Create a Mock (YAML)

Use YAML when the mock shape is mostly declarative and you want the runtime definition to stay easy to scan: where the DataSources come from, which Stub processes them, and which Server endpoint exposes them. QaaS.Mocker reads those sections into the same execution builder concepts you will use in larger mocks later.

This version keeps the mock definition in mocker.qaas.yaml and uses a small local processor for the response body.

The completed sample is available at DummyAppMock (YAML).

Scenario

The mock should:

• listen on http://127.0.0.1:8080
• return JSON from GET /data
• load the response body from ServerData/sample.json

Create the Project

dotnet new qaas-mocker -n DummyAppMock
cd DummyAppMock
dotnet add DummyAppMock/DummyAppMock.csproj package QaaS.Common.Generators

The sample keeps the response Processor local so the quick start stays compatible with the currently published public packages.

Keep Program.cs Minimal

DummyAppMock/Program.cs

QaaS.Mocker.Bootstrap.New(args).Run();

This host is YAML-only. Empty program arguments therefore show help text, so the run command must pass run mocker.qaas.yaml explicitly.

Add the Local Processor

The YAML file will only describe the mock flow. The actual response body is produced by a small local processor that loads the JSON payload from the data source and returns it with an HTTP 200 response.

DummyAppMock/Processors/ServerDataProcessor.cs

using System.Collections.Immutable;
using QaaS.Framework.SDK.DataSourceObjects;
using QaaS.Framework.SDK.Extensions;
using QaaS.Framework.SDK.Hooks.Processor;
using QaaS.Framework.SDK.Session.DataObjects;
using QaaS.Framework.SDK.Session.MetaDataObjects;

namespace DummyAppMock.Processors;

public sealed class ServerDataProcessor : BaseTransactionProcessor<NoConfiguration>
{
    public override Data<object> Process(IImmutableList<DataSource> dataSourceList, Data<object> requestData)
    {
        var response = dataSourceList
            .GetDataSourceByName("ServerData")
            .Retrieve()
            .FirstOrDefault();

        return new Data<object>
        {
            Body = response?.Body ?? "{}"u8.ToArray(),
            MetaData = new MetaData
            {
                Http = new Http
                {
                    StatusCode = 200,
                    ResponseHeaders = new Dictionary<string, string>
                    {
                        ["Content-Type"] = "application/json"
                    }
                }
            }
        };
    }
}

public sealed record NoConfiguration;

Add the Response File

DummyAppMock/ServerData/sample.json

{
  "message": "hello from DummyAppMock",
  "source": "dummy_app_mock"
}

Start with the DataSources Section

Begin by telling Mocker where the response payload lives through DataSources.

DummyAppMock/mocker.qaas.yaml

DataSources:
  - Name: ServerData
    Generator: FromFileSystem
    GeneratorConfiguration:
      DataArrangeOrder: AsciiAsc
      FileSystem:
        Path: ServerData

This means: "load files from the local ServerData folder and expose them as a named data source called ServerData."

Add the Stubs Section

Next add the transaction stub that connects the incoming request to your local processor.

Append this section to mocker.qaas.yaml:

Stubs:
  - Name: ServerDataStub
    Processor: ServerDataProcessor
    DataSourceNames: [ServerData]

The Stub says that when a request reaches this action, Mocker should call ServerDataProcessor and give it the ServerData data source.

Add the Servers Section

Finally define the Server and map GET /data to the stub you just created.

Append this section to mocker.qaas.yaml:

Servers:
  - Http:
      Port: 8080
      IsLocalhost: false
      Endpoints:
        - Path: /data
          Actions:
            - Name: GetServerData
              Method: Get
              TransactionStubName: ServerDataStub

This is the actual mock surface: open port 8080, listen locally, and route GET /data to the stub named ServerDataStub.

Full mocker.qaas.yaml

DataSources:
  - Name: ServerData
    Generator: FromFileSystem
    GeneratorConfiguration:
      DataArrangeOrder: AsciiAsc
      FileSystem:
        Path: ServerData

Stubs:
  - Name: ServerDataStub
    Processor: ServerDataProcessor
    DataSourceNames: [ServerData]

Servers:
  - Http:
      Port: 8080
      IsLocalhost: false
      Endpoints:
        - Path: /data
          Actions:
            - Name: GetServerData
              Method: Get
              TransactionStubName: ServerDataStub

Run the Mock

From DummyAppMock/DummyAppMock:

dotnet run -- run mocker.qaas.yaml

Then verify it:

curl http://127.0.0.1:8080/data

The mock keeps running after the check. Stop it with Ctrl+C when you are done.