Lists multiple specific concrete actions and artifacts: 'test files, run blocks, assertions, mock providers, plan-mode unit tests, apply-mode integration tests, test troubleshooting.' These are precise, actionable capabilities.

Clearly answers both 'what' (write and run Terraform tests with specific capabilities listed under USE FOR) and 'when' (explicit WHEN clause with trigger terms). Also includes a DO NOT USE FOR clause to further clarify boundaries.

Excellent coverage of natural terms users would say: 'create test', 'write test', 'terraform test', '.tftest.hcl', 'mock provider', 'test module', 'validate infrastructure', 'test assertion'. These match how users naturally phrase requests.

Highly distinctive with clear niche: Terraform test files specifically (.tftest.hcl). The DO NOT USE FOR clause explicitly excludes Bicep, architecture decisions, and deployment, reducing conflict risk with related infrastructure skills.

The content is lean and efficient. It uses tables for quick reference, avoids explaining basic Terraform concepts, and delegates detailed examples to reference files. Every section earns its place without unnecessary padding.

The skill provides concrete CLI commands and assert syntax, but the canonical example is deferred to a reference file rather than shown inline. The main file lacks a complete, copy-paste-ready test file example, which would significantly improve actionability.

The file structure and running tests sections provide some workflow guidance, but there's no explicit step-by-step workflow for creating a test (e.g., create file → write run blocks → validate → run → interpret results). There are no validation checkpoints or error recovery feedback loops for the test-writing process.

Excellent progressive disclosure with a clear overview in the main file and well-signaled, one-level-deep references to four specific reference files. The reference index table at the bottom provides easy navigation, and content is appropriately split between overview and detailed materials.