Task
Modern applications can have complex internal architectures and often implement intricate behavior scenarios.
Moreover, such systems are constantly evolving. With each new commit, defects are fixed and new features are added, thereby increasing the complexity of the source code.
Complexity
Simply put, complexity can be described as a factor affecting the time required to complete tasks in a project. The more complex the project, the more time will be spent on task execution.
It is not uncommon for the execution time of only certain tasks to increase.
For example, in a project with a large amount of duplication, it is easy to add new functionality. However, changing existing functionality will be much more difficult.
This distribution is directly dependent on the chosen application architecture.
Refactoring
Developers, recognizing this trend, take measures to control software complexity.
One such measure is refactoring.
Refactoring is the process of changing a program's source code without altering its observable behavior.
Tests
The challenge lies in simplifying the system without causing regression.
Regression is a phenomenon in which the system loses its expected observable behavior.
Here, tests come to the rescue. Their primary purpose is to protect against regression, but this is not their only role.
Tests are programs that verify the properties and behaviors of another program.
Let's examine the problems that arise when testing applications.