Lecture Code #
Code from this lecture available at https://github.com/Berkeley-CS61B/lectureCode-fa22/tree/main/lec3_testing.
Historical Live QA #
Why Test Code? In the real world, chances are you won’t have an autograder. When your code gets deployed into production, it is important that you know that it will work for simple cases as well as strange edge cases.
Test-Driven Development When provided an autograder, it is very easy to go “autograder happy”. Instead of actually understanding the spec and the requirements for a project, a student may write some base implementation, smash their code against the autograder, fix some parts, and repeat until a test is passed. This process tends to be a bit lengthy and really is not the best use of time. We will introduce a new programming method, Test-Driven Development (TDD), where the programmer writes the tests for a function BEFORE the actual function is written. Since unit tests are written before the function is, it becomes much easier to isolate errors in your code. Additionally, writing unit test requires that you have a relatively solid understanding of the task that you are undertaking. A drawback of this method is that it can be easy to forget to test how functions interact with each other!
JUnit Tests JUnit is a package that is used to debug programs
in Java. An example function that comes from JUnit is
assertEquals(expected, actual). This function asserts that expected and
actual have the same value. There are a bunch of other
JUnit functions such as
When writing JUnit tests, it is good practice to write ‘@Test’ above the function that is testing. This allows for all your test methods to be run non statically.
In general, is it good to write tests that test your entire program? How about for specific functions?
The check-in exercises, linked here
When we say that test methods which have been annotated with
can be run non statically, what does that mean?
Write a testing method as outlined in the comments in this java file: https://github.com/Berkeley-CS61B/lectureCode-fa22/blob/main/lec3_testing/TestingPractice.java
When do you want to write your tests? Is testing a one time thing? Is there one correct way to test? How can you determine the pros and cons of any one specific testing approach?