Example NodeJS Provider - Dredd
Source Code
https://github.com/pactflow/example-bi-directional-provider-dredd
: https://github.com/pactflow/example-bi-directional-provider-dredd/actions
Overview of Example
This is an example of a NodeJS "Product" API Provider that uses Dredd, Pact, API Hub for Contract Testing and GitHub Actions to generate and publish Pact provider contracts.
It performs pre-deployment cross-compatibility checks to ensure that it is compatible with specified consumers using the Bi-Directional contract capability of API Hub for Contract Testing.
See the full API Hub for Contract Testing Bi-Directional Workshop for which this can be substituted in as the "provider".
Key points
It:
Is an API written in Express JS
Has OAS 3.0 spec documenting the API
Uses Dredd for API testing to check spec compliance
What is uploaded to API Hub for Contract Testing is an OpenAPI specification that represents what you actually tested with Dredd, to give us confidence it is compatible with a Pact consumer.
Overview of Part of Bi-Directional Contract Testing Flow
In the following diagram, you can see how the provider testing process works.
When we call "can-i-deploy" the cross-contract validation process kicks off on API Hub for Contract Testing, to ensure any consumer consumes a valid subset of the OAS for the provider.
The project uses a Makefile to simulate a very simple build pipeline with two stages - test and deploy.
When you run the CI pipeline (see below for doing this), the pipeline should perform the following activities (simplified):
Test
Run tests to check spec compliance with openAPI spec
Publish provider contract (openAPI spec + results) to API Hub for Contract Testing
Check if we are safe to deploy to Production with
can-i-deploy(ie. has the cross-contract validation has been successfully performed)
Deploy (only from master)
Deploy app to Production
Record the Production deployment in the Pact Broker
Compatible with Consumers
This project is currently compatible with the following consumers(s):
See Environment variables on how to set these up
Pre-requisites
Software:
Environment variables
To be able to run some of the commands locally, you will need to export the following environment variables into your shell:
PACT_BROKER_TOKEN: a valid API token for API Hub for Contract TestingPACT_BROKER_BASE_URL: a fully qualified domain name with protocol to your pact broker e.g., https://testdemo.pactflow.io
Set PACT_PROVIDER to one of the following:
PACT_PROVIDER=pactflow-example-bi-directional-provider-dredd: Dredd - (https://github.com/pactflow/example-bi-directional-provider-dredd)PACT_PROVIDER=pactflow-example-bi-directional-provider-postman: Postman - (https://github.com/pactflow/example-bi-directional-provider-postman)PACT_PROVIDER=pactflow-example-bi-directional-provider-restassured: Rest Assured - (https://github.com/pactflow/example-bi-directional-provider-restassured)
Usage
Steps
make test- run the tests locallymake fake_ci- run the CI process, but locally
OS/Platform specific considerations
The makefile is configured to run on Unix based systems such as you would find in most common CI/CD pipelines.
They can be run locally on Unix/Mac, or on Windows via WSL2.
Windows
You can still try this example locally on Windows using powershell and running commands manually.
These will be the same commands that are used in the makefile with a few manual tweaks.
Make sure you have set all of the environment variables, in powershell they can be set like so.
$env:BRANCH="main"
Now that the Swagger doc is generated and verified the contract can be published to API Hub for Contract Testing. The easiest way to do this via windows is using our standalone tools. See here for cross platform instructions.
Check can-i-deploy to see if your provider is compatible with your pact.
docker run --rm -v <path_to_project_root>:<path_to_project_root> -e PACT_BROKER_BASE_URL -e PACT_BROKER_TOKEN pactfoundation/pact-cli broker can-i-deploy --pacticipant pactflow-example-bi-directional-consumer-dotnet --version $env:VERSION --to-environment production --retry-while-unknown 0 --retry-interval 10
Have a look at what other commands are available in the Makefile. All of them can be ran locally from Powershell by changing the windows paths to UNIX and replacing the environment variable references. Any variable referenced as
${VARIABLE}can be changed to$env:VARIABLEto reference environment variables in Powershell.
Caveats
You are responsible for ensuring sufficient OAS coverage. To highlight this point, in our example, we do not test the 404 case on the provider, but the consumer has a pact for it and it's tests still pass! NOTE: We plan to address this problem in the future
implementing a spec is not the same as being compatible with a spec. Most tools only tell you that what you’re doing is not incompatible with the spec. NOTE: We plan to address this problem in the future
Other examples of how to do this form of testing
TBC
Found an issue?
Reach out via a GitHub Issue, or reach us over in the Pact foundation Slack