Learning Kotlin is fun, but where to get started? One the of the best tutorials for newbies is at https://code.tutsplus.com/series/kotlin-from-scratch--cms-1209. Learn from scratch. To practice, download IntelliJ IDEA and work on Kotlin code anytime in it.
Good way for beginners to learn test driven programming in Eclipse for Java. See the tutorials here http://eclipsetutorial.sourceforge.net/totalbeginner.html.