Create Unit tests for the frontend

[leticiaarj]

Perform unit tests on the frontend project, having code coverage and possible error analysis.

Tasks

• Test as many components and methods as possible.
• Check the return of each test and signal the team about possible errors.
• Run the tests using the instructions contained here: https://github.com/lappis-unb/BotFlow.

Acceptance criteria

• The tests are working.
• The project is running.

[leticiaarj]

Derived from the issue #146.