Creating Unit Tests for COBOL Programs

Unit testing is a critical practice in software development. It involves testing individual components or functions of a program to ensure they perform as expected. In COBOL, implementing unit tests can significantly enhance code quality, maintainability, and overall reliability. This article provides a comprehensive guide on how to write effective unit tests for your COBOL programs, along with best practices and tools that can help streamline the testing process.

Understanding the Importance of Unit Testing in COBOL

Before diving into the specifics of writing unit tests, it's essential to understand why they are vital:

Early Bug Detection: Unit tests help identify bugs early in the development process, reducing the cost and effort required to fix them later.
Code Refactoring: If you plan to refactor your COBOL code, having a solid suite of unit tests ensures that you can make changes safely without inadvertently introducing new bugs.
Documentation: Well-written unit tests serve as a form of documentation. They clarify how functions are supposed to work and highlight edge cases.
Confidence in Deployment: When unit tests are in place, developers can deploy code changes with more confidence, knowing that existing functionality is verified.

Setting Up Your COBOL Testing Environment

To begin unit testing in COBOL, you’ll need a suitable environment and some tools. The following steps can help you set up:

1. Choose a COBOL Compiler

You need to have a COBOL compiler that supports the features you wish to test. Popular options include:

Micro Focus Visual COBOL
GnuCOBOL
IBM Enterprise COBOL

Make sure your development environment is properly configured and that you have command line access to compile your COBOL programs.

2. Select a Testing Framework

There are several testing frameworks available for COBOL. While they may not be as popular as those in other languages, they can still facilitate writing and executing unit tests. Some options include:

COBOL-IT: A portable and open-source COBOL environment that includes testing features.
OpenCOBOL Testing Framework: This framework provides simple syntax for defining tests.

Choose a framework that aligns with your project requirements and coding practices.

Writing Unit Tests in COBOL

Let’s look at how to write unit tests for COBOL programs step-by-step.

Step 1: Define Your Test Cases

Define what you want to test before writing the actual tests. Common test cases include:

Testing standard function outputs based on input values
Checking for error handling in edge cases
Verifying that business rules are correctly implemented

Step 2: Create a Test Program

You can create a separate COBOL program for your tests or integrate the tests within your existing program. Here’s a basic example of a test program:

       IDENTIFICATION DIVISION.
       PROGRAM-ID. TestExample.

       ENVIRONMENT DIVISION.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 Test-Result  PIC X(10).
       01 Expected-Result PIC X(10).

       PROCEDURE DIVISION.
       MAIN-PARA.
           PERFORM Test-Sample-Function.
           DISPLAY "All tests completed.".

       Test-Sample-Function.
           MOVE "SUCCESS" TO Test-Result.
           MOVE "SUCCESS" TO Expected-Result.

           IF Test-Result = Expected-Result THEN
               DISPLAY "Test Passed." 
           ELSE
               DISPLAY "Test Failed."   
           END-IF.
           .

This program sets up a simple test case where it compares the Test-Result with the Expected-Result. You can expand this approach to include multiple tests for various functions.

Step 3: Implement the Functions Being Tested

Let’s say you have a function that performs calculations. You need to ensure this function can be called from your test program:

       IDENTIFICATION DIVISION.
       PROGRAM-ID. SampleFunction.

       ENVIRONMENT DIVISION.
       DATA DIVISION.
       LINKAGE SECTION.
       01 Input-Value1 PIC 9(5).
       01 Input-Value2 PIC 9(5).
       01 Output-Value PIC 9(5).

       PROCEDURE DIVISION USING Input-Value1 Input-Value2 RETURNING Output-Value.
           COMPUTE Output-Value = Input-Value1 + Input-Value2.
       END-PROCEDURE.

Step 4: Run Your Tests

Compile your test program and execute it. You should see the output indicating whether your tests passed or failed. This can be done using the typical command-line approach based on your chosen COBOL compiler.

Step 5: Assess and Iterate

After running your tests, assess the results. If any tests fail, analyze the failures. Common actions include debugging the function behavior, adjusting test cases, or modifying implementation bugs. It’s crucial to iterate on your tests continuously as the codebase grows or changes.

Best Practices for Unit Testing in COBOL

To make your unit testing process effective, consider the following best practices:

Keep Tests Small and Focused: Each test should verify a single aspect of the behavior of the function. This makes it easier to identify what is broken when a test fails.
Name Tests Meaningfully: Use descriptive names for your test cases that indicate what functionality is being tested. This enhances readability and maintainability.
Automate Testing Where Possible: If you automate your test execution, you can run your unit tests frequently, such as during integration or before a deployment.
Maintain a Testing Schedule: Regularly update and run your tests as your program evolves. This will help catch regressions early.
Document Your Test Cases: Clearly comment your test cases to explain the logic, inputs, and expected outputs. This helps your future self and your colleagues understand your thought process.

Conclusion

Unit testing is an essential part of the development lifecycle, even in older programming languages like COBOL. By implementing effective unit tests, you can ensure that your COBOL programs maintain high quality, remain bug-free, and reflect reliable business logic. With the guidance provided in this article, you are now well equipped to write your own unit tests, helping to elevate the reliability and durability of your COBOL code. Happy testing!

Programming - COBOL