[heft] NODE_ENV env variable not set during test phase

[anthony-legay]

Summary

So, the issue is pretty simple: Jest, as specified in its documentation should set 2 environment variables during its execution:
JEST_WORKER_ID and NODE_ENV (to value test).

Using heft test command which then calls Jest, it appears the NODE_ENV variable is not set, only JEST_WORKER_ID.
This breaks any test specific logic which uses this env variable.

As discussed with @octogonz:

However personally, I would prefer NOT to rely on something as brittle as an environment variable. It would be better to declare an API like if (TEST) { } or if (jestEnv.TEST) { } that can have proper TypeScript typings. My team was recently asked to set up something similar for passing down Webpack variables, so maybe these can be combined into a single API.

[octogonz]

Thanks for reporting this. I'll be back from vacation next week and can take a look.

Supporting the environment variable is relatively easy (and maybe could be done as a first PR to get you unblocked).

But we should work out the "right way" to pass down environment settings when using Heft. Seems like Webpack variables and Jest variables should be combined into a single global API.

[octogonz]

Let's use this issue to track the "easy" fix of exposing NODE_ENV to Heft's Jest environment. It is the title of this issue. If we want to provide a better way, we can create a separate issue to track that idea (or just make a PR).

@Lebowskovitch are you able to make a PR? Heft's Jest config is set up here.

[woss]

Since heft-jest-plugin is using the @jest/core the NODE_ENV is not set at all because jest sets it in the CLI and REPL scripts.

One way is to add the new optional field setNodeEnvVar to IJestPluginOptions where the default value would be true. If unchanged this would behave precisely as jest implementation:

NODE_ENV
Set to 'test' if it's not already set to something else.

If you agree with this I'll make a PR and add it, this would save me a lot of work of setting up the NODE_ENV for over 40 pacakges

Screenshot from the jest repo: