Wiremock

Chapter I: The Basics



WireMock is a library for stubbing and mocking web services. It constructs an HTTP server that we could connect to as we would to an actual web service.

    com.github.tomakehurst
    wiremock
    ${wiremock.latest}
    test

  • Simulator/MockServer for HTTP-based APIs
  • Stay productive when an API you depend on doesn't exist
  • Testing of edge cases and failures that the real API won't reliably produce

Flexible Deployment

Run WireMock from within a

  • Java Application
  • JUnit Test
  • Servlet Container
  • Standalone Process

Powerful Request Matching

Matches…

  • Request URLs
  • Methods
  • Headers
  • Cookies
  • Bodies

…using a wide variety of strategies.

First class support for JSON and XML.

Record and Playback

Get up and running quickly by capturing traffic to and from an existing API.

Ok, Leonidas !
Let's have a look…

Components of shown Example

@Test
public void testPositive() {
	//arrange
	stubFor(get(urlEqualTo("/game/info/difficulty"))
			.willReturn(aResponse()
					.withStatus(HttpStatus.SC_OK)
					.withHeader(HttpHeaders.CONTENT_TYPE, MediaType.TEXT_PLAIN)
					.withBody(Difficulty.OVER9000.name())));

	//act
	Response result = restResourceUnderTest.loadCurrentDifficulty();

	//assert
	assertThat(result.getStatus()).isEqualTo(HttpStatus.SC_OK);
	assertThat(result.readEntity(String.class)).contains("OVER9000");
	…
}
Arrange Setup your REST-Service implementation simulated by Wiremock.
Act REST-Client calls simulated Service implementation.
Assert Do your assertions for call meta-information, data-integrity, etc.

Delays

stubFor(get(urlEqualTo("/delayed")).willReturn(
        aResponse()
                .withStatus(200)
                .withFixedDelay(2000)));

Delays can be configured as follows:

.withFixedDelay() all responses are delayed by x milliseconds
.withUniformRandomDelay() all responses are delayed randomly using a uniform distribution
.withLogNormalRandomDelay() all responses are delayed randomly using a log-normal distribution

Bad responses

stubFor(get(urlEqualTo("/fault"))
	.willReturn(aResponse()
		.withFault(Fault.MALFORMED_RESPONSE_CHUNK)));

The Fault.java enum has the following options:

EMPTY_RESPONSE Returns a completely empty response.
RANDOM_DATA_THEN_CLOSE Sends random data, then closes the connection.
MALFORMED_RESPONSE_CHUNK Sends an OK (200) status header, then garbage 💩, then closes the connection. 
keytool -genkey -keyalg RSA -alias selfsigned -keystore keystore.jks -storepass password -validity 360 -keysize 2048
  • What is your first and last name ?
    • Common Name (CN) -> localhost
  • What is the name of your organizational unit ?
    • Organizational Unit (OU) -> …
  • What is the name of your organization ?
    • Organization (O) -> …
  • What is the name of your City or Locality ?
    • Locality (L) -> …
  • What is the name of your State or Province ?
    • State (ST) -> …
  • What is the two-letter country code for this unit ?
    • Country (C) -> DE 
@Rule
public WireMockRule wireMock = new WireMockRule(wireMockConfig()
		.dynamicHttpsPort()
		.keystorePath("src/test/resources/wiremock.jks")
		.keystorePassword("password"));

private static final String BASE_URL = "https://localhost:";

To use SSL during testing the WireMockRule needs a config with:

.dynamicHttpsPort() Configures WireMock to allocate an https port.
.keystorePath() The path to the keystore that stores your certificate
.keystorePassword() Your companies intranet password 🙈

There's even more!

Chapter II - Advanced Testing

Request-Matching How to build a better stub
JSON/XML Data Bodies Work with more complex bodies
Verification Verify correct behaviour of your code

Do you have any…

Fin

Andre Kramer - Tobias Spindler