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// Copyright 2022 The Pigweed Authors
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#pragma once
#include <array>
#include <cstddef>
#include <optional>
#include "pw_bytes/span.h"
#include "pw_containers/to_array.h"
#include "pw_spi/initiator.h"
namespace pw::spi {
// Represents a complete parameter set for the Initiator::WriteRead().
class MockTransaction {
// Same set of parameters as Initiator::WriteRead().
constexpr MockTransaction(Status expected_return_value,
ConstByteSpan write_buffer,
ConstByteSpan read_buffer)
: return_value_(expected_return_value),
write_buffer_(write_buffer) {}
// Gets the buffer that is virtually read.
ConstByteSpan read_buffer() const { return read_buffer_; }
// Gets the buffer that should be written by the driver.
ConstByteSpan write_buffer() const { return write_buffer_; }
// Gets the expected return value.
Status return_value() const { return return_value_; }
const Status return_value_;
const ConstByteSpan read_buffer_;
const ConstByteSpan write_buffer_;
// Read transaction is a helper that constructs a read only transaction.
constexpr MockTransaction MockReadTransaction(Status expected_return_value,
ConstByteSpan read_buffer) {
return MockTransaction(expected_return_value, ConstByteSpan(), read_buffer);
// WriteTransaction is a helper that constructs a write only transaction.
constexpr MockTransaction MockWriteTransaction(Status expected_return_value,
ConstByteSpan write_buffer) {
return MockTransaction(expected_return_value, write_buffer, ConstByteSpan());
// MockInitiator takes a series of read and/or write transactions and
// compares them against user/driver input.
// This mock uses Gtest to ensure that the transactions instantiated meet
// expectations. This MockedInitiator should be instantiated inside a Gtest test
// frame.
class MockInitiator : public pw::spi::Initiator {
explicit constexpr MockInitiator(std::span<MockTransaction> transaction_list)
: expected_transactions_(transaction_list),
expected_transaction_index_(0) {}
// Should be called at the end of the test to ensure that all expected
// transactions have been met.
// Returns:
// Ok - Success.
// OutOfRange - The mocked set of transactions has not been exhausted.
Status Finalize() const {
if (expected_transaction_index_ != expected_transactions_.size()) {
return Status::OutOfRange();
return Status();
// Runs Finalize() regardless of whether it was already optionally finalized.
// Implements a mocked backend for the SPI initiator.
// Expects (via Gtest):
// tx_buffer == expected_transaction_tx_buffer
// tx_buffer.size() == expected_transaction_tx_buffer.size()
// rx_buffer.size() == expected_transaction_rx_buffer.size()
// Asserts:
// When the number of calls to this method exceed the number of expected
// transactions.
// Returns:
// Specified transaction return type
pw::Status WriteRead(pw::ConstByteSpan, pw::ByteSpan) override;
pw::Status Configure(const pw::spi::Config& /*config */) override {
return pw::OkStatus();
std::span<MockTransaction> expected_transactions_;
size_t expected_transaction_index_;
// Makes a new SPI transactions list.
template <size_t kSize>
constexpr std::array<MockTransaction, kSize> MakeExpectedTransactionArray(
const MockTransaction (&transactions)[kSize]) {
return containers::to_array(transactions);
} // namespace pw::spi