Add unit tests for user routes

[IsaacCheng9]

Changes

• Created a file, users.test.js for unit tests for the user routes.
• Changed the endpoint to create a user to adhere to REST API conventions (POST /users/add -> POST /users).
• Added an endpoint to get a user by their username: GET /users/:username
• Added an endpoint to delete a user by their username: DELETE /users/:username

Note that we currently have open handles that we need to resolve.

Related Issues

• Issue #32
  • This is the first step of the issue – further work is required for debts.js and expenses.js.

Testing

isaac@MBP16 server % npm test

> server@1.0.0 test
> jest --forceExit

  console.log
    Server is running at port 3001.

      at Server.log (app.js:44:11)

  console.log
    Connected successfully.

      at NativeConnection.log (app.js:38:11)

 PASS  routes/users.test.js
  ✓ GET /users (684 ms)
  ✓ POST /users (141 ms)
  ✓ GET /users/:username (29 ms)
  ✓ DELETE /users/:username (37 ms)

Test Suites: 1 passed, 1 total
Tests:       4 passed, 4 total
Snapshots:   0 total
Time:        1.657 s
Ran all test suites.
Force exiting Jest: Have you considered using `--detectOpenHandles` to detect async operations that kept running after all tests finished?

[gkSideProjects]

Looks great!