A .NET implementation of the Ruby consumer driven contract library, Pact.
Pact is based off the specification found at https://github.com/bethesque/pact_specification.
PactNet primarily provides a fluent .NET DSL for describing HTTP requests that will be made to a service provider and the HTTP responses the consumer expects back to function correctly.
In documenting the consumer interactions, we can replay them on the provider and ensure the provider responds as expected. This basically gives us complete test symmetry and removes the basic need for integrated tests.
PactNet also has the ability to support other mock providers should we see fit.
PactNet is aiming to be Pact Specification Version 1 compliant (Version 2 is a WIP).
From the [Pact Specification repo] (https://github.com/bethesque/pact_specification)
"Pact" is an implementation of "consumer driven contract" testing that allows mocking of responses in the consumer codebase, and verification of the interactions in the provider codebase. The initial implementation was written in Ruby for Rack apps, however a consumer and provider may be implemented in different programming languages, so the "mocking" and the "verifying" steps would be best supported by libraries in their respective project's native languages. Given that the pact file is written in JSON, it should be straightforward to implement a pact library in any language, however, to get the best experience and most reliability of out mixing pact libraries, the matching logic for the requests and responses needs to be identical. There is little confidence to be gained in having your pacts "pass" if the logic used to verify a "pass" is inconsistent between implementations.
Read more about Pact and the problems it solves at https://github.com/realestate-com-au/pact
Please also note that this project is still a work in progress, so there will likely be bugs and items that have not yet been implemented.
Please feel free to contribute, we do accept pull requests.
Below are some samples of usage.
We have also written some //NOTE: comments inline in the code to help explain what certains calls do.
Which may look something like this.
public class SomethingApiClient
{
public string BaseUri { get; set; }
public SomethingApiClient(string baseUri = null)
{
BaseUri = baseUri ?? "http://my-api";
}
public Something GetSomething(string id)
{
string reasonPhrase;
using (var client = new HttpClient { BaseAddress = new Uri(BaseUri) })
{
var request = new HttpRequestMessage(HttpMethod.Get, "/somethings/" + id);
request.Headers.Add("Accept", "application/json");
var response = client.SendAsync(request);
var content = response.Result.Content.ReadAsStringAsync().Result;
var status = response.Result.StatusCode;
reasonPhrase = response.Result.ReasonPhrase; //NOTE: any Pact mock provider errors will be returned here and in the response body
request.Dispose();
response.Dispose();
if (status == HttpStatusCode.OK)
{
return !String.IsNullOrEmpty(content) ?
JsonConvert.DeserializeObject<Something>(content)
: null;
}
}
throw new Exception(reasonPhrase);
}
}Create a new test case within your service consumer test project, using whatever test framework you like (in this case we used xUnit).
This should only be instantiated once for the consumer you are testing.
public class ConsumerMyApiPact : IDisposable
{
public IPactBuilder PactBuilder { get; private set; }
public IMockProviderService MockProviderService { get; private set; }
public int MockServerPort { get { return 1234; } }
public string MockProviderServiceBaseUri { get { return String.Format("http://localhost:{0}", MockServerPort); } }
public ConsumerMyApiPact()
{
PactBuilder = new PactBuilder()
.ServiceConsumer("Consumer")
.HasPactWith("Something API");
MockProviderService = PactBuilder.MockService(MockServerPort); //Configure the http mock server
}
public void Dispose()
{
PactBuilder.Build(); //NOTE: Will save the pact file once finished
}
}
public class SomethingApiConsumerTests : IUseFixture<ConsumerMyApiPact>
{
private IMockProviderService _mockProviderService;
private string _mockProviderServiceBaseUri;
public void SetFixture(ConsumerMyApiPact data)
{
_mockProviderService = data.MockProviderService;
_mockProviderServiceBaseUri = data.MockProviderServiceBaseUri;
data.MockProviderService.ClearInteractions(); //NOTE: Clears any previously registered interactions before the test is run
}
}Create a new test case and implement it.
public class SomethingApiConsumerTests : IUseFixture<ConsumerMyApiPact>
{
private IMockProviderService _mockProviderService;
private string _mockProviderServiceBaseUri;
public void SetFixture(ConsumerMyApiPact data)
{
_mockProviderService = data.MockProviderService;
_mockProviderServiceBaseUri = data.MockProviderServiceBaseUri;
data.MockProviderService.ClearInteractions(); //NOTE: Clears any previously registered interactions before the test is run
}
[Fact]
public void GetSomething_WhenTheTesterSomethingExists_ReturnsTheSomething()
{
//Arrange
_mockProviderService
.Given("There is a something with id 'tester'")
.UponReceiving("A GET request to retrieve the something")
.With(new ProviderServiceRequest
{
Method = HttpVerb.Get,
Path = "/somethings/tester",
Headers = new Dictionary<string, string>
{
{ "Accept", "application/json" }
}
})
.WillRespondWith(new ProviderServiceResponse
{
Status = 200,
Headers = new Dictionary<string, string>
{
{ "Content-Type", "application/json; charset=utf-8" }
},
Body = new //NOTE: Note the case sensitivity here, the body will be serialised as per the casing defined
{
id = "tester",
firstName = "Totally",
lastName = "Awesome"
}
}); //NOTE: WillRespondWith call must come last as it will register the interaction
var consumer = new SomethingApiClient(_mockProviderServiceBaseUri);
//Act
var result = consumer.GetSomething("tester");
//Assert
Assert.Equal("tester", result.id);
_mockProviderService.VerifyInteractions(); //NOTE: Verifies that interactions registered on the mock provider are called once and only once
}
}Everything should be green
Note: we advise using a TDD approach when using this library, however we will leave it up to you.
Likely you will be creating a skeleton client, describing the pact, write the failing test, implement the skeleton client, run the test to make sure it passes, then rinse and repeat.
You can create the API using whatever framework you like, however we recommend using ASP.NET Web API 2 with Owin as it allows you to use the Microsoft.Owin.Testing Nuget package.
Using the Microsoft.Owin.Testing package allows you to create an in memory version of your API to test against, which removes the pain of deployment and configuration when running the tests.
Create a new test case within your service provider test project, using whatever test framework you like (in this case we used xUnit).
a) If using an Owin compatible API, like ASP.NET Web API 2 and using the Microsoft.Owin.Testing Nuget package (preferred)
public class SomethingApiTests
{
[Fact]
public void EnsureSomethingApiHonoursPactWithConsumer()
{
//Arrange
var pactVerifier = new PactVerifier();
pactVerifier
.ProviderStatesFor("Consumer") //NOTE: You can supply setUp and tearDown, which will run before starting and after completing the verifications.
.ProviderState("There is a something with id 'tester'",
setUp: AddTesterIfItDoesntExist); //NOTE: We also have tearDown
//Act / Assert
using (var testServer = TestServer.Create<Startup>()) //NOTE: This is using the Microsoft.Owin.Testing nuget package
{
pactVerifier
.ServiceProvider("Something API", testServer.HttpClient)
.HonoursPactWith("Consumer")
.PactUri("../../../Consumer.Tests/pacts/consumer-something_api.json")
.Verify(); //NOTE: Optionally you can control what interactions are verified by specifying a providerDescription and/or providerState
}
}
private void AddTesterIfItDoesntExist()
{
//Logic to add the 'tester' something
}
}or
b) If using a non Owin compatible API, you can provide your own HttpClient and point to the deployed API.
public class SomethingApiTests
{
[Fact]
public void EnsureSomethingApiHonoursPactWithConsumer()
{
//Arrange
var pactVerifier = new PactVerifier();
pactVerifier
.ProviderStatesFor("Consumer") //NOTE: You can supply setUp and tearDown, which will run before starting and after completing the verifications.
.ProviderState("There is a something with id 'tester'",
setUp: AddTesterIfItDoesntExist); //NOTE: We also have tearDown
//Act / Assert
using (var client = new HttpClient { BaseAddress = new Uri("http://api-address:9999") })
{
pactVerifier
.ServiceProvider("Something API", client)
.HonoursPactWith("Consumer")
.PactUri("../../../Consumer.Tests/pacts/consumer-something_api.json")
.Verify(); //NOTE: Optionally you can control what interactions are verified by specifying a providerDescription and/or providerState
}
}
private void AddTesterIfItDoesntExist()
{
//Logic to add the 'tester' something
}
}Everything should be green
Again, please note: we advise using a TDD approach when using this library, however we will leave it up to you.
For further examples please refer to the Samples in the solution.