Cobol Check

Cobol Check provides fine-grained unit testing/checking for Cobol at the same conceptual level of detail as unit testing frameworks for other languages, such as Python, Ruby, C#, and Java.

The project is part of the Open Mainframe Project, an initiative to collect and manage Open Source resources supporting the IBM zSeries platform.

Vicom Infinity is kindly providing access to a z/OS system for testing.



  • CobolCheck v 0.0.1 24 Feb 21
  • This is a very early version. We would appreciate people trying it out and providing feedback. It is not recommended for production use at this time.

See the User Guide for installation instructions and other details.

Immediate Needs

As of Februrary 2021 we could use help with:
– review of localized messages by native speakers and creation of additional localized message files


The industry is experiencing a resurgence in interest in Cobol, both to support existing applications and to take advantage of the continuing evolution of the zSeries platform. Commercial unit testing tools for Cobol are able to exercise code at the level of a whole load module, but cannot exercise individual Cobol paragraphs in isolation. That limitation means we cannot achieve the same degree of granularity in microtests as we can when working in other languages, such as Java, Kotlin, C#, Python, or Ruby.

Please see the cobol-check project on github for more information.