Working with mocha and nyc

[reekoheek]

Hi,

I love esbuild-runner, however I tried to replace my toolchain for testing with esbuild-runner but I can't get the same result as ts-node did.

I ran nyc with mocha like this,

nyc mocha -r ts-node/register './src/**/*.test.ts' --extension ts

and replace with

nyc mocha -r esbuild-runner/register './src/**/*.test.ts' --extension ts

But it seemed I didn't get the same result as ts-node version

Thanks

[maplesteve]

@reekoheek Did you find a solution to use nyc with esbuild-runner? Or any other setup to get the coverage with esbuild?

[Ragnoroct]

I'd suggest just switching to c8 for coverage. That worked for me with esbuild and esbuild-runner

[reekoheek]

@reekoheek Did you find a solution to use nyc with esbuild-runner? Or any other setup to get the coverage with esbuild?

No solution yet. For now I use ts-node for coverage test

I'd suggest just switching to c8 for coverage. That worked for me with esbuild and esbuild-runner

Didn't success using c8 also. I use this command

c8 mocha -r esbuild-runner/register './src/**/*.test.ts' --extension ts

[rehanvdm]

I think I got it working. It is because it tries to bundle everything including the tests and then things go wrong, if you pass node a custom --require (aka -r) field to a file that uses esbuild-runner that just transpiles and not bundle, then it works.

These two commands do the same, just wanted to show that the --require flag is not even needed, you can just specify the file to be used.

node.exe ./node_modules/mocha/bin/mocha.js --require ./cli/tests/compile.js --ui bdd ./cli/tests/end-to-end/cli.spec.ts --grep "^E2E Not running$"

node.exe ./node_modules/mocha/bin/mocha.js ./cli/tests/compile.js --ui bdd ./cli/tests/end-to-end/cli.spec.ts --grep "^E2E Not running$"

./cli/tests/compile.js

require('esbuild-runner').install({
  type: "transform", //toalso  preserve debug points, else it bundles everything.
  // debug: true,
  esbuild: {
    //TODO can extend esbuild here with the same config as used by the actual build process
  }
});

In addition to that, the .mocharc file also uses that same require.

.mocharc.json

{
  "extension": ["spec.ts"],
  "spec": "tests/unit/*.spec.ts",
  "require": "./tests/compile.js"
}

[jlangsu]

As @rehanvdm stated, using different transform options is necessary unless you pre-instrument the sources.

An esbuild option that is necessary to output coverage is sourcemap: 'inline'. nyc lacks the ability to instrument the code when it lacks source maps and the coverage numbers are unknown.

Per the README here, create esbuild-runner.config.js in your package root, and configure your esbuild options including sourcemap: 'inline'. esbuild-runner/register will pick up the config options automatically.

esbuild-runner.config.js

module.exports = {
  type: 'transform',
  esbuild: {
    sourcemap: 'inline'
  }
}

Otherwise, you can create a custom "register" file for your tests, and reference it from your scripts.

package.json

"test": "mocha -r custom-register.js \"test/**/*.spec.ts\"",
"coverage": "nyc npm run mocha",

custom-register.js

require('esbuild-runner').install({
  type: 'transform', 
  esbuild: {
    sourcemap: 'inline'
  }
});

[sagia-inneractive]

If anybody bumps into this and is having issues using transform for his project, here is a configuration that worked for me on a pnpm workspace with nyc -

const fs = require("fs");

const out = {
    type: 'transform',
    external: [/*external stuff*/],
    esbuild: {
        tsconfigRaw: JSON.parse(fs.readFileSync('./tsconfig.json')),
        sourcemap: 'inline',
    }
}

module.exports = out

This seems to be working with simply invoking nyc + mocha