NetNewsWire/Frameworks/Account/AccountTests/TestTransport.swift

//
//  TestTransport.swift
//  AccountTests
//
//  Created by Maurice Parker on 5/4/19.
//  Copyright © 2019 Ranchero Software, LLC. All rights reserved.
//

import Foundation
import RSWeb
import XCTest

protocol TestTransportMockResponseProviding: class {
	func mockResponseFileUrl(for components: URLComponents) -> URL?
}

final class TestTransport: Transport {
	
	enum TestTransportError: String, Error {
		case invalidState = "The test wasn't set up correctly."
	}
	
	var testFiles = [String: String]()
	var testStatusCodes = [String: Int]()
	
	weak var mockResponseFileUrlProvider: TestTransportMockResponseProviding?
	
	private func httpResponse(for request: URLRequest, statusCode: Int = 200) -> HTTPURLResponse {
		guard let url = request.url else {
			fatalError("Attempting to mock a http response for a request without a URL \(request).")
		}
		return HTTPURLResponse(url: url, statusCode: statusCode, httpVersion: "HTTP/1.1", headerFields: nil)!
	}
	
	func cancelAll() { }
	
	func send(request: URLRequest, completion: @escaping (Result<(HTTPURLResponse, Data?), Error>) -> Void) {
		
		guard let url = request.url, let components = URLComponents(url: url, resolvingAgainstBaseURL: false) else {
			completion(.failure(TestTransportError.invalidState))
			return
		}
		
		let urlString = url.absoluteString
		let response = httpResponse(for: request, statusCode: testStatusCodes[urlString] ?? 200)
		let testFileURL: URL
		
		if let provider = mockResponseFileUrlProvider {
			guard let providerUrl = provider.mockResponseFileUrl(for: components) else {
				XCTFail("Test behaviour undefined. Mock provider failed to provide non-nil URL for \(components).")
				return
			}
			testFileURL = providerUrl
			
		} else if let testKeyAndFileName = testFiles.first(where: { urlString.contains($0.key) }) {
			testFileURL = Bundle(for: TestTransport.self).resourceURL!.appendingPathComponent(testKeyAndFileName.value)
			
		} else {
			// XCTFail("Missing mock response for: \(urlString)")
			print("***\nWARNING: \(self) missing mock response for:\n\(urlString)\n***")
			DispatchQueue.global(qos: .background).async {
				completion(.success((response, nil)))
			}
			return
		}
		
		do {
			let data = try Data(contentsOf: testFileURL)
			DispatchQueue.global(qos: .background).async {
				completion(.success((response, data)))
			}
		} catch {
			XCTFail("Unable to read file at \(testFileURL) because \(error).")
			DispatchQueue.global(qos: .background).async {
				completion(.failure(error))
			}
		}
	}

	func send(request: URLRequest, method: String, completion: @escaping (Result<Void, Error>) -> Void) {
		fatalError("Unimplemented.")
	}
	
	func send(request: URLRequest, method: String, payload: Data, completion: @escaping (Result<(HTTPURLResponse, Data?), Error>) -> Void) {
		fatalError("Unimplemented.")
	}
}