Workshop on Consumer-Driven Contracts

This repository points to some material that can be used in a hands-on workshop to get a feel for Consumer-Driven Contracts with the frameworks Pact and / or Spring Cloud Contract.

Preparation

If you're new to Consumer-Driven Contracts, read this article as an introduction to CDC.

The setup takes some time since dependencies have to be loaded from the internet. So it makes sense to follow these steps in advance:

• make sure you have Java 8 installed
• for the Angular example, make sure you have the latest NodeJS installed
• clone this repository

1. REST Contracts

Task #1: Define a REST contract

In a group of 2-3, dream up a use case and define a contract between a REST consumer and a REST provider.

The contract should consist of 2-3 interactions (request / response pairs).

Per interaction, define

• the path of the request
• the HTTP method of the request
• potential request headers
• potential query parameters in the request
• the JSON structure of the request body
• the JSON structure of the response body
• the HTTP status code of the response
• potential response headers.

Write down the definition in a text file or on paper for later reference.

REST Contracts with Java

Task #2: Implement a REST Consumer with Spring, Feign & Pact

1. Start with the code in the folder consumer/pact-feign-consumer
2. Go through the steps explained in this tutorial to set up a consumer test that creates a pact file
   • use one interaction of the API you defined in Task #1 instead of the API described in the tutorial
   • choose different consumer and provider names to make your implementation unique
3. If you need orientation, have a look at the complete example
4. Run ./gradlew build to run the tests and check that a pact file has been created in the folder target/pacts

Task #3: Implement a REST Provider with Spring & Pact

1. Start with the code in the folder provider/pact-spring-provider
2. Go through the steps explained in this tutorial to set up a Spring REST Controller that satisfies the contract from Task #1
3. If you need orientation, have a look at the complete example
4. Run ./gradlew build to run the provider test and check that it works

Task #4: Implement a REST Consumer & Provider with Spring Cloud Contract

1. Start with the code in the folders consumer/scc-consumer and provider/scc-provider
2. Go through the steps explained in this tutorial and this tutorial to set up a REST Consumer & Provider with Spring Cloud Contract
   • use one interaction of the API you defined in Task #1 instead of the API described in the tutorials
3. If you need orientation, have a look at the complete example: consumer and producer
4. Run ./gradlew build in the consumer and producer codebase to check that the consumer and producer tests work as expected

Task #5: Use a Pact Broker

1. Insert the pact broker credentials you have been provided into the pact section of the build.gradle file of the consumer you created in Task #2
2. Run ./gradlew build in the consumer code base to create the pact file
3. Run ./gradlew pactPublish in the consumer code base to publish the pact to the broker
4. Visit the Pact Broker in your browser and check that the pact has been published
5. Replace the @PactFolder annotation in the provider test from Task #3 with the @PactBroker annotation to load the pact from the broker instead of from the file system

REST Contracts with Node

Task #6 Implement a REST Consumer with Node / React & Pact

1. Start with an empty workspace
2. Go through the steps explained in this tutorial to set up a consumer test that creates a pact file
   • use one interaction of the API you defined in Task #1 instead of the API described in the tutorial
   • choose different consumer and provider names to make your implementation unique
   • to publish the contract on a pact broker, use the pact broker credentials you have been provided
3. If you need orientation, have a look at the complete example
4. Run npm run test:pact to run the tests and check that a pact file has been created in the folder ./pacts

Task #7: Implement a REST Consumer with Angular & Pact

1. Download and install the latest NodeJS distribution at https://nodejs.org/en/download/
2. Verify that npm and Node are installed properly by calling node -v and npm -v
3. Start with the code in the folder consumer/pact-angular-consumer
4. Run npm install in the folder and check that a node_modules folder has been created
5. Run npm run test to verify that the Angular tests run on your machine (you need to have Google Chrome installed)
6. Go through the steps explained in this tutorial to set up a consumer test that creates a pact file
   • use one interaction of the API you defined in Task #1 instead of the API described in the tutorial
   • choose different consumer and provider names to make your implementation unique
7. If you need orientation, have a look at the complete example
8. Run npm run test again to run the tests and check that a pact file has been created in the pacts folder

Task #8: Implement a REST Provider with Node & Pact

1. Start with an empty workspace
2. Go through the steps explained in this tutorial to set up a provider test against the contract you have created in task #5 or #6
   • to load the contract from the pact broker, use the pact broker credentials you have been provided
3. If you need orientation, have a look at the complete example
4. Run npm run test:pact to run the provider tests and check make the test pass

Messaging Contracts

Task #9: Define a Messaging Contract

In a group of 2-3, dream up a use case and define a contract between a message consumer and a message producer.

• The contract should consist of one or two message types.
• Per message, define the JSON structure of the message body.
• Write down the definition in a text file or on paper for later reference.

Task #10: Implement a Spring Messaging Consumer & Provider with Pact

1. Start with the code in the folders consumer/pact-message-consumer and provider/pact-message-producer
2. Go through the steps explained in this tutorial to set up a Spring Messaging Consumer and Producer that satisfy the contract from Task #8
3. If you need orientation, have a look at the complete example: consumer and producer
4. Run ./gradlew build in the consumer and producer codebase to check that the consumer and producer tests work as expected

Task #11: Implement a Node Messaging Consumer & Provider with Pact

1. Start with an empty workspace
2. Go through the steps explained in this tutorial to set up a Node Messaging Consumer and Producer that satisfy the contract from Task #8
3. If you need orientation, have a look at the complete example: consumer
4. Run npm run test:pact:consumer and npm run test:pact:provider to check that the consumer and producer tests work as expected

GraphQL Contracts

Task 12: Define a GraphQL Contract

In a group of 2-3, dream up a use case and define a GraphQL Schema

• The contract should consist of one or two interactions
• Write down the definition in a text file or on paper for later reference.

Task #13: Implement a Node-based GraphQL Consumer with Pact

1. Start with an empty workspace
2. Go through the steps explained in this tutorial to set up a Node GraphQL Consumer
   • use one interaction of the API you defined in Task #12
   • choose different consumer and provider names than the ones used in the tutorial to make your implementation unique
   • to publish the contract on a pact broker, use the pact broker credentials you have been provided
3. If you need orientation, have a look at the complete example
4. Run npm run test:pact:graphql to check that the consumer test works as expected

Task #14 Implement a Node-based GraphQL Provider with Pact

1. Start with an empty workspace
2. Go through the steps explained in this tutorial to set up a Node GraphQL Provider
   • to load the contract from the pact broker, use the pact broker credentials you have been provided
3. If you need orientation, have a look at the complete example
4. Run npm run test:pact:graphql to check that the provider test works as expected