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// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_TEST_BIND_H_
#define BASE_TEST_BIND_H_
#include <string_view>
#include <type_traits>
#include <utility>
#include "base/functional/bind.h"
namespace base {
class Location;
namespace internal {
template <typename Signature, typename R, typename F, typename... Args>
static constexpr bool kHasConstCallOperator = false;
template <typename R, typename F, typename... Args>
static constexpr bool
kHasConstCallOperator<R (F::*)(Args...) const, R, F, Args...> = true;
// Implementation of `BindLambdaForTesting()`, which checks preconditions before
// handing off to `Bind{Once,Repeating}()`.
template <typename Lambda,
typename = ExtractCallableRunType<std::decay_t<Lambda>>>
struct BindLambdaForTestingHelper;
template <typename Lambda, typename R, typename... Args>
struct BindLambdaForTestingHelper<Lambda, R(Args...)> {
private:
using F = std::decay_t<Lambda>;
// For context on this "templated struct with a lambda that asserts" pattern,
// see comments in `Invoker<>`.
template <bool v = std::is_rvalue_reference_v<Lambda&&> &&
!std::is_const_v<std::remove_reference_t<Lambda>>>
struct IsNonConstRvalueRef {
static constexpr bool value = [] {
static_assert(
v,
"BindLambdaForTesting() requires non-const rvalue for mutable lambda "
"binding, i.e. base::BindLambdaForTesting(std::move(lambda)).");
return v;
}();
};
static R Run(const F& f, Args... args) {
return f(std::forward<Args>(args)...);
}
static R RunOnce(F&& f, Args... args) {
return f(std::forward<Args>(args)...);
}
public:
static auto BindLambdaForTesting(Lambda&& lambda) {
if constexpr (kHasConstCallOperator<decltype(&F::operator()), R, F,
Args...>) {
// If WTF::BindRepeating is available, and a callback argument is in WTF,
// then this call is ambiguous without the full namespace path.
return ::base::BindRepeating(&Run, std::forward<Lambda>(lambda));
} else if constexpr (IsNonConstRvalueRef<>::value) {
// Since a mutable lambda potentially can invalidate its state after being
// run once, this method returns a `OnceCallback` instead of a
// `RepeatingCallback`.
return BindOnce(&RunOnce, std::move(lambda));
}
}
};
} // namespace internal
// A variant of `Bind{Once,Repeating}()` that can bind capturing lambdas for
// testing. This doesn't support extra arguments binding as the lambda itself
// can do.
template <typename Lambda>
auto BindLambdaForTesting(Lambda&& lambda) {
return internal::BindLambdaForTestingHelper<Lambda>::BindLambdaForTesting(
std::forward<Lambda>(lambda));
}
// Returns a closure that fails on destruction if it hasn't been run.
OnceClosure MakeExpectedRunClosure(
const Location& location,
std::string_view message = std::string_view());
RepeatingClosure MakeExpectedRunAtLeastOnceClosure(
const Location& location,
std::string_view message = std::string_view());
// Returns a closure that fails the test if run.
RepeatingClosure MakeExpectedNotRunClosure(
const Location& location,
std::string_view message = std::string_view());
} // namespace base
#endif // BASE_TEST_BIND_H_
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