support arbitrary `import.meta.*` syntax (vitest insource testing)

[musicq]

Environment

• Node: v18.16.1
• Jiti: 1.20.0

Reproduction

if (import.meta.vitest) {}

Describe the bug

I'm using vitest with insource testing, it uses a specific variable import.meta.vitest which is not supported by jiti.

Additional context

No response

Logs

console.log(import.meta.vitest);
                   ^^^^

SyntaxError: Cannot use 'import.meta' outside a module
    at new Script (node:vm:100:7)

[pi0]

Thanks for reporting issue.

I really do hope if vitest could also support import.meta.env.vitest or import.meta.env.test as an alternative which is currently well supported in jiti.

But we might also think to support this specific import.meta key from import-meta-env.ts transformer.

/cc @antfu

[antfu]

import.meta.vitest is actually the whole vitest module, the full usage would be:

// in-source test suites
if (import.meta.vitest) {
  const { it, expect } = import.meta.vitest
  it('add', () => {
    expect(add()).toBe(0)
    expect(add(1)).toBe(1)
    expect(add(1, 2, 3)).toBe(6)
  })
}

It's not just a flag, so it probably can't be in import.meta.env, and probably won't work in jiti's env anyway. The work on #158 might solve this.

[pi0]

Thanks for explaining now it makes sense. It is different from #158 i guess the goal here is make same .ts code runnable both in jiti and vitest environments.

console.log(import.meta.vitest); in a normal .mjs files returns undefined so i think that's something we can fix in jiti transformer. (once had ESM support with jiti.import() or another workaround)

[antfu]

Yeah I think import.meta should be polyfilled in non-esm jiti env as it's designed to hold arbitrary data

[Barbapapazes]

I've got a similar issue. I'm trying to use parseMarkdown from https://github.com/nuxt-modules/mdc/blob/main/README.md#parsing-markdown within a script that is run by jiti.

 ERROR  Cannot use 'import.meta' outside a module                                                                                                         2:56:12 PM

  if (import.meta.dev)
  ^^^^
  
  SyntaxError: Cannot use 'import.meta' outside a module
  at new Script (node:vm:99:7)

[RebeccaStevens]

I get this trying to use import.meta.dirname

[pi0]

#300 adds a fallback loader to support this usage (need to use jiti.import)