ember-cli-code-coverage · kategengler · Mar 24, 2018 · Feb 27, 2018 · Mar 24, 2018
diff --git a/README.md b/README.md
@@ -30,9 +30,7 @@ and then:
 
 `cross-env COVERAGE=true ember test`
 
-Coverage also works when running tests in parallel, eg:
-
-`COVERAGE=true ember exam --split=2 --parallel=true`
+When running with `parallel` set to true, the final reports can be merged by using `ember coverage-merge`. The final merged output will be stored in the `coverageFolder`.
 
 ## Configuration
 
@@ -48,6 +46,8 @@ Configuration is optional. It should be put in a file at `config/coverage.js` (`
 
 - `coverageFolder`: Defaults to `coverage`. A folder relative to the root of your project to store coverage results.
 
+- `parallel`: Defaults to `false`. Should be set to true if parallel testing is being used for separate test runs, for example when using [ember-exam](https://github.com/trentmwillis/ember-exam) with the `--partition` flag. This will generate the coverage reports in directories suffixed with `_<random_string>` to avoid overwriting other threads reports. These reports can be joined by using the `ember coverage-merge` command (potentially as part of the [posttest hook](https://docs.npmjs.com/misc/scripts) in your `package.json`).
+
 #### Example
 ```js
   module.exports = {

diff --git a/index.js b/index.js
@@ -85,6 +85,12 @@ module.exports = {
     return undefined;
   },
 
+  includedCommands: function() {
+    return {
+      'coverage-merge': require('./lib/coverage-merge')
+    };
+  },
+
   /**
    * If coverage is enabled attach coverage middleware to the express server run by ember-cli
    * @param {Object} startOptions - Express server start options

diff --git a/lib/attach-middleware.js b/lib/attach-middleware.js
@@ -4,6 +4,7 @@ const bodyParser = require('body-parser').json({ limit: '50mb' });
 const istanbul = require('istanbul-api');
 const getConfig = require('./config');
 const path = require('path');
+const crypto = require('crypto');
 
 const WRITE_COVERAGE = '/write-coverage';
 
@@ -27,6 +28,15 @@ function writeCoverage(coverage, fileLookup, map) {
 function reportCoverage(map, root, configPath) {
   let config = getConfig(configPath);
   let reporter = istanbul.createReporter();
+  if (config.parallel) {
+    config.coverageFolder = config.coverageFolder + '_' + crypto.randomBytes(4).toString('hex');
+    if (config.reporters.indexOf('json') === -1) {
+      config.reporters.push('json');
+    }
+  }
+  if (config.reporters.indexOf('json-summary') === -1) {
+    config.reporters.push('json-summary');
+  }
   if (config.coverageFolder) {
     reporter.dir = path.join(root, config.coverageFolder);
   }

diff --git a/lib/coverage-merge.js b/lib/coverage-merge.js
@@ -0,0 +1,60 @@
+'use strict';
+
+var path = require('path');
+var getConfig = require('./config');
+var dir = require('node-dir');
+var Promise = require('rsvp').Promise;
+
+/**
+ * Merge together coverage files created when running in multiple threads,
+ * for example when being used with ember exam and parallel runs.
+ */
+module.exports = {
+  name: 'coverage-merge',
+  description: 'Merge multiple coverage files together.',
+  run: function () {
+    var istanbul = require('istanbul-api');
+    var config = this._getConfig();
+
+    var coverageFolderSplit = config.coverageFolder.split('/');
+    var coverageFolder = coverageFolderSplit.pop();
+    var coverageRoot = this.project.root + '/' + coverageFolderSplit.join('/');
+    var coverageDirRegex = new RegExp(coverageFolder + '_.*');
+
+    let reporter = istanbul.createReporter();
+    reporter.dir = path.join(coverageRoot, coverageFolder);
+    let map = istanbul.libCoverage.createCoverageMap();
+
+    return new Promise(function (resolve, reject) {
+      dir.readFiles(coverageRoot, { matchDir: coverageDirRegex, match: /coverage-final\.json/ },
+        function (err, coverageSummary, next) {
+          if (err) {
+            reject(err);
+          }
+          map.merge(JSON.parse(coverageSummary));
+          next();
+        },
+        function (err) {
+          if (err) {
+            reject(err);
+          }
+
+          if (config.reporters.indexOf('json-summary') === -1) {
+            config.reporters.push('json-summary');
+          }
+
+          reporter.addAll(config.reporters);
+          reporter.write(map);
+          resolve();
+        });
+    });
+  },
+
+  /**
+   * Get project configuration
+   * @returns {Configuration} project configuration
+   */
+  _getConfig: function () {
+    return getConfig(this.project.configPath());
+  }
+};
diff --git a/package.json b/package.json
@@ -38,6 +38,7 @@
     "fs-extra": "^5.0.0",
     "istanbul-api": "^1.1.14",
     "lodash.concat": "^4.5.0",
+    "node-dir": "^0.1.16",
     "rsvp": "^4.8.1",
     "walk-sync": "^0.3.2"
   },

diff --git a/test/integration/app-coverage-test.js b/test/integration/app-coverage-test.js
@@ -87,13 +87,31 @@ describe('app coverage generation', function() {
     });
   });
 
-  it('uses nested coverageFolder', function() {
+  it('uses parallel configuration and merges coverage when merge-coverage command is issued', function() {
+    expect(dir(`${app.path}/coverage`)).to.not.exist;
+    fs.copySync('tests/dummy/config/coverage-parallel.js', `${app.path}/config/coverage.js`);
+    process.env.COVERAGE = true;
+    return app.run('ember', 'exam', '--split=2', '--parallel=true').then(function() {
+      expect(dir(`${app.path}/coverage`)).to.not.exist;
+      return app.run('ember', 'coverage-merge');
+    }).then(function() {
+      expect(file(`${app.path}/coverage/lcov-report/index.html`)).to.not.be.empty;
+      expect(file(`${app.path}/coverage/index.html`)).to.not.be.empty;
+      var summary = fs.readJSONSync(`${app.path}/coverage/coverage-summary.json`);
+      expect(summary.total.lines.pct).to.equal(83.33);
+    });
+  });
+
+  it('uses nested coverageFolder and parallel configuration and run merge-coverage', function() {
     var coverageFolder = `${app.path}/coverage/abc/easy-as/123`;
 
     expect(dir(coverageFolder)).to.not.exist;
     fs.copySync('tests/dummy/config/coverage-nested-folder.js', `${app.path}/config/coverage.js`);
     process.env.COVERAGE = true;
     return app.run('ember', 'exam', '--split=2', '--parallel=true').then(function() {
+      expect(dir(coverageFolder)).to.not.exist;
+      return app.run('ember', 'coverage-merge');
+    }).then(function() {
       expect(file(`${coverageFolder}/lcov-report/index.html`)).to.not.be.empty;
       expect(file(`${coverageFolder}/index.html`)).to.not.be.empty;
       var summary = fs.readJSONSync(`${coverageFolder}/coverage-summary.json`);

diff --git a/tests/dummy/config/coverage-nested-folder.js b/tests/dummy/config/coverage-nested-folder.js
@@ -3,5 +3,6 @@
 
 module.exports = {
   coverageFolder: 'coverage/abc/easy-as/123',
+  parallel: true,
   reporters: ['lcov', 'html', 'text', 'json-summary']
 };
diff --git a/tests/dummy/config/coverage-parallel.js b/tests/dummy/config/coverage-parallel.js
@@ -0,0 +1,5 @@
+/* eslint-env node */
+
+module.exports = {
+  parallel: true
+};