feat(errors): add "StartBinaryFailedError"

Author: hasezoey

packages/mongodb-memory-server-core/src/util/MongoInstance.ts

@@ -7,6 +7,7 @@ import { lt } from 'semver';
 import { EventEmitter } from 'events';
 import { MongoClient, MongoNetworkError } from 'mongodb';
 import { promises as fspromises, constants } from 'fs';
+import { StartBinaryFailedError } from './errors';
 
 if (lt(process.version, '10.15.0')) {
   console.warn('Using NodeJS below 10.15.0');
@@ -391,7 +392,7 @@ export class MongoInstance extends EventEmitter implements ManagerBase {
     childProcess.on('error', this.errorHandler.bind(this));
 
     if (isNullOrUndefined(childProcess.pid)) {
-      throw new Error('Spawned Mongo Instance PID is undefined');
+      throw new StartBinaryFailedError(path.resolve(mongoBin));
     }
 
     this.emit(MongoInstanceEvents.instanceLaunched);

packages/mongodb-memory-server-core/src/util/__tests__/MongoInstance.test.ts

@@ -4,6 +4,7 @@ import * as dbUtil from '../utils';
 import MongodbInstance, { MongoInstanceEvents } from '../MongoInstance';
 import resolveConfig, { ResolveConfigVariables } from '../resolveConfig';
 import getPort from 'get-port';
+import { StartBinaryFailedError } from '../errors';
 
 jest.setTimeout(100000); // 10s
 tmp.setGracefulCleanup();
@@ -216,12 +217,14 @@ describe('MongodbInstance', () => {
 
   it('"_launchMongod" should throw an error if "mongodProcess.pid" is undefined', () => {
     const mongod = new MongodbInstance({ instance: { port: 0, dbPath: '' } }); // dummy values - they shouldnt matter
+    const mockBinary = 'thisShouldNotExist';
 
     try {
-      mongod._launchMongod('thisShouldNotExist');
+      mongod._launchMongod(mockBinary);
       fail('Expected "_launchMongod" to throw');
     } catch (err) {
-      expect(err.message).toEqual('Spawned Mongo Instance PID is undefined');
+      expect(err).toBeInstanceOf(StartBinaryFailedError);
+      expect(JSON.stringify(err)).toMatchSnapshot(); // this is to test all the custom values on the error
     }
   });
 

packages/mongodb-memory-server-core/src/util/__tests__/__snapshots__/MongoInstance.test.ts.snap

@@ -0,0 +1,3 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`MongodbInstance "_launchMongod" should throw an error if "mongodProcess.pid" is undefined 1`] = `"{\\"binary\\":\\"/projects/nodejs/mongodb-memory-server/packages/mongodb-memory-server-core/thisShouldNotExist\\"}"`;

packages/mongodb-memory-server-core/src/util/errors.ts

@@ -78,3 +78,9 @@ export class Md5CheckFailedError extends Error {
     super(`MD5 check failed! Binary MD5 is "${binarymd5}", Checkfile MD5 is "${checkfilemd5}"`);
   }
 }
+
+export class StartBinaryFailedError extends Error {
+  constructor(public binary: string) {
+    super(`Starting the Binary Failed (PID is undefined)! Binary: "${binary}"`);
+  }
+}