Class BadExecutor

test/test_executor.cpp:369–373

TEST_F(ExecutorTest, return_invalid_future_when_invoke_fail) {
  struct BadExecutor : public Executor {
    virtual int invoke(MoveOnlyFunction<void(void)>&&) noexcept override {
      return -1;
    }
  } executor;
  auto future = executor.execute([] {});
  ASSERT_FALSE(future.valid());
  future = async(executor, [] {});