Test Writing: Double Up

Created By: Chris Taylor

/ Version: 2023.6.0

Write a method, doubleUp, that accepts a list of Strings and returns a list of Strings where each String in the original list is concatenated with itself. You may assume that the list passed is not null and does not contain any null elements. Your solution must make use of a stream and at least one lambda expression.

• ["a", "b"] -> ["aa", "bb"]
• ["", "last"] -> ["", "lastlast"]

Test Design Challenge

You're challenge is to write tests for this problem described above.

• Provide a method named test that accepts no arguments and does not return a value.
• If the implementation of the class described above is incorrect, your test method should throw an exception.
• If it is correct, do not throw an exception.
• You may want to use Java's assert method