fix: override ts-node module behaviour [gh-768]

[clample]

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Affected Components

• CLI
• Create CLI
• Test
• Docs
• Examples
• Other

Notes for the Reviewer

Resolves #768

The bug

Currently the CLI is unable to support TypeScript checkly.config.ts and **.check.ts files in projects that are configured as ECMAScript Module projects. This can be reproduced by setting "type": "module" in package.json for the boilerplate project:

$ npx checkly deploy
Parsing your project... !
    Error: Error loading file /Users/clample/projects/test/amber-snake/checkly.config.ts
    Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: /Users/clample/projects/test/amber-snake/checkly.config.ts
    require() of ES modules is not supported.
    require() of /Users/clample/projects/test/amber-snake/checkly.config.ts from /Users/clample/projects/test/amber-snake/node_modules/checkly/dist/services/util.js is an ES module file as it is a .ts file whose nearest parent package.json contains "type": "module" which defines all .ts files in that package scope
    as ES modules.
    Instead change the requiring code to use import(), or remove "type": "module" from /Users/clample/projects/test/amber-snake/package.json.

        at createErrRequireEsm (/Users/clample/projects/test/amber-snake/node_modules/ts-node/dist-raw/node-internal-errors.js:46:15)
        at assertScriptCanLoadAsCJSImpl (/Users/clample/projects/test/amber-snake/node_modules/ts-node/dist-raw/node-internal-modules-cjs-loader.js:584:11)
        at Object.require.extensions.<computed> [as .ts] (/Users/clample/projects/test/amber-snake/node_modules/ts-node/src/index.ts:1610:5)
        at Module.load (node:internal/modules/cjs/loader:1004:32)
        at Function.Module._load (node:internal/modules/cjs/loader:839:12)
        at Module.require (node:internal/modules/cjs/loader:1028:19)
        at require (node:internal/modules/cjs/helpers:102:18)
        at /Users/clample/projects/test/amber-snake/node_modules/checkly/src/services/util.ts:69:54
        at processTicksAndRejections (node:internal/process/task_queues:96:5)
        at async loadTsFile (/Users/clample/projects/test/amber-snake/node_modules/checkly/src/services/util.ts:69:33)

The issue occurs when importing the project files via ts-node. The ts-node documentation has extensive notes on this: ts-node CommonJS vs native ECMAScript modules and ts-node Module type overrides.

The Fix

The Checkly CLI is currently compiled to CommonJS and the await import in loadTsFile is compiled to a require:

async function loadTsFile(filepath) {
    try {
        const tsCompiler = await getTsCompiler();
        tsCompiler.enabled(true);
        let { default: exported } = await (_a = filepath, Promise.resolve().then(() => require(_a)));
        if (exported instanceof Function) {
            exported = await exported();
        }
        tsCompiler.enabled(false); // Re-disable the TS compiler
        return exported;
    }
    catch (err) {
        throw new Error(`Error loading file ${filepath}\n${err.stack}`);
    }
}

One option could be to leave the MaC project code as an ECMAScript Module, and import it using a similar trick we use for .mjs support (here. This would be difficult, though, with ts-node. We would need to use ts-node's Native ECMAScript Modules Support, and this requires passing the --loader flag to node.

Instead, this PR configures ts-node to ignore the project's package.json and compile the code to CommonJS. This is described in ts-node Module Type Overrides. This let's us continue to require the project's checkly.config.ts and *.check.ts files.

One downside with this approach may be with projects importing other dependencies that are pure ESM packages. In this case, I think that they will run into ERR_REQUIRE_ESM.

[github-actions]

🎉 Experimental release successfully published on npm

npm install checkly@0.0.0-pr.804.7a3174d

[umutuzgur]

LGTM