Automating SAS Tests with SASUnit: Best Practices

Getting Started with SASUnit: A Beginner’s Guide

What SASUnit is

SASUnit is an open-source unit testing framework for SAS programs that helps developers write, run, and organize automated tests to verify SAS code correctness and regression behavior.

Why use it

• Catch regressions early: Automated tests detect unintended changes.
• Improve code quality: Encourages modular, testable code.
• Streamline refactoring: Confidently change code with tests guarding behavior.
• Integrate with CI: Run SASUnit tests in continuous integration pipelines.

Key concepts

• Test case: A single test verifying one behavior (input → expected output).
• Test suite: A collection of related test cases.
• Fixtures: Setup/teardown steps for test environments (creating test tables, cleaning up).
• Assertions: Checks inside tests (e.g., equality of datasets, row counts, variable values).
• Test runner/report: Executes tests and produces pass/fail reports.

Basic setup (typical)

1. Install SASUnit files into a shared location accessible by your SAS environment.
2. Add SASUnit to your SASAUTOS/autoexec paths or include the main runner macro.
3. Create a test project folder with subfolders for test cases and fixtures.
4. Configure a test suite file that lists the test cases to run.
5. Run the test runner and review generated HTML/XML reports.

Writing your first test (example structure)

• Create a small SAS program or macro to test.
• Write a test case that:
  • Prepares input data (fixture).
  • Calls the program/macro.
  • Uses assertions to compare actual vs expected datasets or values.
  • Cleans up temporary data.

Common assertion types

• Dataset equality (all rows/columns match).
• Row/column counts.
• Value equality for specific variables.
• Existence/non-existence of datasets or variables.
• Macro return codes or log-check assertions.

Running tests and reading reports

• Run via the SASUnit runner macro or a command-line invocation (if configured).
• Reports typically include summary (passes/fails), detailed failures with diff-like info, and links to logs.

Integrating with CI

• Invoke SASJob via SAS command-line or batch mode inside CI jobs.
• Export reports in XML/HTML and fail CI on test failures.
• Store artifacts (reports/logs) for debugging.

Tips and best practices

• Start small: write tests for critical macros and ETL steps.
• Use fixtures to keep tests independent and repeatable.
• Keep datasets small and focused for faster tests.
• Write clear assertions and include expected-output artifacts.
• Run tests locally before adding to CI.

Resources to learn more

• Official SASUnit documentation and examples.
• Community blogs and examples of SASUnit test structures.
• Sample test repositories for pattern ideas.