mojo/public/cpp/test_support/test_utils.h

// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MOJO_PUBLIC_CPP_TEST_SUPPORT_TEST_UTILS_H_
#define MOJO_PUBLIC_CPP_TEST_SUPPORT_TEST_UTILS_H_

#include <string>
#include <utility>

#include "base/run_loop.h"
#include "mojo/public/cpp/bindings/message.h"
#include "mojo/public/cpp/bindings/struct_ptr.h"
#include "mojo/public/cpp/system/core.h"

namespace mojo {
namespace test {

// This overload is used for mojom structures with struct traits. The C++
// structure type is given as an input, and returned as an output.
template <typename MojomType,
          typename UserStructType,
          std::enable_if_t<!std::is_enum<UserStructType>::value, int> = 0>
bool SerializeAndDeserialize(UserStructType& input,
                             std::remove_const_t<UserStructType>& output) {
  mojo::Message message = MojomType::SerializeAsMessage(&input);

  // This accurately simulates full serialization to ensure that all attached
  // handles are serialized as well. Necessary for DeserializeFromMessage to
  // work properly.
  mojo::ScopedMessageHandle handle = message.TakeMojoMessage();
  message = mojo::Message::CreateFromMessageHandle(&handle);
  DCHECK(!message.IsNull());

  return MojomType::DeserializeFromMessage(std::move(message), &output);
}

// This overload is used for mojom structures with struct traits, but here they
// are serialized from a manually constructed StructPtr instead of from the C++
// structure using the struct traits. This allows malformed data to be put in
// the StructPtr<MojomType>, in order to verify the behaviour of deserialization
// back to the C++ structure type.
template <typename MojomType,
          typename UserStructType,
          typename MojomStructPtr,
          std::enable_if_t<
              (std::is_same<mojo::InlinedStructPtr<MojomType>,
                            std::remove_const_t<MojomStructPtr>>::value ||
               std::is_same<mojo::StructPtr<MojomType>,
                            std::remove_const_t<MojomStructPtr>>::value) &&
                  !std::is_enum<UserStructType>::value,
              int> = 0>
bool SerializeAndDeserialize(MojomStructPtr& input, UserStructType& output) {
  mojo::Message message = MojomType::SerializeAsMessage(&input);

  // This accurately simulates full serialization to ensure that all attached
  // handles are serialized as well. Necessary for DeserializeFromMessage to
  // work properly.
  mojo::ScopedMessageHandle handle = message.TakeMojoMessage();
  message = mojo::Message::CreateFromMessageHandle(&handle);
  DCHECK(!message.IsNull());

  return MojomType::DeserializeFromMessage(std::move(message), &output);
}

// This overload is used for mojom enums. The C++ enum type is given as an
// input, and returned as an output.
template <typename MojomType,
          typename UserEnumType,
          std::enable_if_t<std::is_enum<UserEnumType>::value, int> = 0>
bool SerializeAndDeserialize(UserEnumType input, UserEnumType& output) {
  MojomType mode = mojo::EnumTraits<MojomType, UserEnumType>::ToMojom(input);
  return mojo::EnumTraits<MojomType, UserEnumType>::FromMojom(mode, &output);
}

// Writes a message to |handle| with message data |text|. Returns true on
// success.
bool WriteTextMessage(const MessagePipeHandle& handle, const std::string& text);

// Reads a message from |handle|, putting its contents into |*text|. Returns
// true on success. (This blocks if necessary and will call |MojoReadMessage()|
// multiple times, e.g., to query the size of the message.)
bool ReadTextMessage(const MessagePipeHandle& handle, std::string* text);

// Discards a message from |handle|. Returns true on success. (This does not
// block. It will fail if no message is available to discard.)
bool DiscardMessage(const MessagePipeHandle& handle);

// Run |single_iteration| an appropriate number of times and report its
// performance appropriately. (This actually runs |single_iteration| for a fixed
// amount of time and reports the number of iterations per unit time.)
typedef void (*PerfTestSingleIteration)(void* closure);
void IterateAndReportPerf(const char* test_name,
                          const char* sub_test_name,
                          PerfTestSingleIteration single_iteration,
                          void* closure);

// Intercepts a single bad message (reported via mojo::ReportBadMessage or
// mojo::GetBadMessageCallback) that would be associated with the global bad
// message handler (typically when the messages originate from a test
// implementation of an interface hosted in the test process).
class BadMessageObserver {
 public:
  BadMessageObserver();

  BadMessageObserver(const BadMessageObserver&) = delete;
  BadMessageObserver& operator=(const BadMessageObserver&) = delete;

  ~BadMessageObserver();

  // Waits for the bad message and returns the error string.
  std::string WaitForBadMessage();

  // Returns true iff a bad message was already received.
  bool got_bad_message() const { return got_bad_message_; }

 private:
  void OnReportBadMessage(const std::string& message);

  std::string last_error_for_bad_message_;
  bool got_bad_message_;
  base::RunLoop run_loop_;
};

// Creates a scoped swapped implementation of a mojo Receiver. Callers should
// ensure that `new_impl` lives for longer than the lifetime of the `receiver`.
// See also `SwapImplForTesting` implementations for each receiver type.
template <typename T>
class ScopedSwapImplForTesting {
 public:
  using ImplPointerType = typename T::ImplPointerType;

  ScopedSwapImplForTesting(T& receiver, ImplPointerType new_impl)
      : receiver_(receiver) {
    old_impl_ = receiver_.SwapImplForTesting(new_impl);
  }

  ~ScopedSwapImplForTesting() {
    std::ignore = receiver_.SwapImplForTesting(old_impl_);
  }

  ImplPointerType old_impl() const { return old_impl_; }

  ScopedSwapImplForTesting(const ScopedSwapImplForTesting&) = delete;
  ScopedSwapImplForTesting& operator=(const ScopedSwapImplForTesting&) = delete;

 private:
  T& receiver_;
  ImplPointerType old_impl_;
};

}  // namespace test
}  // namespace mojo

#endif  // MOJO_PUBLIC_CPP_TEST_SUPPORT_TEST_UTILS_H_