4. Add Tests

Garden treats tests as a first class citizen and has a dedicated Test action kind. Let's add one for integration/end-to-end testing our project.

Step 1 — Add a Test action

In the ./web/garden.yml file, add the following below the Deploy action:

---
kind: Test
name: integ
type: container
dependencies: [deploy.web]
spec:
  image: ${actions.build.web.outputs.deploymentImageId}
  command: [npm, run, test:integ]

This action depends on the web service being deployed and will basically sit at the edge of the graph.

Step 2 — Run the test

Next, run the test with:

garden test

When you have multiple tests in your project you can also specify which one to run with garden test my-test-name.

Once the test passes, try running it again.

Notice how Garden tells you that the test has already passed?

This is Garden's caching mechanism at play. Garden knows exactly what files and configuration goes into each action (including upstream dependencies) and stores the version and results of each execution.

This can mean massive time savings for large projects, in particular in CI, where only the tests for the parts of the system that actually changed need to be re-run.

Step 3 – Break the test

Let's convince ourselves this works as expected. Open the ./api/app.py file and break the test by changing the following line:

if request.method == 'POST':

to:

if request.method == 'PUT':

Even though the test itself is defined in the ./web/garden.yml file, Garden knows that it depends on the API and that it needs to be re-run.

Try running it again with:

garden test

If you now undo the changes and change the request.method back to POST and run the test one more time, Garden will again tell us that it has already passed since now the action version should be the same as it was before.