As developers, we usually aim at working on challenging problems, trying to navigate through the complex connections, and coming up with a solution. But how many times do we care to look at all the possible ways through which our code can fail to provide the expected outcome? As much as it is hard to try to break something that we as developers have written ourselves, it forms one of the most important aspects of the development cycle.

This is the time when testing becomes an important aspect of the development life cycle. The aim of application testing can be summed up by answering the following questions:

• Are the individual components in the code performing as per the expectations?
• Does the flow of the code from one component to another as is desired?
• Was the final outcome of the application the same that we thought of?
• Are there some deviations in the standard behavior?
• Did the application handle all the expected scenarios and provided a fail-safe over for the unexpected ones?

With the preceding questions answered, we are now able to define how well our application has been built and how robust the application is in case some unexpected input is given to the application. This results in various benefits, such as the following:

• Early detection of bugs: With the testing being a part of the development cycle itself and the individual components of the code base being subject to separate tests, we can ensure that a large number of bugs can be detected early in the development phase itself.
• Increased reliability: With the testing in place to detect the bugs early, we can see how much our application is reliable in generating accurate results for the expected set of inputs without causing trouble to the user.
• Robustness in check: No matter what we do, there will be cases when a user may input an incorrect set of inputs, and how our application responds to that is important. One of the aims of testing is to ensure that our application is able to handle the incorrect set of inputs without generating a crash or causing a major loss to the data.
• Reduced maintenance costs: When an application has undergone a thorough testing phase during its development and post-development phases, most of the critical bugs are already identified and fixed before the application is deployed in the production environment. This indirectly results in the reduction of maintenance costs due to the smaller number of hours required from the engineers trying to fire fight the issues that may arise due to failure in testing the behavior of the application when an unexpected input is provided.

For an enterprise-grade application, a thorough testing that starts early from the development phase itself will result in the users of the application having a pleasant time using the application. Thus they will be able to achieve more productive output instead of spending time dealing with how to handle a particular use case because the application doesn't handle it properly.

Now, we know why testing of the application is an important aspect. But is there just one kind of testing? What kind of application testing should a developer be doing before handing off the application to the quality engineering teams? Let's take a look.