Mocking & Mockito

For the final blog entry for this class, I decided to cover a topic that I’ve had personal experience with but wanted to review for further review and understanding, mocking and specifically, mockito. I found an article on toptal.com by Ivan Pavlov about mockito that is a guide for everyday use of the tool, exactly what I was looking for! The article has sections that includes some in depth analysis that could likely be used as a more in depth documentation for several aspects of mockito. The article also includes some insight into what mocks and spies are in the context of testing, unit testing specifically as well as some examples of the mockito tool in action.

For unit tests, we are testing the smallest unit of code possible for validity. The article states that the dependencies are not actually needed because we can create empty implementations of an interface for specific scenarios known as stubs. A stub is another kind of test double, along with mocks and spies, which are the two test doubles relevant to mockito. According to the article “mocking for unit testing is when you create an object that implements the behavior of areal subsystem in controlled ways.” They basically serve as a replacement for a dependency in a unit test. Mockito is used to create mocks, where you can tell mockito what you want to do when a method is called on a mocked object.

A spy for unit testing is another test double used by mockito. A spy, unlike a mock, requires a non-mocked instance to “spy on”. The spy “delegates all method calls to the real object and records what method was called and with what parameters”. It works as you would expect a spy to, it spies on the instance.  In general, mocks are more useful than the spy as they require no real implementation of the dependency as the spy does. The spy is also an indicator that a class is doing too much, “thus violating the single responsibility principle” of clean code.

Mocking with mockito can be used in a situation where you want to test that an object is being assigned a specific value when a method is called on it and certain parameters are met. A mock does not require the implementation of the methods to be written yet as you can assign values when a method is called by the power of mockito. This is why mockito is such a popular testing tool and mocking is such a popular testing strategy, and why I’ll continue to utilize it whenever relevant.

Link to original article: https://www.toptal.com/java/a-guide-to-everyday-mockito

 

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Boundary Value Testing

For this week’s blog post, I wanted to cover a topic that we covered earlier this semester, boundary value testing. I found an article on seemingly my go to site for articles for this blog, guru99. The article has several sections including a brief definition on what boundary testing is, as well as a definition of what equivalent class partitioning is and the relationship between the two. There are also a couple of examples and an analysis section that explains why we should use equivalence and boundary testing.

The article describes boundary testing as “the process of testing between extreme ends of boundaries between partitions of the input values.” These extreme values include the lower and upper bounds, or the minimum and maximum acceptable values for a given variable. For boundary testing, you need more than just the minimum and maximum values though. For the actual testing, you need a value that is just above the minimum, a nominal value that lies somewhere in the middle of the range, and a value that is just below the maximum value.

Equivalent class partitioning is explained by the article as “a black box technique (code is not visible to tester) which can be applied to all levels of testing.” It also states that when using equivalent class partitioning, “you divide the set of test condition into a partition that can be considered the same”.  This may sound a bit confusing but it is actually pretty simple. The article uses an example of a ticket system where values 1-10 are the only acceptable values and values 11-99 are invalid. You could break up this set of numbers into two different equivalent class partitions and then returning back to our boundary testing concept, we would test values like 0, 1, 5, 9, and 10.

The best part about boundary testing is that because it is a form of black box testing, you do not need to see how the actual code works. You only need to know the specifications for the valid and invalid numbers. Another reason to use boundary testing is that it eliminates the need for testing every value and thus, minimizes the tests needed. I have and will continue to utilize this testing strategy throughout my software engineering career.

Link to original article: https://www.guru99.com/equivalence-partitioning-boundary-value-analysis.html