feat: add binary.skipMD5 and MONGOMS_SKIP_MD5_CHECK environment options

* fix: add error handling in postinstall

* feat: add MONGOMS_SKIP_MD5_CHECK for skipping md5 check

* refactor: add return type in checkMd5 signature

Response to the comment #114 (comment)

* refactor: add checkMD5 parameter to the MongoBinaryDownload constructor

For details see #114 (comment)

* refactor: style changes and function renaming

For details see #114 (comment)
and nodkz comment after approving pull request

Author: dimitriylol

README.md

@@ -62,6 +62,7 @@ const mongod = new MongoMemoryServer({
     platform?: string, // by default os.platform()
     arch?: string, // by default os.arch()
     debug?: boolean, // by default false
+    skipMD5?: boolean, // by default false OR process.env.MONGOMS_SKIP_MD5_CHECK
   },
   debug?: boolean, // by default false
   autoStart?: boolean, // by default true
@@ -76,6 +77,8 @@ MONGOMS_VERSION=3
 MONGOMS_DEBUG=1 # also available case-insensitive values: "on" "yes" "true"
 MONGOMS_DOWNLOAD_MIRROR=url # your mirror url to download the mongodb binary
 MONGOMS_DISABLE_POSTINSTALL=1 # if you want to skip download binaries on `npm i` command
+MONGOMS_SKIP_MD5_CHECK=1 # if you want to skip MD5 check of downloaded binary.
+# Passed constructor parameter `binary.skipMD5` has higher priority.
 ```
 
 ### Replica Set start:

postinstall.js

@@ -27,6 +27,11 @@ if (isModuleExists('./lib/util/MongoBinary')) {
   console.log('mongodb-memory-server: checking MongoDB binaries cache...');
   MongoBinary.getPath({}).then(binPath => {
     console.log(`mongodb-memory-server: binary path is ${binPath}`);
+  })
+  .catch((err) => {
+    console.log(`failed to download/install MongoDB binaries. The error:
+${err}`)
+    process.exit(1)
   });
 } else {
   console.log("Can't resolve MongoBinary module");

src/util/MongoBinaryDownload.js

@@ -18,22 +18,38 @@ export type MongoBinaryDownloadOpts = {
   platform: string,
   arch: string,
   debug?: DebugPropT,
+  skipMD5?: boolean,
 };
 
 export default class MongoBinaryDownload {
   debug: DebugFn;
   dlProgress: DownloadProgressT;
 
+  skipMD5: boolean;
   downloadDir: string;
   arch: string;
   version: string;
   platform: string;
 
-  constructor({ platform, arch, downloadDir, version, debug }: $Shape<MongoBinaryDownloadOpts>) {
+  constructor({
+    platform,
+    arch,
+    downloadDir,
+    version,
+    skipMD5,
+    debug,
+  }: $Shape<MongoBinaryDownloadOpts>) {
     this.platform = platform || os.platform();
     this.arch = arch || os.arch();
     this.version = version || 'latest';
     this.downloadDir = path.resolve(downloadDir || 'mongodb-download');
+    if (skipMD5 === undefined) {
+      this.skipMD5 =
+        typeof process.env.MONGOMS_SKIP_MD5_CHECK === 'string' &&
+        ['1', 'on', 'yes', 'true'].indexOf(process.env.MONGOMS_SKIP_MD5_CHECK.toLowerCase()) !== -1;
+    } else {
+      this.skipMD5 = skipMD5;
+    }
     this.dlProgress = {
       current: 0,
       length: 0,
@@ -84,20 +100,24 @@ export default class MongoBinaryDownload {
     const downloadUrl = await mbdUrl.getDownloadUrl();
     const mongoDBArchive = await this.download(downloadUrl);
 
-    const mongoDBArchiveMd5 = await this.download(`${downloadUrl}.md5`);
-    await this.checkMd5(mongoDBArchiveMd5, mongoDBArchive);
+    await this.checkMD5(`${downloadUrl}.md5`, mongoDBArchive);
 
     return mongoDBArchive;
   }
 
-  async checkMd5(mongoDBArchiveMd5: string, mongoDBArchive: string) {
+  async checkMD5(urlForReferenceMD5: string, mongoDBArchive: string): Promise<?boolean> {
+    if (this.skipMD5) {
+      return undefined;
+    }
+    const mongoDBArchiveMd5 = await this.download(urlForReferenceMD5);
     const signatureContent = fs.readFileSync(mongoDBArchiveMd5).toString('UTF-8');
     const m = signatureContent.match(/(.*?)\s/);
     const md5Remote = m ? m[1] : null;
     const md5Local = md5File.sync(mongoDBArchive);
     if (md5Remote !== md5Local) {
       throw new Error('MongoBinaryDownload: md5 check is failed');
     }
+    return true;
   }
 
   async download(downloadUrl: string) {

src/util/__tests__/MongoBinaryDownload-test.js

@@ -1,8 +1,29 @@
 /* @flow */
 
+import fs from 'fs';
+import md5file from 'md5-file';
 import MongoBinaryDownload from '../MongoBinaryDownload';
 
+jest.mock('fs');
+jest.mock('md5-file');
+
 describe('MongoBinaryDownload', () => {
+  afterEach(() => {
+    delete process.env.MONGOMS_SKIP_MD5_CHECK;
+  });
+
+  it('skipMD5 attribute can be set via constructor parameter', () => {
+    expect(new MongoBinaryDownload({ skipMD5: true }).skipMD5).toBe(true);
+    expect(new MongoBinaryDownload({ skipMD5: false }).skipMD5).toBe(false);
+  });
+
+  it(`if skipMD5 input parameter is missing, then it checks 
+MONGOMS_SKIP_MD5_CHECK environment variable`, () => {
+    expect(new MongoBinaryDownload({}).skipMD5).toBe(false);
+    process.env.MONGOMS_SKIP_MD5_CHECK = '1';
+    expect(new MongoBinaryDownload({}).skipMD5).toBe(true);
+  });
+
   it('should use direct download', async () => {
     process.env['yarn_https-proxy'] = '';
     process.env.yarn_proxy = '';
@@ -34,4 +55,46 @@ describe('MongoBinaryDownload', () => {
     expect(callArg1.agent).toBeDefined();
     expect(callArg1.agent.options.href).toBe('http://user:pass@proxy:8080/');
   });
+
+  it(`checkMD5 returns true if md5 of downloaded mongoDBArchive is
+the same as in the reference result`, () => {
+    const someMd5 = 'md5';
+    fs.readFileSync.mockImplementationOnce(() => `${someMd5} fileName`);
+    md5file.sync.mockImplementationOnce(() => someMd5);
+    const mongoDBArchivePath = '/some/path';
+    const fileWithReferenceMd5 = '/another/path';
+    const du = new MongoBinaryDownload({});
+    // $FlowFixMe
+    du.download = jest.fn(() => Promise.resolve(fileWithReferenceMd5));
+    const urlToMongoDBArchivePath = 'some-url';
+    return du.checkMD5(urlToMongoDBArchivePath, mongoDBArchivePath).then(res => {
+      expect(res).toBe(true);
+      expect(du.download).toBeCalledWith(urlToMongoDBArchivePath);
+      expect(fs.readFileSync).toBeCalledWith(fileWithReferenceMd5);
+      expect(md5file.sync).toBeCalledWith(mongoDBArchivePath);
+    });
+  });
+
+  it(`checkMD5 throws an error if md5 of downloaded mongoDBArchive is NOT
+  the same as in the reference result`, () => {
+    fs.readFileSync.mockImplementationOnce(() => 'someMd5 fileName');
+    md5file.sync.mockImplementationOnce(() => 'anotherMd5');
+    const du = new MongoBinaryDownload({});
+    // $FlowFixMe
+    du.download = jest.fn(() => Promise.resolve(''));
+    expect(du.checkMD5('', '')).rejects.toMatchInlineSnapshot(
+      `[Error: MongoBinaryDownload: md5 check is failed]`
+    );
+  });
+
+  it('true value of skipMD5 attribute disables checkMD5 validation', () => {
+    expect.assertions(1);
+    fs.readFileSync.mockImplementationOnce(() => 'someMd5 fileName');
+    md5file.sync.mockImplementationOnce(() => 'anotherMd5');
+    const du = new MongoBinaryDownload({});
+    du.skipMD5 = true;
+    return du.checkMD5('', '').then(res => {
+      expect(res).toBe(undefined);
+    });
+  });
 });