test: create script to merge coverage reports

tools/merge-coverage.js

@@ -0,0 +1,91 @@
+const { existsSync, readFileSync } = require('fs');
+const glob = require('glob');
+const { createCoverageMap } = require('istanbul-lib-coverage');
+const { createContext } = require('istanbul-lib-report');
+const { create: createReporter } = require('istanbul-reports');
+const yargs = require('yargs');
+
+const COVERAGE_FOLDER = 'coverage';
+
+function mergeCoverage(
+  coverageFolder = COVERAGE_FOLDER,
+  reporters = ['json', 'lcov', 'text'],
+  basePath = ''
+) {
+  const coverageMap = createCoverageMap({});
+  const pattern = basePath
+    ? `${basePath}/${coverageFolder}/**/coverage-final.json`
+    : `${coverageFolder}/**/coverage-final.json`;
+  const reportFiles = glob.sync(pattern);
+  reportFiles.forEach((coveragePath) => {
+    if (!existsSync(coveragePath)) {
+      return;
+    }
+    let coverage = JSON.parse(readFileSync(coveragePath, 'utf8'));
+    if (process.env.CI) {
+      // fix invalid file path in Github actions
+      coverage = Object.keys(coverage).reduce((acc, key) => {
+        // make filepath relative to basePath instead of repository root
+        const { name } = require('../package.json');
+        const filePath = key.replace(`/home/runner/work/${name}/${name}/`, '');
+        const newKey = filePath;
+        coverage[key].path = filePath;
+        return { ...acc, [newKey]: coverage[key] };
+      }, {});
+    }
+    coverageMap.merge(coverage);
+  });
+
+  const coverageDir = basePath
+    ? `${basePath}/${coverageFolder}`
+    : coverageFolder;
+  const context = createContext({
+    dir: coverageDir,
+    coverageMap,
+  });
+
+  reporters.forEach((reporter) => {
+    const report = createReporter(reporter);
+    report.execute(context);
+  });
+  console.log(`Created a merged coverage report in ${coverageDir}`);
+}
+
+async function main() {
+  const argv = await yargs.options({
+    projectPaths: {
+      array: true,
+      type: 'string',
+      default: [],
+      alias: 'p',
+    },
+    reporters: {
+      array: true,
+      type: 'string',
+      default: ['json', 'lcov', 'text'],
+      demandOption: true,
+      alias: 'r',
+    },
+    coverageFolder: {
+      type: 'string',
+      default: COVERAGE_FOLDER,
+      demandOption: true,
+      alias: 'c',
+    },
+  }).argv;
+
+  const { coverageFolder, projectPaths, reporters } = argv;
+
+  if (projectPaths.length) {
+    projectPaths.forEach((basePath) => {
+      mergeCoverage(coverageFolder, reporters, basePath);
+    });
+  } else {
+    mergeCoverage(coverageFolder, reporters);
+  }
+}
+
+main().catch((err) => {
+  console.error(err);
+  process.exit(1);
+});