.eslintrc.js

module.exports = {
  parser: '@typescript-eslint/parser',
  plugins: ['@typescript-eslint', 'jest'],
  extends: [
    'eslint:recommended',
    'plugin:@typescript-eslint/eslint-recommended',
    'plugin:@typescript-eslint/recommended',
    'plugin:@typescript-eslint/recommended-requiring-type-checking',
  ],
  ignorePatterns: ['.eslintrc.js'],
  parserOptions: {
    sourceType: 'module',
    ecmaFeatures: {
      jsx: false,
    },
    project: './tsconfig.eslint.json',
    tsconfigRootDir: __dirname,
  },
  rules: {
    '@typescript-eslint/consistent-type-definitions': ['error', 'interface'],
    '@typescript-eslint/explicit-function-return-type': 'error',
    '@typescript-eslint/no-empty-function': [
      'error',
      { allow: ['arrowFunctions'] },
    ],
  },
  overrides: [
    // all test files
    {
      files: ['test/**/*.spec.ts'],
      env: {
        jest: true,
      },
      extends: ['plugin:jest/recommended', 'plugin:jest/style'],
      rules: {
        'jest/no-disabled-tests': 'warn',
        'jest/no-test-return-statement': 'error',
        'jest/prefer-to-have-length': 'warn',
        'jest/prefer-spy-on': 'error',
      },
    },
  ],
};