Jest coverage in a node typescript project always returns empty

Question

I am working on backend Typescript project when i am trying to get coverage report for unit test case,Jest returns empty coverage report in terminal as well as in html report stating nothing. i also tried with -- --coverage --watchAll=false but it also returns the empty document. I could not able to found a solution for this issue. can anyone help me to figureout what i am doing wrong here?

package.json

"scripts":{
    "unit-test": "jest --config='./config/jest/jest_unit.config.js' --forceExit --detectOpenHandles",
}

jest_unit.config.js

/**
 * @file Jest Unit Test Configuration File
 */
module.exports = {
  roots: ['../../tests'],
  testRegex: '.*_unit.test.(js|ts|tsx)?$',
  globals: {
    'ts-jest': {
      tsConfig: 'tsconfig.json',
    },
  },
  moduleFileExtensions: ['ts', 'js'],
  transform: {
    '^.+\\.(ts|tsx)$': 'ts-jest',
  },
  testEnvironment: 'node',
  reporters: [
    'default',
    [
      '../../node_modules/jest-html-reporter',
      {
        pageTitle: 'Unit Test Report',
        outputPath: 'tests/reports/unit-test-report.html',
        includeFailureMsg: true,
      },
    ],
  ],
  collectCoverage: true,
  collectCoverageFrom: [
    '../../api/**/*.ts'
  ],
  moduleFileExtensions: ["ts", "js", "json"],
  coverageDirectory: "../../coverage",
  coveragePathIgnorePatterns: [
    "<rootDir>/node_modules"
  ],
  coverageReporters: [
    "json",
    "lcov",
    "text"
  ],
  coverageThreshold: {
    "global": {
      "branches": 100,
      "functions": 100,
      "lines": 100,
      "statements": 100
    }
  },
};

Folder Structure

|-- app
    |-- controllers
    |-- schemas
|-- config
    |-- jest
        |-- jest_unit.config.js
|-- package.json
|-- tests
    |-- api
        |-- modules
            |-- m1
                |-- controllers
                    |-- m1_controller_unit.test.ts
                    |-- m1_controller_integration.test.ts
            |-- m2
                |-- models
                    |-- m1_model_unit.test.ts
                    |-- m1_model_integration.test.ts
            |-- m3
                |-- schemas
                    |-- m1_schema_unit.test.ts
                    |-- m1_schema_integration.test.ts

Jest Coverage htm and terminal shows no coverage lines

Answer 1

Can able to fix this issue by moving config file to root, Everything is good here in configuration, I dont know why jest behaves like this.

Updated structure

Folder Structure

|-- app
    |-- controllers
    |-- schemas
|-- jest_unit.config.js
|-- package.json
|-- tests
    |-- api
        |-- modules
            |-- m1
                |-- controllers
                    |-- m1_controller_unit.test.ts
                    |-- m1_controller_integration.test.ts
            |-- m2
                |-- models
                    |-- m1_model_unit.test.ts
                    |-- m1_model_integration.test.ts
            |-- m3
                |-- schemas
                    |-- m1_schema_unit.test.ts
                    |-- m1_schema_integration.test.ts

package.json

"scripts":{
    "unit-test": "jest --config='./jest_unit.config.js' --forceExit --detectOpenHandles",
}

Answer 2

Try changing your collectCoverageFrom as follows:

  collectCoverageFrom: [
    '../../tests/**'
  ],

The ** means to include all files, recursively. Details are at https://jestjs.io/docs/en/configuration#collectcoveragefrom-array

Answer 3

I'm also facing that issue randomly, I don't have a fix or know why, but clearing the cache and running it again always works:

jest --clearCache

jest --coverage

I believe this might be related to ts-jest not jest itself.

Answer 4

I got it working with this

package.json

...
"scripts": {
        ...
        "test": "jest --maxWorkers=1 --coverage"
...

jest.config.js

module.exports = {
    verbose: true,
    preset: 'ts-jest',
    testEnvironment: 'node',
    globals: {
        'ts-jest': {
            isolatedModules: true
        }
    },
    testPathIgnorePatterns: ['.d.ts', '.js'],
    collectCoverageFrom: [
        '**/*.ts',
        '!**/build/**',
        '!**/node_modules/**',
        '!**/vendor/**'
    ]
};