Hands-On Object-Oriented Programming with Kotlin

Testing exceptions

The set method of the ToDoStorage class can throw ToDoAlreadyExistException:

operator fun set(name: String, todo: ToDo): Boolean {    if (todos.contains(name)) {        throw ToDoAlreadyExistException()    }    todos[name] = todo    return true}

It is also important to make sure that this exception will be thrown when it is needed. For this, we can write one more test that checks whether ToDoAlreadyException is thrown when a user tries to store a todo with a key that already exists.

We need to add a dependency to the kotlintest library (https://github.com/kotlintest/kotlintest) to be able to use the shouldThrow function. After integrating this library, your dependencies section in the build.gradle file will look as follows:

dependencies ...