Mastering WireMock for Effective API Testing

Explore how WireMock, a powerful HTTP API mocking framework, enables stubbing, request matching, response configuration, and delay or fault simulation to test and develop apps that rely on third-party APIs.

Discover how wire mock's standalone or embedded server uses stub configurations and matching rules to intercept requests and return customized responses, removing dependency on the Twitter API.

Identify the essential tools for this course, including the Java development kit, Maven, IntelliJ IDE, and Postman. Use the same tool versions shown to avoid configuration issues.

Download and install 64-bit OpenJDK, set the Javahome system variable, update the path variable, restart prompts, and verify the installation with java -version.

Configure Apache Maven on your local system by downloading the Apache Maven binary, unzipping it, setting the mvn home system variable, updating the path, and verifying with a command.

Download the JetBrains IntelliJ IDEA community edition 2024.3.5 from the official website. Unzip the zip file, then launch the ide64 executable from the bin directory to complete the setup.

Install Postman locally by downloading the installer from the official website, set up the tool on your system, and send a request to view the response and status code.

Create a Java project in IntelliJ using the Maven quickstart archetype, configure JDK 21, and add wire mock and JUnit dependencies plus a fluent HTTP client.

Learn how to set up Bruno on your local system, install with default settings, and use Bruno or Postman to interact with the test application for this course.

Explore how WireMock integrates with Java and supports API testing. Learn to pair WireMock with a Java based unit testing framework, specifically JUnit, to enable effective API testing.

Explore the JUnit framework for Java unit testing, covering annotations for test methods, setup and teardown, assertions, and test runners, plus Maven or Gradle integration and the standard test lifecycle.

Use JUnit to write unit tests for a Java calculator in project configured with pom.xml, with src main Java and src test Java, and before/after hooks plus display name options.

Learn to validate test results using JUnit assertions, including assertEquals and assertTrue, with static imports and custom error messages for reliable test feedback.

Explore extensions in the JUnit framework to customize test behavior with callback interfaces, focusing on the first four of seven, with a practical next video demo.

Explore creating and using a custom JUnit extension to print test method names and access extension APIs via extend with and register extension, demonstrated in a calculator test.

Explore how the fluent http client wraps the Apache http client to write readable, builder-pattern tests for APIs, including sending requests, adding headers, and validating status codes.

Start the WireMock server as a standalone process by downloading the standalone jar from Maven and running java -jar, optionally on a custom port with --port.

Learn to run a WireMock server as an embedded test server, start and stop it programmatically, configure ports, and optimize tests with before all and after all.

Explore how HTTP methods align with CRUD, including GET, POST, PUT, PATCH, and DELETE, and see how to mock these requests using a mocking tool.

Understand the structure of HTTP requests and responses, including the request line with method, URL, and version, headers, and optional body, and the response with status line, headers, and body.

Explore the watermark learning approach with a sample server that supports crud and a client library that abstracts the http layer, guided by test driven development and wireshark-based wire mock.

Design a four-layer library architecture for api testing, detailing interaction, data transformation, communication, and validation layers. Use a fluent http client to communicate with the server or mock instance.

Create a new library module with Maven quickstart, set JDK 21, and establish a modular structure: communication, validation, transform, and models, configuring JUnit and fluent http client dependencies.

Design the communication layer for wiremock using an abstraction with a communication interface for get, post, put, patch, and delete, with a concrete class implementing it; favor abstraction for flexibility.

Develop a communication layer with a create API and a get all API returning fluent client responses, plus a builder-based config for URL and content type and a concrete implementation.

Start Micronaut app with Java -jar, set a port with Micronaut server port, and use swagger UI to test add pet (json/xml) and get all pets via Bruno or Postman.

Structure a test class for the communication layer to verify the get all endpoint using before all and after all hooks, with a builder-based configuration for the base url.

Explore WireMock's stub configuration by using the mapping builder, request pattern, and response definition to register stub mappings that simulate server responses for matched HTTP requests.

Master API testing with WireMock by configuring a 204 no content response for a get request, using accept headers, content-type, and stub management to validate responses.

Learn to enhance WireMock stubs by attaching a custom response header using with header and with headers. Verify the header in the response to simulate real-world api behavior.

Configure a WireMock stub to return a custom response body in multiple formats (base64, JSON node, bytes, string) and validate a 200 ok response with assertions.

Master verifying the custom response contents in wiremock by extracting the http entity, reading the input stream, and validating the json payload with assertj.