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node_modules/mocha/lib/nodejs/worker.js

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+/**
+ * A worker process.  Consumes {@link module:reporters/parallel-buffered} reporter.
+ * @module worker
+ * @private
+ */
+
+'use strict';
+
+const {
+  createInvalidArgumentTypeError,
+  createInvalidArgumentValueError
+} = require('../errors');
+const workerpool = require('workerpool');
+const Mocha = require('../mocha');
+const {handleRequires, validateLegacyPlugin} = require('../cli/run-helpers');
+const d = require('debug');
+const debug = d.debug(`mocha:parallel:worker:${process.pid}`);
+const isDebugEnabled = d.enabled(`mocha:parallel:worker:${process.pid}`);
+const {serialize} = require('./serializer');
+const {setInterval, clearInterval} = global;
+
+let rootHooks;
+
+if (workerpool.isMainThread) {
+  throw new Error(
+    'This script is intended to be run as a worker (by the `workerpool` package).'
+  );
+}
+
+/**
+ * Initializes some stuff on the first call to {@link run}.
+ *
+ * Handles `--require` and `--ui`.  Does _not_ handle `--reporter`,
+ * as only the `Buffered` reporter is used.
+ *
+ * **This function only runs once per worker**; it overwrites itself with a no-op
+ * before returning.
+ *
+ * @param {Options} argv - Command-line options
+ */
+let bootstrap = async argv => {
+  // globalSetup and globalTeardown do not run in workers
+  const plugins = await handleRequires(argv.require, {
+    ignoredPlugins: ['mochaGlobalSetup', 'mochaGlobalTeardown']
+  });
+  validateLegacyPlugin(argv, 'ui', Mocha.interfaces);
+
+  rootHooks = plugins.rootHooks;
+  bootstrap = () => {};
+  debug('bootstrap(): finished with args: %O', argv);
+};
+
+/**
+ * Runs a single test file in a worker thread.
+ * @param {string} filepath - Filepath of test file
+ * @param {string} [serializedOptions] - **Serialized** options. This string will be eval'd!
+ * @see https://npm.im/serialize-javascript
+ * @returns {Promise<{failures: number, events: BufferedEvent[]}>} - Test
+ * failure count and list of events.
+ */
+async function run(filepath, serializedOptions = '{}') {
+  if (!filepath) {
+    throw createInvalidArgumentTypeError(
+      'Expected a non-empty "filepath" argument',
+      'file',
+      'string'
+    );
+  }
+
+  debug('run(): running test file %s', filepath);
+
+  if (typeof serializedOptions !== 'string') {
+    throw createInvalidArgumentTypeError(
+      'run() expects second parameter to be a string which was serialized by the `serialize-javascript` module',
+      'serializedOptions',
+      'string'
+    );
+  }
+  let argv;
+  try {
+    // eslint-disable-next-line no-eval
+    argv = eval('(' + serializedOptions + ')');
+  } catch (err) {
+    throw createInvalidArgumentValueError(
+      'run() was unable to deserialize the options',
+      'serializedOptions',
+      serializedOptions
+    );
+  }
+
+  const opts = Object.assign({ui: 'bdd'}, argv, {
+    // if this was true, it would cause infinite recursion.
+    parallel: false,
+    // this doesn't work in parallel mode
+    forbidOnly: true,
+    // it's useful for a Mocha instance to know if it's running in a worker process.
+    isWorker: true
+  });
+
+  await bootstrap(opts);
+
+  opts.rootHooks = rootHooks;
+
+  const mocha = new Mocha(opts).addFile(filepath);
+
+  try {
+    await mocha.loadFilesAsync();
+  } catch (err) {
+    debug('run(): could not load file %s: %s', filepath, err);
+    throw err;
+  }
+
+  return new Promise((resolve, reject) => {
+    let debugInterval;
+    /* istanbul ignore next */
+    if (isDebugEnabled) {
+      debugInterval = setInterval(() => {
+        debug('run(): still running %s...', filepath);
+      }, 5000).unref();
+    }
+    mocha.run(result => {
+      // Runner adds these; if we don't remove them, we'll get a leak.
+      process.removeAllListeners('uncaughtException');
+      process.removeAllListeners('unhandledRejection');
+
+      try {
+        const serialized = serialize(result);
+        debug(
+          'run(): completed run with %d test failures; returning to main process',
+          typeof result.failures === 'number' ? result.failures : 0
+        );
+        resolve(serialized);
+      } catch (err) {
+        // TODO: figure out exactly what the sad path looks like here.
+        // rejection should only happen if an error is "unrecoverable"
+        debug('run(): serialization failed; rejecting: %O', err);
+        reject(err);
+      } finally {
+        clearInterval(debugInterval);
+      }
+    });
+  });
+}
+
+// this registers the `run` function.
+workerpool.worker({run});
+
+debug('started worker process');
+
+// for testing
+exports.run = run;