Db name different for each test file about jest-mongodb

[vassbence]

The readme examples were changed in this PR but the Jest website still has parallel friendly setup examples.

I believe the examples should be parallel friendly as most people just grab it and go, but later face some unexpected race conditions when for example multiple test files clear the db in parallel.

(setting db explicitly to an unique string in beforeAll mitigates the race conditions)

@vladgolubev what's your opinion on this?

[sbland]

I had to hack the process.env.MONGO_URL variable as below to get this to work
const full_url = DB_NAME ? MONGO_URL.split('/').slice(0, -1).join('/') + '/' + DB_NAME : MONGO_URL;
This converted mongodb://127.0.0.1:41185/1605a3c8-5a40-4d93-880a-bb186f222db7 to mongodb://127.0.0.1:41185/DB_NAME. I then just altered DB_NAME for each test file.

[matthyy]

I agree with you, the variable "MONGO_URI" does not change over different test suites but "MONGO_DB_NAME" variable changes. That's why, the document mentions two steps :

1. connect to instance and the default database.
2. connect to a new database named "MONGO_DB_NAME" .

connection = await MongoClient.connect(process.env.MONGO_URL, {
      useNewUrlParser: true,
      useUnifiedTopology: true
    });
 db = await connection.db();

To make it work, you have to do this : (in order to connect to another database)

connection = await MongoClient.connect(process.env.MONGO_URL, {
      useNewUrlParser: true,
      useUnifiedTopology: true
    });
await connection.db(global.__MONGO_DB_NAME__)

When using mongoose, you can do the following

mongoose.connect(uri: global.__MONGO_URI__, {dbName: global.__MONGO_DB_NAME__}

I am volunteer to make a PR. To me, there are two options:

1. update documentation with above examples
2. when building MONGO_URI variable in environment.js, we change database name by using "global.MONGO_DB_NAME"

[djaircarvalho]

Hi @jardakotesovec, the jest doc has a slightly different example. Maybe you can have some luck:

beforeAll(async () => {
    connection = await MongoClient.connect(global.__MONGO_URI__, {
      useNewUrlParser: true,
    });
    db = await connection.db(global.__MONGO_DB_NAME__);
  });

[danny-does-stuff]

With a config like this

mongodbMemoryServerOptions: {
	instance: {},
	binary: {
		version: '4.0.3', // Version of MongoDB
		skipMD5: true,
	},
	autoStart: false,
},

where instance is set to {}, I was able to get a unique mongo url for each test by using this function inspired by the comment by @sbland above

function getMongoUrl() {
	return (
		process.env.MONGO_URL.split('/')
			.slice(0, -1)
			.join('/') + `/${global.__MONGO_DB_NAME__}`
	)
}