8-Oct-2009
Unit testing a class that has a dependency on a external service, can be annoying. The last thing you want to do is send live calls. The other options appear to be setting up a test service with a test database, or writing an Echo style service that simply accepts any incoming data and echoes it back. Neither of these are cool, and require far too much work and plumbing (not to mention slow). The ideal would seem to be the ability to quickly configure and run up a mock http listener to receive requests and give back programmable responses all isolated to the test.
I stumbled across a partial solution here: http://weblogs.asp.net/pglavich/archive/2005/09/04/424392.aspx
I customised, and perhaps simplified for my use case to this: (apologies for the bad copy and paste of my IDE style)
Start at the start, the TestMethod:
[TestMethod]
public void SendNotificationTest() {
var mockService = new MockRestService();
var subjectUnderTest = new SendNotificationJob() {
Identity = GetTestData(Guid.NewGuid(), CreateUniqueLogOnId()),
Url = new Uri(mockService.ListenOnUrl + "TestMethodName")
};
mockService.StartAsync();
subjectUnderTest.SendNotification();
mockService.Stop();
Assert.IsTrue(mockService.RequestUrlsReceived.Count == 1);
Assert.AreEqual(mockService.ListenOnUrl + "TestMethodName", mockService.RequestUrlsReceived[0]);
}
Secondly the MockRestService class:
using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Threading;
public class MockRestService {
private readonly HttpListener testServer;
private bool keepListening = true;
private Thread listeningThread;
public MockRestService() {
string uniqueServiceName = Guid.NewGuid().ToString().Replace("-", string.Empty);
string serviceUrl = "http://localhost:60340/" + uniqueServiceName + "/";
this.testServer = new HttpListener();
this.testServer.Prefixes.Add(serviceUrl);
this.ListenOnUrl = new Uri(serviceUrl);
this.testServer.Start();
this.ResponsesToReturn = new Queue<string>();
this.StatusesToReturn = new Queue<HttpStatusCode>();
this.RequestUrlsReceived = new List<string>();
}
public Uri ListenOnUrl { get; private set; }
public IList<string> RequestUrlsReceived { get; private set; }
public Queue<string> ResponsesToReturn { get; private set; }
public Queue<HttpStatusCode> StatusesToReturn { get; private set; }
public void Stop() {
this.keepListening = false;
this.listeningThread.Join();
}
public void StartAsync() {
this.listeningThread = new Thread(() => this.Start());
this.listeningThread.Start();
}
private void Start() {
do {
var context = this.testServer.GetContext();
if (context.Request != null && context.Request.Url != null && !string.IsNullOrEmpty(context.Request.Url.ToString())) {
this.RequestUrlsReceived.Add(context.Request.Url.ToString());
var writer = new StreamWriter(context.Response.OutputStream);
if (this.ResponsesToReturn.Count == 0) {
writer.WriteLine("Ok");
} else {
writer.WriteLine(this.ResponsesToReturn.Dequeue());
}
writer.Close();
if (this.StatusesToReturn.Count == 0) {
context.Response.StatusCode = (int)HttpStatusCode.OK;
} else {
context.Response.StatusCode = (int)this.StatusesToReturn.Dequeue();
}
context.Response.Close();
}
} while (this.keepListening);
}
}
Thats basically the crux of it. If anyone's interested I'll post complete code.
Ben Rees - Oct 25, 2009 12:19 AM
A much tidier revision. Added support for optionally adding headers, and used a event to handle incoming requests.
using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Threading;
using Collections;
/// <summary>
/// A mock to remove dependencies on external REST services. Designed to listen on a Url and Port number using standard Http.
/// </summary>
public sealed class MockRestService : IDisposable {
private readonly HttpListener testServer;
private HttpListenerContext context;
private bool isActive;
private bool keepListening = true;
/// <summary>
/// Initializes a new instance of the <see cref="MockRestService"/> class.
/// </summary>
public MockRestService() {
string uniqueServiceName = Guid.NewGuid().ToString().Replace("-", string.Empty);
string serviceUrl = "http://localhost:60340/" + uniqueServiceName + "/";
this.testServer = new HttpListener();
this.testServer.Prefixes.Add(serviceUrl);
this.ListenOnUrl = new Uri(serviceUrl);
this.testServer.Start();
this.ResponsesToReturn = new EventedQueue<string>();
this.ResponsesToReturn.ItemAdded += (s, e) => {
if (this.isActive) {
throw new InvalidOperationException("You cannot add to the Response Queue after the service has been started.");
}
};
this.StatusesToReturn = new EventedQueue<HttpStatusCode>();
this.StatusesToReturn.ItemAdded += (s, e) => {
if (this.isActive) {
throw new InvalidOperationException("You cannot add to the Status Queue after the service has been started.");
}
};
this.RequestUrlsReceived = new List<string>();
this.ResponseHeaders = new Dictionary<int, KeyValuePair<string, string>>();
}
/// <summary>
/// Gets the URL that has been setup to listen on. The Url is auto-generated to be unique every time this class is instantiated.
/// </summary>
/// <value>The listen on URL.</value>
public Uri ListenOnUrl { get; private set; }
/// <summary>
/// Gets the request urls that have been received. Used to check and assert test case pass.
/// </summary>
/// <value>The request urls received.</value>
public IList<string> RequestUrlsReceived { get; private set; }
/// <summary>
/// Gets the response headers. Keyed by an int zero-based index to indicate which response should be given then header.
/// </summary>
/// <example>
/// To add a header to the second response:
/// using (var serviceMock = new MockRestService) {
/// serviceMock.ResponseHeaders.Add(1, new KeyValuePair("HeaderName", "Some Header content goes in here."));
/// serviceMock.StartAsync();
/// }
/// </example>
/// <value>The response headers.</value>
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures", Justification = "Assessed and is appropriate here")]
public IDictionary<int, KeyValuePair<string, string>> ResponseHeaders { get; private set; }
/// <summary>
/// Gets the responses to return for each request. Responses are given out in queue order.
/// </summary>
/// <value>The responses to return.</value>
public EventedQueue<string> ResponsesToReturn { get; private set; }
/// <summary>
/// Gets the statuses to return. Statuses are given out in queue order.
/// </summary>
/// <value>The statuses to return.</value>
public EventedQueue<HttpStatusCode> StatusesToReturn { get; private set; }
/// <summary>
/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
/// </summary>
public void Dispose() {
this.Dispose(true);
}
/// <summary>
/// Starts the listener. This will spin up a asynchronous thread to listen for incoming requests.
/// </summary>
public void StartAsync() {
this.isActive = true;
this.testServer.BeginGetContext(this.RequestReceived, null);
}
/// <summary>
/// Releases unmanaged and - optionally - managed resources
/// </summary>
/// <param name="cleanUpManaged"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged resources.</param>
public void Dispose(bool cleanUpManaged) {
if (cleanUpManaged) {
this.keepListening = false;
this.isActive = false;
if (this.testServer.IsListening) {
this.testServer.Close();
}
}
}
private void RequestReceived(IAsyncResult result) {
if (!this.keepListening) {
return;
}
this.context = this.testServer.EndGetContext(result);
if (this.context.Request != null && this.context.Request.Url != null && !string.IsNullOrEmpty(this.context.Request.Url.ToString())) {
this.RequestUrlsReceived.Add(this.context.Request.Url.ToString());
int requestNumber = this.RequestUrlsReceived.Count - 1;
var writer = new StreamWriter(this.context.Response.OutputStream);
if (this.ResponsesToReturn.Count == 0) {
writer.WriteLine("Ok");
} else {
writer.WriteLine(this.ResponsesToReturn.Dequeue());
}
if (this.ResponseHeaders.ContainsKey(requestNumber)) {
var header = this.ResponseHeaders[requestNumber];
this.context.Response.AddHeader(header.Key, header.Value);
}
if (this.StatusesToReturn.Count == 0) {
this.context.Response.StatusCode = (int)HttpStatusCode.OK;
} else {
this.context.Response.StatusCode = (int)this.StatusesToReturn.Dequeue();
}
writer.Close();
this.context.Response.Close();
}
if (this.keepListening) { // Could be improved to ensure against race-condition (keepListening may be set to false before all calls can be processed).
this.testServer.BeginGetContext(this.RequestReceived, null);
}
}
}
using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Threading;
using Collections;
/// <summary>
/// A mock to remove dependencies on external REST services. Designed to listen on a Url and Port number using standard Http.
/// </summary>
public sealed class MockRestService : IDisposable {
private readonly HttpListener testServer;
private HttpListenerContext context;
private bool isActive;
private bool keepListening = true;
/// <summary>
/// Initializes a new instance of the <see cref="MockRestService"/> class.
/// </summary>
public MockRestService() {
string uniqueServiceName = Guid.NewGuid().ToString().Replace("-", string.Empty);
string serviceUrl = "http://localhost:60340/" + uniqueServiceName + "/";
this.testServer = new HttpListener();
this.testServer.Prefixes.Add(serviceUrl);
this.ListenOnUrl = new Uri(serviceUrl);
this.testServer.Start();
this.ResponsesToReturn = new EventedQueue<string>();
this.ResponsesToReturn.ItemAdded += (s, e) => {
if (this.isActive) {
throw new InvalidOperationException("You cannot add to the Response Queue after the service has been started.");
}
};
this.StatusesToReturn = new EventedQueue<HttpStatusCode>();
this.StatusesToReturn.ItemAdded += (s, e) => {
if (this.isActive) {
throw new InvalidOperationException("You cannot add to the Status Queue after the service has been started.");
}
};
this.RequestUrlsReceived = new List<string>();
this.ResponseHeaders = new Dictionary<int, KeyValuePair<string, string>>();
}
/// <summary>
/// Gets the URL that has been setup to listen on. The Url is auto-generated to be unique every time this class is instantiated.
/// </summary>
/// <value>The listen on URL.</value>
public Uri ListenOnUrl { get; private set; }
/// <summary>
/// Gets the request urls that have been received. Used to check and assert test case pass.
/// </summary>
/// <value>The request urls received.</value>
public IList<string> RequestUrlsReceived { get; private set; }
/// <summary>
/// Gets the response headers. Keyed by an int zero-based index to indicate which response should be given then header.
/// </summary>
/// <example>
/// To add a header to the second response:
/// using (var serviceMock = new MockRestService) {
/// serviceMock.ResponseHeaders.Add(1, new KeyValuePair("HeaderName", "Some Header content goes in here."));
/// serviceMock.StartAsync();
/// }
/// </example>
/// <value>The response headers.</value>
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures", Justification = "Assessed and is appropriate here")]
public IDictionary<int, KeyValuePair<string, string>> ResponseHeaders { get; private set; }
/// <summary>
/// Gets the responses to return for each request. Responses are given out in queue order.
/// </summary>
/// <value>The responses to return.</value>
public EventedQueue<string> ResponsesToReturn { get; private set; }
/// <summary>
/// Gets the statuses to return. Statuses are given out in queue order.
/// </summary>
/// <value>The statuses to return.</value>
public EventedQueue<HttpStatusCode> StatusesToReturn { get; private set; }
/// <summary>
/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
/// </summary>
public void Dispose() {
this.Dispose(true);
}
/// <summary>
/// Starts the listener. This will spin up a asynchronous thread to listen for incoming requests.
/// </summary>
public void StartAsync() {
this.isActive = true;
this.testServer.BeginGetContext(this.RequestReceived, null);
}
/// <summary>
/// Releases unmanaged and - optionally - managed resources
/// </summary>
/// <param name="cleanUpManaged"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged resources.</param>
public void Dispose(bool cleanUpManaged) {
if (cleanUpManaged) {
this.keepListening = false;
this.isActive = false;
if (this.testServer.IsListening) {
this.testServer.Close();
}
}
}
private void RequestReceived(IAsyncResult result) {
if (!this.keepListening) {
return;
}
this.context = this.testServer.EndGetContext(result);
if (this.context.Request != null && this.context.Request.Url != null && !string.IsNullOrEmpty(this.context.Request.Url.ToString())) {
this.RequestUrlsReceived.Add(this.context.Request.Url.ToString());
int requestNumber = this.RequestUrlsReceived.Count - 1;
var writer = new StreamWriter(this.context.Response.OutputStream);
if (this.ResponsesToReturn.Count == 0) {
writer.WriteLine("Ok");
} else {
writer.WriteLine(this.ResponsesToReturn.Dequeue());
}
if (this.ResponseHeaders.ContainsKey(requestNumber)) {
var header = this.ResponseHeaders[requestNumber];
this.context.Response.AddHeader(header.Key, header.Value);
}
if (this.StatusesToReturn.Count == 0) {
this.context.Response.StatusCode = (int)HttpStatusCode.OK;
} else {
this.context.Response.StatusCode = (int)this.StatusesToReturn.Dequeue();
}
writer.Close();
this.context.Response.Close();
}
if (this.keepListening) { // Could be improved to ensure against race-condition (keepListening may be set to false before all calls can be processed).
this.testServer.BeginGetContext(this.RequestReceived, null);
}
}
}
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