esmock fails if source maps are used

[jakebailey]

I have a TS project using ava on TS's output. I have to do this as my project calls into import.meta.resolve / import-meta-resolve, and I want to test on my project as it ships to users. I have source maps enabled so that I can debug / run coverage on my tests.

Unfortunately, esmock doesn't seem to work if source maps are enabled.

Here's a minimal repro: https://github.com/jakebailey/esmock-source-map-bug

I suspect it's due to this:

esmock/src/esmock.js

Line 12 in 31cc298

const calleePath = (err || new Error).stack.split('\n')[2]

If source maps have been loaded, the backtrace will show the mapped location (my TS src dir), not the true location (a dist dir of compiled code). Maybe esmock's API should accept a parent parameter so that the caller can pass import.meta.url, similar to import-meta-resolve or other ESM-y APIs?

[iambumblehead]

If esmock's interface is updated to support a 'parent' value defined in the fourth parameter, would that be a good solution? what do you recommend?

const indexModule = await esmock("../index.js", {
  os: {
    hostname: () => expectedHostname,
  },
}, null, {
  parent: parentURL
});

[jakebailey]

It'd be an API break, but I would think this would be a required parameter, and "callePath" ceases to be automatically detected.

[jakebailey]

Just for reference for anyone finding this, my current workaround is this:

import { fileURLToPath } from "url";

export function fixESMockPath(path: string, importMetaUrl: string): string {
    const url = new URL(path, importMetaUrl);
    return fileURLToPath(url);
}

Then, when testing:

import test from "ava";
import esmock from "esmock";

import { fixESMockPath } from "./testUtils.js";
import type * as myModuleType from "../myModule.js";

test("do something", async (t) => {
    const myModule: typeof myModuleType = await esmock(fixESMockPath("../myModule.js", import.meta.url), {
        fs: {
            writeFile: () => { ... }
        },
        [fixESMockPath("../localLib.js", import.meta.url)]: {
            someFunction: () => { ... }
        },
    };

    const result = await myModule.doSomething(); // Run with the above modules mocked.
    t.is(result, 1234);
});

[iambumblehead]

resolved here #122 closing