Jest get coverage programmatically (gitlab pipelines)

README.md

node getCoverage.js

=>

CoverageSummary {
  data: {
    lines: { total: 10, covered: 10, skipped: 0, pct: 10.0 },
    statements: { total: 10, covered: 10, skipped: 0, pct: 10.0 },
    functions: { total: 10, covered: 10, skipped: 0, pct: 10.0 },
    branches: { total: 10, covered: 10, skipped: 0, pct: 10.0 }
  }
}

getCoverage.js

const jest = require('jest');
const config = require('jest-config');
const projects = ['.'];

jest.runCLI(config, projects).then((res) => console.log(res.results.coverage));

jest.config.js

// For a detailed explanation regarding each configuration property, visit:
// https://jestjs.io/docs/en/configuration.html

module.exports = {
  testResultsProcessor: '<rootDir>/jest.testResultsProcessor.js',
};

jest.testResultsProcessor.js

const reporter = require('istanbul-lib-coverage');

module.exports = function testResultsProcessor(options) {
  const coverage = reporter.createCoverageSummary();
  const coverageMap = reporter.createCoverageMap(options.coverageMap);
  coverageMap.files().forEach((file) => coverage.merge(coverageMap.fileCoverageFor(file).toSummary()));
  return { ...options, coverage };
};