1 files changed, 31 insertions, 0 deletions
diff --git a/scripts/frontend/merge_coverage_frontend.js b/scripts/frontend/merge_coverage_frontend.js
new file mode 100644
index 00000000000..507695b45e5
--- /dev/null
+++ b/scripts/frontend/merge_coverage_frontend.js
@@ -0,0 +1,31 @@
+const { create } = require('istanbul-reports');
+const { createCoverageMap } = require('istanbul-lib-coverage');
+const { createContext } = require('istanbul-lib-report');
+const { resolve } = require('path');
+const { sync } = require('glob');
+
+const coverageMap = createCoverageMap();
+
+const coverageDir = resolve(__dirname, '../../coverage-frontend');
+const reportFiles = sync(`${coverageDir}/*/coverage-final.json`);
+
+// Normalize coverage report generated by jest that has additional "data" key
+// https://github.com/facebook/jest/issues/2418#issuecomment-423806659
+const normalizeReport = report => {
+  const normalizedReport = Object.assign({}, report);
+  Object.entries(normalizedReport).forEach(([k, v]) => {
+    if (v.data) normalizedReport[k] = v.data;
+  });
+  return normalizedReport;
+};
+
+reportFiles
+  .map(reportFile => require(reportFile))
+  .map(normalizeReport)
+  .forEach(report => coverageMap.merge(report));
+
+const context = createContext({ coverageMap: coverageMap, dir: 'coverage-frontend' });
+
+['json', 'lcov', 'text-summary', 'clover'].forEach(reporter => {
+  create(reporter, {}).execute(context);
+});