getAmi function causes warning in test mode

[clstokes]

If my Pulumi application uses getAmi to find an AMI, I get a confusing warning when running tests against the application with PULUMI_TEST_MODE. If I remove the getAmi call and hardcode an AMI ID, the test execution completes without any warning. I haven't tested if other lookup function calls cause the same warning.

Code to reproduce is at https://github.com/clstokes/pulumi-aws-ts-ruby-on-rails-unit-testing/tree/clstokes/get-ami-warning (note the clstokes/get-ami-warning branch).

Output with warning:

$ npm run test

> aws-ts-ruby-on-rails@0.1.0 test /Users/clstokes/cc/clstokes/pulumi-aws-ts-ruby-on-rails-unit-testing
> PULUMI_TEST_MODE=true PULUMI_NODEJS_PROJECT=aws-ts-ruby-on-rails PULUMI_NODEJS_STACK=fake-stack PULUMI_CONFIG='{ "aws:region": "us-west-2", "aws-ts-ruby-on-rails:dbUser": "admin2", "aws-ts-ruby-on-rails:dbPassword": "pass2", "aws-ts-ruby-on-rails:dbRootPassword": "pass2" }' mocha -r ts-node/register *.spec.ts



(node:31550) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'invoke' of undefined
    at /Users/clstokes/cc/clstokes/pulumi-aws-ts-ruby-on-rails-unit-testing/node_modules/@pulumi/pulumi/runtime/invoke.js:63:114
    at new Promise (<anonymous>)
    at Object.<anonymous> (/Users/clstokes/cc/clstokes/pulumi-aws-ts-ruby-on-rails-unit-testing/node_modules/@pulumi/pulumi/runtime/invoke.js:63:63)
    at Generator.next (<anonymous>)
    at fulfilled (/Users/clstokes/cc/clstokes/pulumi-aws-ts-ruby-on-rails-unit-testing/node_modules/@pulumi/pulumi/runtime/invoke.js:17:58)
    at processTicksAndRejections (internal/process/task_queues.js:89:5)
(node:31550) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 2)
(node:31550) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
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  1 passing (234ms)

The Pulumi runtime detected that 120 promises were still active
at the time that the process exited. There are a few ways that this can occur:
  * Not using `await` or `.then` on a Promise returned from a Pulumi API
  * Introducing a cyclic dependency between two Pulumi Resources
  * A bug in the Pulumi Runtime

Leaving promises active is probably not what you want. If you are unsure about
why you are seeing this message, re-run your program with the `PULUMI_DEBUG_PROMISE_LEAKS`
environment variable. The Pulumi runtime will then print out additional
debug information about the leaked promises.

[ellismg]

I would expect that all of these functions would fail because their implementations require a call into the engine in order to invoke data sources on the underlying providers, I don’t think there is a good way we can make things like getAmi work in general in test mode.

I think the best we could do here is make invokes fail with an exception in “test mode”

[lukehoban]

Closing this out as part of what's being tracked in #2932.