So I have this config:

.nycrc

  "extends": "@istanbuljs/nyc-config-typescript",
    "extension": [
      ".ts"
    ],
    "exclude": [
      "**/*.d.ts",
      "**/*.spec.ts"
    ],
    "reporter": [
      "html",
      "lcov",
      "text-summary"
    ],
    "lines": 90,
    "branches": 90,
    "functions": 90,
    "statements": 90,
    "report-dir": "coverage",
    "all": true  

.nyc-intrc

{
    "extends": "./.nycrc",
    "include": [
      "src/**/*.ts"
    ]
}

package.json

 "scripts": {
    "test:coverage:integration": "nyc --nycrc-path .nyc-intrc --cache false npm run test:integration",
    "test:integration": "mocha -r ts-node/register/transpile-only -r source-map-support/register --recursive 'src/*/__tests__/*.spec.ts' --reporter mochawesome --timeout 1500000"
  },

So running this using NPM (npm run test:coverage:integration) succeeds. However, the result is not accurate. Some files are reported to have 0% coverage, even though the tests trigger that code and it gets executed. I mean, I added a console.log to one of them. I can see the log in the output when running the tests, but the file still has 0% coverage and Istanbul says even that console.log statement wasn't executed.

Interestingly, this problem does not exist with unit tests. If I run those, the same file gets instrumented and the report is accurate.

I'm using Typescript 4.5.5, Mocha 9.2.0 and Node 14.x

How is this possible? What am I missing here?