zircon/system/ulib/zxtest/include/zxtest/base/death-statement.h

// Copyright 2019 The Fuchsia 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 ZXTEST_BASE_DEATH_STATEMENT_H_
#define ZXTEST_BASE_DEATH_STATEMENT_H_

#include <memory>
#include <string>
#include <string_view>
#include <utility>

#include <lib/fit/function.h>
#include <lib/zx/channel.h>
#include <lib/zx/port.h>
#include <zxtest/base/test-driver.h>
#include <zxtest/base/test-internal.h>
#include <zxtest/base/test.h>

namespace zxtest {
namespace internal {
// A Statement to be executed which can throw an exception.
// This statement will be executed in a separate thread. The calling thread
// will be blocked until the statement completes its execution.
//
// The statement being executed is allowed to use ASSERT_/EXPECT_ mechanisms.
class DeathStatement {
 public:
  // Possible results of executing this statement.
  enum class State {
    // Statement was never executed.
    kUnknown,
    // Statement execution started.
    kStarted,
    // Part of the setup required to execute the death statement might have failed.
    kInternalError,
    // Statement executed without exceptions.
    kSuccess,
    // Statement executed with exceptions, but handled gracefully.
    kException,
    // Statement executed with exceptions, but was not handled properly (leaked resources).
    kBadState,
  };

  DeathStatement() = delete;
  // Take ownership of the closure, explicit move semantics.
  explicit DeathStatement(fit::function<void()> statement);
  DeathStatement(const DeathStatement&) = delete;
  DeathStatement(DeathStatement&&) = default;
  DeathStatement& operator=(const DeathStatement&) = delete;
  DeathStatement& operator=(DeathStatement&&) = delete;
  ~DeathStatement() = default;

  // Executes the statement in separate thread.
  void Execute();

  // Returns the current state of the statement.
  State state() const { return state_; }

  const std::string_view error_message() const { return error_message_; }

 private:
  fit::function<void()> statement_;

  // Blocks the main thread until |event_port| receives a packet notifying that the
  // exception_channel has become readable.
  void Listen(const zx::port& event_port, const zx::channel& exception_channel);

  // Returns true if the exception was handled and false if it was ignored.
  bool HandleException(const zx::channel& exception_channel);

  // Internal error description.
  std::string error_message_;
  State state_ = State::kUnknown;
};
}  // namespace internal

}  // namespace zxtest

#endif  // ZXTEST_BASE_DEATH_STATEMENT_H_