XCRemoteCache/Tests/XCRemoteCacheTests/Network/NetworkClientImplTests.swift

// Copyright (c) 2021 Spotify AB.
//
// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you 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
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// 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.

@testable import XCRemoteCache
import XCTest

class NetworkClientImplTests: XCTestCase {
    typealias Completion<R> = (Result<R, NetworkClientError>) -> Void

    private var responses: [URL: URLProtocolStub.Response] {
        get {
            URLProtocolStub.responses
        }
        set {
            URLProtocolStub.responses = newValue
        }
    }

    private var requests: [URLRequest] {
        get {
            URLProtocolStub.requests
        }
        set {
            URLProtocolStub.requests = newValue
        }
    }

    private let successStatus = 200
    private let failureStatus = 400
    private var url: URL!
    private var successResponse: URLResponse!
    private var failureResponse: URLResponse!
    private var session: URLSession!
    private let fileURL = URL(fileURLWithPath: "/sample")
    private var fileManager: FileManager!
    private var client: NetworkClientImpl!

    override func setUpWithError() throws {
        try super.setUpWithError()
        responses = [:]
        requests = []
        url = try URL(string: "http://example.com").unwrap()
        successResponse = try HTTPURLResponse(
            url: url,
            statusCode: successStatus,
            httpVersion: nil,
            headerFields: nil
        ).unwrap()
        failureResponse = try HTTPURLResponse(
            url: url,
            statusCode: failureStatus,
            httpVersion: nil,
            headerFields: nil
        ).unwrap()
        let configuration = URLSessionConfiguration.ephemeral
        configuration.protocolClasses = [URLProtocolStub.self]
        session = URLSession(configuration: configuration)
        fileManager = FileManager.default
        client = NetworkClientImpl(
            session: session,
            retries: 0,
            retryDelay: 0,
            fileManager: fileManager,
            awsV4Signature: nil
        )
    }

    override func tearDown() {
        url = nil
        successResponse = nil
        failureResponse = nil
        client = nil
        session = nil
        fileManager = nil
        requests = []
        responses = [:]
        super.tearDown()
    }

    func waitForResponse<R>(_ action: (@escaping Completion<R>) -> Void, timeout: TimeInterval = 0.1) throws -> Result<R, NetworkClientError> {
        let responseExpectation = expectation(description: "RequestResponse")
        var receivedResponse: Result<R, NetworkClientError>?

        action { response in
            receivedResponse = response
            responseExpectation.fulfill()
        }
        waitForExpectations(timeout: timeout)
        return try receivedResponse.unwrap()
    }

    func testFetch400CompletesWithFailure() throws {
        responses[url] = .success(failureResponse, Data())
        let response = try waitForResponse { client.fetch(url, completion: $0) }

        guard case .failure(.unsuccessfulResponse(failureStatus)) = response else {
            XCTFail("Unexpected response \(response).")
            return
        }
    }

    func testFetch200CompletesWithSuccess() throws {
        responses[url] = .success(successResponse, Data())
        let response = try waitForResponse { client.fetch(url, completion: $0) }

        guard case .success(Data()) = response else {
            XCTFail("Unexpected response \(response).")
            return
        }
    }

    func testUpload200CompletesWithSuccess() throws {
        let fileURL = URL(fileURLWithPath: "/sample")
        responses[url] = .success(successResponse, Data())
        let response = try waitForResponse { client.upload(fileURL, as: url, completion: $0) }

        guard case .success(()) = response else {
            XCTFail("Unexpected response \(response).")
            return
        }
    }

    func testUpload400CompletesWithFailure() throws {
        responses[url] = .success(failureResponse, Data())
        let response = try waitForResponse { client.upload(fileURL, as: url, completion: $0) }

        guard case .failure(.unsuccessfulResponse(failureStatus)) = response else {
            XCTFail("Unexpected response \(response).")
            return
        }
    }

    func testUploadFilureWith400Retries() throws {
        client = NetworkClientImpl(
            session: session,
            retries: 2,
            retryDelay: 0,
            fileManager: fileManager,
            awsV4Signature: nil
        )
        responses[url] = .success(failureResponse, Data())
        _ = try waitForResponse({ client.upload(fileURL, as: url, completion: $0) }, timeout: 0.5)

        XCTAssertEqual(
            requests.map(\.url),
            Array(repeating: url, count: 3),
            "Expected 3 requests (original + 2 retries)"
        )
    }

    func testUploadSuccessDoesntRetry() throws {
        client = NetworkClientImpl(
            session: session,
            retries: 2,
            retryDelay: 0,
            fileManager: fileManager,
            awsV4Signature: nil
        )
        responses[url] = .success(successResponse, Data())
        _ = try waitForResponse { client.upload(fileURL, as: url, completion: $0) }

        XCTAssertEqual(requests.map(\.url), [url], "Expected 1 request - original only")
    }

    func testDownloadFilureWith400Retries() throws {
        client = NetworkClientImpl(
            session: session,
            retries: 2,
            retryDelay: 0,
            fileManager: fileManager,
            awsV4Signature: nil
        )
        responses[url] = nil
        _ = try waitForResponse({ client.download(url, to: fileURL, completion: $0) }, timeout: 0.5)

        XCTAssertEqual(
            requests.map(\.url),
            Array(repeating: url, count: 3),
            "Expected 3 requests (original + 2 retries)"
        )
    }

    func testDownloadSuccessDoesntRetry() throws {
        client = NetworkClientImpl(
            session: session,
            retries: 2,
            retryDelay: 0,
            fileManager: fileManager,
            awsV4Signature: nil
        )
        responses[url] = .success(successResponse, Data())
        _ = try waitForResponse { client.download(url, to: fileURL, completion: $0) }

        XCTAssertEqual(requests.map(\.url), [url], "Expected 1 request - original only")
    }

    func testFileExits400CompletesWithFalse() throws {
        responses[url] = .success(failureResponse, Data())
        let response = try waitForResponse { client.fileExists(url, completion: $0) }

        guard case .success(false) = response else {
            XCTFail("Unexpected response \(response).")
            return
        }
    }

    func testFileExits200CompletesWithTrue() throws {
        responses[url] = .success(successResponse, Data())
        let response = try waitForResponse { client.fileExists(url, completion: $0) }

        guard case .success(true) = response else {
            XCTFail("Unexpected response \(response).")
            return
        }
    }

    func testFileExitsErrorCompletesWithFailure() throws {
        let response = try waitForResponse { client.fileExists(url, completion: $0) }

        guard case .failure(.other) = response else {
            XCTFail("Unexpected response \(response).")
            return
        }
    }

    func testDownloadTimeoutReportsTimeoutError() throws {
        responses[url] = .timeout
        let response = try waitForResponse { client.fileExists(url, completion: $0) }

        guard case .failure(.timeout) = response else {
            XCTFail("Unexpected response \(response).")
            return
        }
    }

    func testAWSV4SignatureHeader() throws {
        let signature = AWSV4Signature(
            secretKey: "wJalrXUtnFEMI/K7MDENG+bPxRfiCYEXAMPLEKEY",
            accessKey: "AKIDEXAMPLE",
            securityToken: "IQoJb3JpZ2luX2VjENv//////////wEaCXVzLWVhc3Q+bsHwqnovXtl/1JVe61XHMnAw3AIXwOAOxqMvhw==",
            region: "us-east-1",
            service: "iam",
            date: Date(timeIntervalSince1970: 1_440_938_160)
        )
        client = NetworkClientImpl(
            session: session,
            retries: 0,
            retryDelay: 0,
            fileManager: fileManager,
            awsV4Signature: signature
        )
        responses[url] = .success(successResponse, Data())
        _ = try waitForResponse { client.fetch(url, completion: $0) }

        XCTAssertEqual(
            "AWS4-HMAC-SHA256 Credential=AKIDEXAMPLE/20150830/us-east-1/iam/aws4_request, " +
                "SignedHeaders=host;x-amz-content-sha256;x-amz-date;x-amz-security-token, " +
                "Signature=e5578464567fb97fd26e871702e4ec4ff7d61cb87eb72a40d22b80e12da30c34",
            try requests[0].allHTTPHeaderFields?["Authorization"].unwrap()
        )
    }
}