Testing catches problems before they reach production. Automated tests run on every change, providing immediate feedback.
Syntax validation. YAML, JSON, and template files parse correctly. No typos break deployment.
Linting. Configuration follows style guidelines. Consistent formatting across all files.
Unit tests. Individual functions work correctly. Template rendering produces expected output.
Integration tests. Changes work against real or simulated devices.
Tools: yamllint for YAML, ansible-lint for playbooks, pytest for Python, Batfish for network validation.