fix: wait for mongod process to exit before removing its files (#27)

* wait for mongodb process to exit before removing its files

* feat(MongoInstance): add kill(), getPid() methods. Small refactoring.

* test(MongoInstance): check async kill()

* expect mongod to be running before killing it

Author: gvuyk

src/MongoMemoryServer.js

@@ -36,6 +36,7 @@ export type MongoInstanceDataT = {
   dbName: string,
   uri: string,
   storageEngine: string,
+  instance: MongoInstance,
   childProcess: ChildProcess,
   tmpDir?: {
     name: string,
@@ -125,7 +126,7 @@ export default class MongoMemoryServer {
 
     // Download if not exists mongo binaries in ~/.mongodb-prebuilt
     // After that startup MongoDB instance
-    const childProcess = await MongoInstance.run({
+    const instance = await MongoInstance.run({
       instance: {
         port: data.port,
         storageEngine: data.storageEngine,
@@ -136,7 +137,8 @@ export default class MongoMemoryServer {
       spawn: this.opts.spawn,
       debug: this.debug,
     });
-    data.childProcess = childProcess;
+    data.instance = instance;
+    data.childProcess = instance.childProcess;
     data.tmpDir = tmpDir;
 
     return data;
@@ -147,7 +149,10 @@ export default class MongoMemoryServer {
 
     if (childProcess && childProcess.kill) {
       this.debug(`Shutdown MongoDB server on port ${port} with pid ${childProcess.pid}`);
-      childProcess.kill();
+      await new Promise(resolve => {
+        childProcess.once(`exit`, resolve);
+        childProcess.kill();
+      });
     }
 
     if (tmpDir) {

src/util/MongoInstance.js

@@ -43,7 +43,7 @@ export default class MongodbInstance {
   instanceReady: Function;
   instanceFailed: Function;
 
-  static run(opts: MongodOps): Promise<ChildProcess> {
+  static run(opts: MongodOps): Promise<MongodbInstance> {
     const instance = new this(opts);
     return instance.run();
   }
@@ -85,7 +85,7 @@ export default class MongodbInstance {
     return result;
   }
 
-  async run(): Promise<ChildProcess> {
+  async run(): Promise<MongodbInstance> {
     const launch = new Promise((resolve, reject) => {
       this.instanceReady = () => {
         this.debug('MongodbInstance: is ready!');
@@ -99,14 +99,28 @@ export default class MongodbInstance {
     });
 
     const mongoBin = await MongoBinary.getPath(this.opts.binary);
-    this.childProcess = this.launchMongod(mongoBin);
-    this.killerProcess = this.launchKiller(process.pid, this.childProcess.pid);
+    this.childProcess = this._launchMongod(mongoBin);
+    this.killerProcess = this._launchKiller(process.pid, this.childProcess.pid);
 
     await launch;
-    return this.childProcess;
+    return this;
   }
 
-  launchMongod(mongoBin: string): ChildProcess {
+  async kill(): Promise<MongodbInstance> {
+    if (this.childProcess && !this.childProcess.killed) {
+      await new Promise(resolve => {
+        this.childProcess.once(`exit`, resolve);
+        this.childProcess.kill();
+      });
+    }
+    return this;
+  }
+
+  getPid(): ?number {
+    return this.childProcess ? this.childProcess.pid : undefined;
+  }
+
+  _launchMongod(mongoBin: string): ChildProcess {
     const spawnOpts = this.opts.spawn || {};
     if (!spawnOpts.stdio) spawnOpts.stdio = 'pipe';
     const childProcess = spawnChild(mongoBin, this.prepareCommandArgs(), spawnOpts);
@@ -118,7 +132,7 @@ export default class MongodbInstance {
     return childProcess;
   }
 
-  launchKiller(parentPid: number, childPid: number): ChildProcess {
+  _launchKiller(parentPid: number, childPid: number): ChildProcess {
     // spawn process which kills itself and mongo process if current process is dead
     const killer = spawnChild(
       process.argv[0],

src/util/__tests__/MongoInstance-test.js

@@ -41,8 +41,9 @@ describe('MongoInstance', () => {
       binary: { version: '3.4.4' },
     });
 
-    expect(mongod.pid).toBeGreaterThan(0);
-    mongod.kill();
+    expect(mongod.getPid()).toBeGreaterThan(0);
+
+    await mongod.kill();
   });
 
   it('should throw error if port is busy', async () => {
@@ -58,6 +59,27 @@ describe('MongoInstance', () => {
       })
     ).rejects.toBeDefined();
 
-    mongod.kill();
+    await mongod.kill();
+  });
+
+  it('should await while mongo is killed', async () => {
+    const mongod = await MongoInstance.run({
+      instance: { port: 27445, dbPath: tmpDir.name },
+      binary: { version: '3.4.4' },
+    });
+    const pid: any = mongod.getPid();
+    expect(pid).toBeGreaterThan(0);
+
+    function isPidRunning(p: number) {
+      try {
+        return process.kill(p, 0);
+      } catch (e) {
+        return e.code === 'EPERM';
+      }
+    }
+
+    expect(isPidRunning(pid)).toBeTruthy();
+    await mongod.kill();
+    expect(isPidRunning(pid)).toBeFalsy();
   });
 });