DELETE /instances/{instancesId} endpoint throws an error even after removing the instance from the database

[dmahajan980]

While running some tests for the DELETE /instances/{instancesId} the app throws the following error:

On observing the database, the instance for which the request was made seemed to have been removed successfully from the database.

I think that we are trying to store the no of items removed from the database inside of n_removed which seems to be done in an incorrect manner. Because when I log the info object to the console, the console shows the following key-value pairs:

[yochannah]

hey @dmahajan980!

Could you perhaps set up a minimal set of lines to reproduce this? e.g. create an instance then delete it, so we can try copying/pasting this?

(this would also make a great unit test!)

[dmahajan980]

Hi @yochannah I have written a test case for this while writing the tests for issue #118
The above screenshot is a result of that. However the test code pertaining to this issue is:

const request = require('supertest');
const app = require('../app');
const User = require('../models/user');
const Instance = require('../models/instance');

const userOne = {
    user: 'dmahajan98',
    password: 'asdfghj'
};

const setupDatabase = async () => {  
    // Clear the test-database
    await Instance.deleteMany();
    await User.deleteMany();
    
    // Create a new user
    await new User(userOne).save();
};

beforeAll(setupDatabase);

const flyMine = {
    "name": "FlyMine",
    "namespace": "flymine",
    "neighbours": [
      "MODs"
    ],
    "organisms": [
      "Drosophila"
    ],
    "url": "http://www.flymine.org/query",
    "description": "FlyMine is an integrated database of genomic, expression and protein data for Drosophila, Anopheles and C. elegans",
    "location": {
      "latitude": "52.2003399",
      "longitude": "0.120109"
    },
    "twitter": "@intermineorg"
};

test('POST /instances : Should add an instance to the InterMine Registry', async () => {
    await request(app).post('/service/instances/')
        .auth(userOne.user, userOne.password)
        .send(flyMine)
        .expect(201);
});

test('DELETE /instances : Should delete the given InterMine Registry instance only', async () => {
    await request(app).delete('/service/instances/1')
        .auth(userOne.user, userOne.password)
        .send()
        .expect(200);
});

Written using jest and to be placed in the tests/ directory. Please let me know if I should send the code in some other way or if I got you wrong.

[dmahajan980]

@yochannah I ran the above test file and by modifying the DELETE router code at line no. 107, it seems to work fine.
Initially one of the test case fails as expected:

This is the currently existing code for the DELETE /instances/{instancesId} endpoint:

Notice when I simply change the code on line no. 107 as follows

This code passes both the above mentioned test cases as shown below: