Terraform Test

This is the Terraform test framework reference you'll actually use when writing `.tftest.hcl` files. It covers the full structure: run blocks with plan vs apply modes, assertions on outputs and resource attributes, sequential tests that chain state, and parallel execution patterns. The mock provider section only applies to Terraform 1.7.0+, so it'll tell you to skip that if you're on an older version. What I like here is the naming convention guidance (use `*_unit_test.tftest.hcl` for plan mode, `*_integration_test.tftest.hcl` for apply mode) since that makes CI filtering dead simple. Also includes CI/CD pipeline examples and a complete VPC module test suite in the references.