How do I substitute values appsettings.json in a test project in Azure DevOps release pipeline?

Question

What do I have

• In my release pipeline I use IIS Web App Deployment Task that does a variable substitution in appsettings.json:

  

• I want to run some integration and end to end tests:

  

Question

1. How do I replace settings appsettings.json related to my test projects.
2. How do I force the test runner to use a specific environment, e.g Staging, so that appsettings.Staging.json will is picked?

Answer 1

1. How do I replace settings appsettings.json related to my test projects.

   There is File Trasnform task that does the variable substitution exactly like IIS Web App Deployment Task but in a separate step.

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2. How do I force the test runner to use a specific environment, e.g Staging, so that appsettings.Staging.json will is picked?

   Environment variables like ASPNETCORE_ENVIRONMENT can be configured in a .runsettings file:

    <?xml version="1.0" encoding="utf-8"?>
    <RunSettings>
      <RunConfiguration>
        <EnvironmentVariables>
          <ASPNETCORE_ENVIRONMENT>Development</ASPNETCORE_ENVIRONMENT>
        </EnvironmentVariables>
      </RunConfiguration>
    </RunSettings>
   

   The value of environment variable can be then replaced in a separate pipeline step. I've used powershell task:

    steps:
    - powershell: |
       $fileName = "$(System.DefaultWorkingDirectory)/MyBuildArtifact/test.runsettings";
       [xml]$xml = Get-Content $fileName
       $xml.SelectSingleNode("//ASPNETCORE_ENVIRONMENT").InnerText = "$(System.StageDisplayName)";
       $xml.Save($fileName);
      failOnStderr: true
      showWarnings: true
      displayName: 'Configure ASPNETCORE_ENVIRONMENT'
   

I also needed to make sure the test.runsettings file is included in my build artifact and configure the Visual Studio Test task to use that file