使用“异步等待”模式时，Mocha单元测试尚未完成

Question

Assume the following class in TypeScript:

class MongoDbContext implements IMongoDbContext {
    private connectionString : string;
    private databaseName : string;
    private database : Db;
    public constructor (connectionString : string, databaseName : string) {
        this.connectionString = connectionString;
        this.databaseName = databaseName;
    }

    public async initializeAsync () : Promise<MongoDbContext> {
        // Create a client that represents a connection with the 'MongoDB' server and get a reference to the database.
        var client = await MongoClient.connect(this.connectionString, { useNewUrlParser: true });
        this.database = await client.db(this.databaseName);

        return this;
    }
}

Now, I want to test if an exception is thrown when I'm trying to connect to an unexisting MongoDB server, this is done with the following integration test:

it('Throws when a connection to the database server could not be made.', async () => {
    // Arrange.
    var exceptionThrowed : boolean = false;
    var mongoDbContext = new MongoDbContext('mongodb://127.0.0.1:20000/', 'databaseName');

    // Act.
    try { await mongoDbContext.initializeAsync(); }
    catch (error) { exceptionThrowed = true; }
    finally {
        // Assert.
        expect(exceptionThrowed).to.be.true;
    }
}).timeout(5000);

When I run this unit test, my CMD window doesn't print a summary. It seems that it's hanging somewhere.

What am I'm doing wrong in this case?

Kind regards,

Answer 1

I've managed to find the issue. It seems that I must close my 'MongoClient' connection for Mocha to quit correctly.

So, I've added an extra method

public async closeAsync () : Promise<void> {
    await this.client.close();
}

This method is called after each test.