Answers

1. An environment variable called CI needs to be set to true for Jest tests to work well in a CI environment.
2. When we change the azure-pipelines.yml file, it is automatically committed and pushed to our master branch in our source code repository. The trigger option in the file specifies that a build should trigger when code is pushed to the master branch. So, a build is triggered when this happens.
3. The -script task can be used to execute npm commands.
4. The PublishBuildArtifacts@1 task can be used to publish artifacts to the pipeline.
5. The frontend build sets an environment variable called REACT_APP_ENV, which the code uses to determine which environment it is in. This is the reason we have different frontend builds.
6. The Azure App Service Deploy task type in a release pipeline stage can be used to deploy build artifacts to Azure App Service.