Part 5: End-to-end Test

12 Jun 2019

Fifth part of the series about Azure Function in TypeScript where we add an end-to-end test.

The code base after this step.

In the previous step we enabled automatic creation of branch environments. Now let’s write a test that verifies the actual endpoint on Azure works. We can break it down into these three steps:

1. Compute the URL our greet function app in Azure environment associated with the current branch.
2. Call that endpoint, fetching some data.
3. Verify that we get a 200 OK back and that the returned data is what we expected.

Local Tests and End-to-end Tests

Our tests are currently being executed before we deploy to Azure, but since we now want to verify the deployed code, we will add a second type of test that will run after deployment. We will call the second type of tests end-to-end tests, and for the lack of better name, we will call the other tests local tests.

Because of the slower execution time and because a failing end-to-end tests won’t stop deployment, I recommend that you write most of your tests as local tests, and only have a few end-to-end tests verifying the deployed code. The short command test runs the local tests.

Getting the Root URL of the Endpoints

TestHelper.getApiRootUrl() gets the root API url through the resource group. This could have been simplified a lot by simply computing the URL using the current branch name (https://aft-${branchName}-functions/api), but the current solution also works if uniqueString had been used for the name of the function app resource, and I thought that this snippet might be useful to someone, so I left it in.

1. Get the name of current branch with the shell command git symbolic-ref --short HEAD.
2. Use the branch name to compute the name of the resource group.
3. Get a list of all the resources in that group with the shell command az resource --list ....
4. The function app resource is the one with a name that matches aft-*-functions.
5. Return the full URL by adding .azurewebsites.net/api.

private static getApiRootUrl(): string {
  const currentBranchName = this.runShellCommand(
    "git symbolic-ref --short HEAD"
  ).trim();
  const resourceGroupName = `azure-functions-typescript-${currentBranchName}`;
  const resourcesInfo = this.runShellCommand(
    `${this.azCommand} resource list --resource-group ${resourceGroupName}`
 );
  const resourceInfos = JSON.parse(resourcesInfo) as Array<ResourceInfo>;
  const functionsResourceName = resourceInfos
    .map(resourceInfo => resourceInfo.name)
    .find(
      resourceName => resourceName.match(/^aft-(.*)-functions$/) !== null
    );

  if (functionsResourceName === undefined) {
    throw new Error(
      `Could not a functions resources in the resource group '${resourceGroupName}'.`
    );
  }

  return `https://${functionsResourceName}.azurewebsites.net/api`;
}