Legacy Application Testing Without Documentation

Legacy Application Testing Without Documentation

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Today, legacy applications comprise more than 70% of the total corporate business systems. However, such applications are highly rigid and fragile in nature because of which most companies spend more than half of their IT budget on maintaining these legacy systems.

Legacy System

It is often considered a pejorative system that refers to a system that is outdated or needs replacement. It could be any system that has been inherited from an older version or is not linked to the Internet. You can also term an organization’s inactive application as a Legacy system.

Building a legacy application is no overnight task, as they are built over the years. Today, most of the organizations hold their business logic in such applications; however, the exact business process is known to very few of the employees. The situation becomes more challenging and complex, when such legacies are not documented properly. In spite of all these, most companies hesitate to upgrade their legacy applications, as they provide a longer stability.

However, even if one thinks about upgrading or replacing the legacy systems, there are tremendous risks and concerns associated with it. It requires a considerable amount of time along with a strong migration and re-engineering techniques to implement any changes. Moreover, testing and maintaining them during these situations is crucial. If there are many users involved and they do not feel the need for a drastic change, the companies consider the application to be quite stable and prefer using them.

Legacy Testing Without Documentation

Legacy applications are often delivered based on a particular business need. Such applications are not properly documented, as they may not be relevant in the future. This inefficiency adds a huge maintenance costs for many legacy systems. In some cases, even if the documents are available, they are just in the form of source code or prove to be insufficient.


There are many complications involved in testing such applications while upgrading them. Moreover, the complexity increases with no documentation. Some of the intricacies are mentioned below.


In order to ensure a stable release of an application, there must be a well-designed Regression Suite. You can follow some of the best practices to maximize the coverage of Regression Suite.

Testing Based on Dependencies

A slightest of change is enough for impacting the multiple modules or integration systems due to the blend of multiple modules and integration points. With dependency based testing, it requires minimum effort to ensure maximum coverage for the Regression Suite. In addition, it helps in the following ways:

You can always use any dependency driven testing tool to cover all the areas that might get impacted. A dependency driven testing tool can provide the following advantages:

Note: User must have a detailed knowledge of the application and the changes for which the Regression Suite is built.


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