However if all you want to do is log the val to the console, use

val.apply((contents) => console.log(contents));

There is an internal Pulumi function that immediately returns a Promise from an Output. This is described in the GitHub issue. It can be useful when unit testing, because there are unit testing libraries that support Promises, but none that support Outputs.

The alternative is to make your unit test fully async (which Jest and Mocha support, and probably all common libraries), and do your assertions inside

apply()

blocks.

However your original question seems only to want to know how to look at the contents of an output, rather than how to assert on them.

In which case, simply moving your log statement into the apply block is all you need to do.

I do not appear to be getting output to the console using this snippet

describe('yaml', function () {
    it('reads', function (done) {
      pulumi.all([infra.ymml.urn, infra.ymml]).apply(([urn, thefile]) => {
        console.log(urn);
        var val = thefile.getResource('v1/Service', 'my-service');
        val.apply((content) => console.log(content.apiVersion));
        done();
      });
    });
  });
});

where

foo.yaml

looks like this

apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: MyApp
  ports:
    - protocol: TCP
      port: 80
      targetPort: 9376

the output is

yaml
urn:pulumi:stack::project::kubernetes:yaml:ConfigFile::yamlfile
      ✓ reads
(node:72056) PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 3)
(Use `node --trace-warnings ...` to show where the warning was created)
(node:72056) PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 4)

The problem with using apply in tests is that the tests may finish before the promise resolves. Or as in this case, the promise may be rejected, leaving you with very little information.

I think you need to add

async

to the function you pass to

it

It's not waiting for the apply to finish.