Db name different for each test file

Hi, from Readme I was under impression that if I pass empty object to instance property I will get random db per file.

If I simply print out the global variables in every test file I am getting: One file:

process.env.MONGO_URL: mongodb://127.0.0.1:56925/3b97e130-dd09-440d-9937-a7442a421da7?
global.__MONGO_URI__: mongodb://127.0.0.1:56925/3b97e130-dd09-440d-9937-a7442a421da7?
global.__MONGO_DB_NAME__: 1ed20263-b27c-42c8-a800-805368f8fdb3

Second file:

process.env.MONGO_URL: mongodb://127.0.0.1:56925/3b97e130-dd09-440d-9937-a7442a421da7?
global.__MONGO_URI__: mongodb://127.0.0.1:56925/3b97e130-dd09-440d-9937-a7442a421da7?
global.__MONGO_DB_NAME__: e2eb11c0-c836-4849-a7fb-568a642e02bf

So its true that db name is random, but its same for all test files, which is not really that much useful. My expectation was that it would be unique db name per test file - interestingly thats what we get in MONGO_DB_NAME, but we still need to create sensible MONGO_URL from it, it seems.

Am I missing something?

[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?

[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”