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//===----------------------------------------------------------------------===//
//
// This source file is part of the SwiftNIO open source project
//
// Copyright (c) 2019 Apple Inc. and the SwiftNIO project authors
// Licensed under Apache License v2.0
//
// See LICENSE.txt for license information
// See CONTRIBUTORS.txt for the list of SwiftNIO project authors
//
// SPDX-License-Identifier: Apache-2.0
//
//===----------------------------------------------------------------------===//
import NIO
public enum ByteToMessageDecoderVerifier {
/// - seealso: verifyDecoder(inputOutputPairs:decoderFactory:)
///
/// Verify `ByteToMessageDecoder`s with `String` inputs
public static func verifyDecoder<Decoder: ByteToMessageDecoder>(stringInputOutputPairs: [(String, [Decoder.InboundOut])],
decoderFactory: @escaping () -> Decoder) throws where Decoder.InboundOut: Equatable {
let alloc = ByteBufferAllocator()
let ioPairs = stringInputOutputPairs.map { (ioPair: (String, [Decoder.InboundOut])) -> (ByteBuffer, [Decoder.InboundOut]) in
return (alloc.buffer(string: ioPair.0), ioPair.1)
}
return try ByteToMessageDecoderVerifier.verifyDecoder(inputOutputPairs: ioPairs, decoderFactory: decoderFactory)
}
/// Verifies a `ByteToMessageDecoder` by performing a number of tests.
///
/// This method is mostly useful in unit tests for `ByteToMessageDecoder`s. It feeds the inputs from
/// `inputOutputPairs` into the decoder in various ways and expects the decoder to produce the outputs from
/// `inputOutputPairs`.
///
/// The verification performs various tests, for example:
///
/// - drip feeding the bytes, one by one
/// - sending many messages in one `ByteBuffer`
/// - sending each complete message in one `ByteBuffer`
///
/// For `ExampleDecoder` that produces `ExampleDecoderOutput`s you would use this method the following way:
///
/// var exampleInput1 = channel.allocator.buffer(capacity: 16)
/// exampleInput1.writeString("example-in1")
/// var exampleInput2 = channel.allocator.buffer(capacity: 16)
/// exampleInput2.writeString("example-in2")
/// let expectedInOuts = [(exampleInput1, [ExampleDecoderOutput("1")]),
/// (exampleInput2, [ExampleDecoderOutput("2")])
/// ]
/// XCTAssertNoThrow(try ByteToMessageDecoderVerifier.verifyDecoder(inputOutputPairs: expectedInOuts,
/// decoderFactory: { ExampleDecoder() }))
public static func verifyDecoder<Decoder: ByteToMessageDecoder>(inputOutputPairs: [(ByteBuffer, [Decoder.InboundOut])],
decoderFactory: @escaping () -> Decoder) throws where Decoder.InboundOut: Equatable {
typealias Out = Decoder.InboundOut
func verifySimple(channel: RecordingChannel) throws {
for (input, expectedOutputs) in inputOutputPairs.shuffled() {
try channel.writeInbound(input)
for expectedOutput in expectedOutputs {
guard let actualOutput = try channel.readInbound(as: Out.self) else {
throw VerificationError<Out>(inputs: channel.inboundWrites,
errorCode: .underProduction(expectedOutput))
}
guard actualOutput == expectedOutput else {
throw VerificationError<Out>(inputs: channel.inboundWrites,
errorCode: .wrongProduction(actual: actualOutput,
expected: expectedOutput))
}
}
let actualExtraOutput = try channel.readInbound(as: Out.self)
guard actualExtraOutput == nil else {
throw VerificationError<Out>(inputs: channel.inboundWrites,
errorCode: .overProduction(actualExtraOutput!))
}
}
}
func verifyDripFeed(channel: RecordingChannel) throws {
for _ in 0..<10 {
for (input, expectedOutputs) in inputOutputPairs.shuffled() {
for c in input.readableBytesView {
var buffer = channel.allocator.buffer(capacity: 12)
buffer.writeString("BEFORE")
buffer.writeInteger(c)
buffer.writeString("AFTER")
buffer.moveReaderIndex(forwardBy: 6)
buffer.moveWriterIndex(to: buffer.readerIndex + 1)
try channel.writeInbound(buffer)
}
for expectedOutput in expectedOutputs {
guard let actualOutput = try channel.readInbound(as: Out.self) else {
throw VerificationError<Out>(inputs: channel.inboundWrites,
errorCode: .underProduction(expectedOutput))
}
guard actualOutput == expectedOutput else {
throw VerificationError<Out>(inputs: channel.inboundWrites,
errorCode: .wrongProduction(actual: actualOutput,
expected: expectedOutput))
}
}
let actualExtraOutput = try channel.readInbound(as: Out.self)
guard actualExtraOutput == nil else {
throw VerificationError<Out>(inputs: channel.inboundWrites,
errorCode: .overProduction(actualExtraOutput!))
}
}
}
}
func verifyManyAtOnce(channel: RecordingChannel) throws {
var overallBuffer = channel.allocator.buffer(capacity: 1024)
var overallExpecteds: [Out] = []
for _ in 0..<10 {
for (var input, expectedOutputs) in inputOutputPairs.shuffled() {
overallBuffer.writeBuffer(&input)
overallExpecteds.append(contentsOf: expectedOutputs)
}
}
try channel.writeInbound(overallBuffer)
for expectedOutput in overallExpecteds {
guard let actualOutput = try channel.readInbound(as: Out.self) else {
throw VerificationError<Out>(inputs: channel.inboundWrites,
errorCode: .underProduction(expectedOutput))
}
guard actualOutput == expectedOutput else {
throw VerificationError<Out>(inputs: channel.inboundWrites,
errorCode: .wrongProduction(actual: actualOutput,
expected: expectedOutput))
}
}
}
let decoder: Decoder = decoderFactory()
let channel = RecordingChannel(EmbeddedChannel(handler: ByteToMessageHandler<Decoder>(decoder)))
try verifySimple(channel: channel)
try verifyDripFeed(channel: channel)
try verifyManyAtOnce(channel: channel)
if case .leftOvers(inbound: let ib, outbound: let ob, pendingOutbound: let pob) = try channel.finish() {
throw VerificationError<Out>(inputs: channel.inboundWrites,
errorCode: .leftOversOnDeconstructingChannel(inbound: ib,
outbound: ob,
pendingOutbound: pob))
}
}
}
extension ByteToMessageDecoderVerifier {
private class RecordingChannel {
private let actualChannel: EmbeddedChannel
private(set) var inboundWrites: [ByteBuffer] = []
init(_ actualChannel: EmbeddedChannel) {
self.actualChannel = actualChannel
}
func readInbound<T>(as type: T.Type = T.self) throws -> T? {
return try self.actualChannel.readInbound()
}
@discardableResult public func writeInbound(_ data: ByteBuffer) throws -> EmbeddedChannel.BufferState {
self.inboundWrites.append(data)
return try self.actualChannel.writeInbound(data)
}
var allocator: ByteBufferAllocator {
return self.actualChannel.allocator
}
func finish() throws -> EmbeddedChannel.LeftOverState {
return try self.actualChannel.finish()
}
}
}
extension ByteToMessageDecoderVerifier {
/// A `VerificationError` is thrown when the verification of a `ByteToMessageDecoder` failed.
public struct VerificationError<OutputType: Equatable>: Error {
/// Contains the `inputs` that were passed to the `ByteToMessageDecoder` at the point where it failed
/// verification.
public var inputs: [ByteBuffer]
/// `errorCode` describes the concrete problem that was detected.
public var errorCode: ErrorCode
public enum ErrorCode {
/// The `errorCode` will be `wrongProduction` when the `expected` output didn't match the `actual`
/// output.
case wrongProduction(actual: OutputType, expected: OutputType)
/// The `errorCode` will be set to `overProduction` when a decoding result was yielded where
/// nothing was expected.
case overProduction(OutputType)
/// The `errorCode` will be set to `underProduction` when a decoder didn't yield output when output was
/// expected. The expected output is delivered as the associated value.
case underProduction(OutputType)
/// The `errorCode` will be set to `leftOversOnDeconstructionChannel` if there were left-over items
/// in the `Channel` on deconstruction. This usually means that your `ByteToMessageDecoder` did not process
/// certain items.
case leftOversOnDeconstructingChannel(inbound: [NIOAny], outbound: [NIOAny], pendingOutbound: [NIOAny])
}
}
}
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