Jest configuration (with code coverage) - SEE COMMENT IN FRIST LINE FOR IMPORTANT VERSION DETAILS

jest.config_spfx-1.14_ts-3.9.json

// for SPFx <= v1.14 projects & TypeScript <= v3.9
{
  "collectCoverage": true,
  "coverageDirectory": "<rootDir>/../temp/test",
  "coverageReporters": [
    "json",
    "lcov",
    "text-summary"
  ],
  "coverageThreshold": {
    "global": {
      "branches": 50,
      "functions": 90,
      "lines": 100,
      "statements": 100
    }
  },
  "globals": {
    "ts-jest": {
      "diagnostics": {
        "ignoreCodes":  "TS151001"
      }
    }
  },
  "moduleFileExtensions": [
    "ts",
    "tsx",
    "js",
    "json"
  ],
  "moduleNameMapper": {
    "\\.(css|scss)$": "identity-obj-proxy",
    "^resx-strings/en-us.json": "<rootDir>/../node_modules/@microsoft/sp-core-library/lib/resx-strings/en-us.json"
  },
  "reporters": [
    "default",
    [
      "jest-junit",
      {
        "output": "./temp/test/junit.xml"
      }
    ]
  ],
  "rootDir": "../src",
  "testMatch": [
    "**/src/**/*.spec.+(ts|tsx|js)"
  ],
  "testURL": "http://localhost",
  "transform": {
    "^.+\\.(ts|tsx)$": "ts-jest"
  },
  "verbose": true
}

jest.config_spfx-1.15_ts-4.5.json

// for SPFx >= v1.15 projects & TypeScript >= v4.5
{
  "collectCoverage": true,
  "coverageDirectory": "<rootDir>/../temp/test",
  "collectCoverageFrom": [
    "<rootDir>/**/*.{ts,tsx}",
    "!<rootDir>/**/*.scss.*",
    "!<rootDir>/**/webparts/**/*.ts",
    "!<rootDir>/loc/**/*.*"
  ],
  "coverageReporters": [
    "json",
    "lcov",
    "text-summary"
  ],
  "coverageThreshold": {
    "global": {
      "branches": 50,
      "functions": 90,
      "lines": 100,
      "statements": 100
    }
  },
  "globals": {
    "ts-jest": {
      "diagnostics": {
        "ignoreCodes":  "TS151001"
      }
    }
  },
  "moduleFileExtensions": [
    "ts",
    "tsx",
    "js",
    "json"
  ],
  "moduleNameMapper": {
    "\\.(css|scss)$": "identity-obj-proxy",
    "^resx-strings/en-us.json": "<rootDir>/../node_modules/@microsoft/sp-core-library/lib/resx-strings/en-us.json"
  },
  "reporters": [
    "default",
    [
      "jest-junit",
      {
        "outputDirectory": "temp/test",
        "outputName": "junit.xml"
      }
    ]
  ],
  "rootDir": "../src",
  "testMatch": [
    "**/src/**/*.spec.+(ts|tsx|js)"
  ],
  "testEnvironmentOptions": {
    "url": "http://www.something.com/test.html"
  },
  "transform": {
    "^.+\\.(ts|tsx)$": "ts-jest"
  },
  "verbose": true
}