Specmatic Sample: .NET core BFF calling Domain API

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• Specmatic Documentation

This sample project demonstrates below aspects of Contract-Driven Development

• Contract testing a .NET core (C#) application by leveraging its OpenAPI spec to generate tests (#NOCODE)
• Service Virtualization (Stub / Mock) dependencies of this application (System Under Test), again using OpenAPI specifications of those dependency services (#NOCODE)

Background

The Backend For Frontend (BFF) application here is the System Under Test (SUT). It depends on Domain API service which is being Stubbed out using Specmatic thereby effectively isolating the SUT so that we can now use Specmatic to run Contract Tests. Both Service Stubbing and Contract Testing is based on OpenAPI specifications here.

Tech Stack

1. .NET core (version 8)
2. Specmatic
3. Test Containers
4. Docker Desktop (on Local) and Test Container Cloud (in CI)
5. If you are on a Windows OS, please use PowerShell.

Running Tests

This will start the specmatic stub server for domain api using the information in specmatic.yaml and run contract tests using Specmatic.

dotnet test

Understand how to run the tests step by step

• Start Docker Desktop
• Navigate to Project (cd specmatic-order-bff-csharp)
• Run the application dotnet run
• Navigate to test Project (cd specmatic-order-bff-csharp.test)
• Start the stub Server docker run -v "$PWD/specmatic.yaml:/usr/src/app/specmatic.yaml" -v "$PWD/examples:/usr/src/app/examples" -p 9000:9000 znsio/specmatic stub --examples=examples
• Run the tests docker run --network host -v "$PWD/specmatic.yaml:/usr/src/app/specmatic.yaml" -v "$PWD/build/reports/specmatic:/usr/src/app/build/reports/specmatic" znsio/specmatic test --port=8080 --host=host.docker.internal

Break down each component to understand what is happening

Start the dependent components

Start domain api stub server

cd specmatic-order-bff-csharp.test
docker run -v "$PWD/specmatic.yaml:/usr/src/app/specmatic.yaml" -v "$PWD/examples:/usr/src/app/examples" -p 9000:9000 znsio/specmatic stub --examples=examples

Start BFF Server

This will start the .NET core BFF server

cd specmatic-order-bff-csharp
dotnet run

Test if everything is working

Note: For Windows OS, add .exe extension to curl command on PowerShell or use cmd.exe instead.

curl -H "pageSize: 10" "http://localhost:8080/findAvailableProducts?type=gadget"

You result should look like:

[{"id":10,"name":"iPhone","type":"gadget","inventory":701}]

Note: You might not get 701 for inventory, it can return can random integer.

Also observe the logs in the Specmatic HTTP Stub Server.