right away.
        WireTest::FlushServer();

        wgpu::CallbackMode callbackMode = GetParam().callbackMode;
        if (callbackMode == wgpu::CallbackMode::WaitAnyOnly) {
            if (mFutureIDs.empty()) {
                return;
            }
            std::vector<wgpu::FutureWaitInfo> waitInfos;
            for (auto futureID : mFutureIDs) {
                waitInfos.push_back({{futureID}, false});
            }
            EXPECT_EQ(instance.WaitAny(mFutureIDs.size(), waitInfos.data(), 0),
                      wgpu::WaitStatus::Success);
        } else if (callbackMode == wgpu::CallbackMode::AllowProcessEvents) {
            instance.ProcessEvents();
        }
    }

    std::vector<FutureID> mFutureIDs;
};

template <typename Callback, typename Params = WireFutureTestParam>
class WireFutureTestWithParams : public WireFutureTestWithParamsBase<Params> {
  protected:
    // In order to tightly bound when callbacks are expected to occur, test writers only have access
    // to the mock callback via the argument passed usually via a lamdba. The 'exp' lambda should
    // generally be a block of expectations on the mock callback followed by one statement where we
    // expect the callbacks to be called from. If the callbacks do not occur in the scope of the
    // lambda, the mock will fail the test.
    //
    // Usage:
    //   ExpectWireCallbackWhen([&](auto& mockCb) {
    //       // Set scoped expectations on the mock callback.
    //       EXPECT_CALL(mockCb, Call).Times(1);
    //
    //       // Call the statement where we want to ensure the callbacks occur.
    //       FlushCallbacks();
    //   });
    void ExpectWireCallbacksWhen(std::function<void(testing::MockCppCallback<Callback>&)> exp) {
        exp(mMockCb);
        ASSERT_TRUE(testing::Mock::VerifyAndClearExpectations(&mMockCb));
    }

    testing::MockCppCallback<Callback> mMockCb;
};

template <typename Callback>
using WireFutureTest = WireFutureTestWithParams<Callback>;

}  // namespace dawn::wire

#endif  // SRC_DAWN_TESTS_UNITTESTS_WIRE_WIREFUTURETEST_H_