terraform-test

To write Terraform tests, you create `.tftest.hcl` or `.tftest.json` files containing run blocks that execute `apply` or `plan` commands, along with assertions to validate your infrastructure state and outputs.

Mock providers in Terraform testing simulate provider behavior to enable isolated testing of configurations. You use them when you need to validate module logic without deploying real cloud resources or relying on external API endpoints.

You validate Terraform module outputs by defining assertions within your test run blocks. These assertions check the infrastructure state and output values returned by `apply` or `plan` commands to ensure they match expected configurations.

Yes, you can test Terraform modules without real deployments by using mock providers to simulate infrastructure behavior. This allows you to run isolated unit tests validating configuration logic before executing integration tests.

In `.tftest.hcl` files, `plan` run blocks execute a Terraform plan to validate expected changes without modifying state, while `apply` run blocks execute the configuration to provision resources and test the actual resulting infrastructure state.

Terraform tests may fail during CI/CD execution due to misconfigured mock providers, incorrect assertion logic against outputs, or invalid run block structures in your `.tftest.hcl` files. Troubleshoot by validating test file syntax and module configurations.