In the post Mock? What, When, How? by Lovis Möller, he discusses mocking and when to use it. Mocking is a strategy used in test-driven development where a mock object is created to test the interactions and dependencies this class has with other classes. Lovis talks about looking at his own and other people’s code and determines some situations in which he would use or would not use mocking, and why he would or would not use it.

Lovis first point is that you should only mock types that are internal to your program, and avoid mocking external types. External types may have dependencies of their own that you don’t know about, and could change in a later version of the code. Avoiding mocking makes your code more adaptable for future versions. The next thing Lovis recommends is that you do not mock values. If you mock values, you aren’t actually testing any useful part of the code. Lovin states:

“Mocking is a technique that is used to make the relationships and interactions between objects visible.”

The last big example Lovis gives is to not to mock concrete classes. The example and associated code he gives makes it pretty clear, as the result depends on a method that has not been covered by the mocked methods within the code. It is easy to see how this could get out of hand if you had to covered each method of a mocked class for your mock testing.

I had a lot of trouble understanding mocking and when you would want to use and and why before reading this post. Although it is still a difficult concept to understand why we are making these mock objects, seeing circumstances in which you would or wouldn’t want to use mocking, and alternatives to mocking make it a little easier to see how it is testing a program and why it is a useful concept. The quote I selected above made this even more apparent to me. Mocking isn’t testing the implementation or your program so much as the relationships between objects and their methods and how they interact.

The post Are Patterns like Mummies? by Michael Stal discusses the patterns from the book Design Patterns: Elements of Reusable Object-Oriented Software by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides, otherwise known as the Gang of Four. This is the book containing the design patterns that we have been studying in class. He discusses how when the book first came out how groundbreaking it was for the software engineering community. Michael also discusses how after the Gang of Four book came out, there wasn’t anything that came after it that had quite as much impact. Michael questions whether more patterns exist, and whether they’ve been documented, or if the book contains most if not all of the worthwhile software design patterns.

The Gang of Four design patterns are basically ways to organize and structure your code in a certain way that solves certain issues you would run into and has certain advantages that can lend themselves to whatever you are doing. The author’s break down the design patterns into three different categories, which are:

• Creational
• Structural
• Behavioral

Creational patterns deal with the creation of objects, structural patterns are executed through inheritance and interfaces, and behavioral patterns concern themselves with the communication between objects. There are several design patterns within each of these categories.

It is interesting to think about if the patterns covered within this book are the only design patterns (or at least the strongest) within software design. This means every large-scale program is ultimately composed of many components using only the design patterns contained within this book. Is there even a need to define more software design patterns, or can any given program or implementation issue be solved with the patterns found within the Gang of Four book?

I agree with Michael’s closing thoughts about design patterns, I think using them correctly and consistently leads to much more functional code and encourages best practices among software engineers. Whether or not there are more design patterns to uncover, or if we have reached our limit, the patterns we are aware of are still important to use to make communication between software engineers easier.