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Testing in Terraform

Testing in Terraform is essential for ensuring the reliability and robustness of Infrastructure as Code (IaC) configurations. There are various testing strategies and tools available for Terraform, ranging from unit tests to end-to-end tests.

Testing Strategies

1. Unit Tests: These tests are simple and basic, typically involving checking the output of a Terraform command or validating the generated Terraform plan.
2. Integration Tests: These tests involve running the actual Terraform commands and validating the results.
3. Contract Tests: These tests use pre-conditions, post-conditions, and validations for variables and resources to ensure that the system behaves as expected.
4. End-to-End Tests: These tests use tools like terratest and kitchen-terraform to simulate the entire deployment process and validate the final state of the infrastructure.

Tools

1. Terraform Built-in Commands: Terraform provides built-in commands like terraform validate and terraform plan for validation and planning, respectively.
2. Terratest: A popular tool for testing Terraform configurations, providing a comprehensive suite of testing tools and plugins.
3. Kitchen-Terraform: An open-source set of Test Kitchen plugins for testing Terraform configuration, allowing you to create and manage test environments locally.
4. IaC-TLD-DevOps: A GitHub repository that demonstrates the use of Test-Later Development (TLD) method for building IaC, including a presentation and a quickstart guide.

Testing Process

The testing process in Terraform typically involves the following steps:

1. Writing tests, which can be done using TDD or TLD methods.
2. Running tests, which can involve unit tests, integration tests, contract tests, and end-to-end tests.
3. Adjusting the code based on the test results, which may involve refactoring or implementing additional features.

Sources: Terratest Kitechen terraform IaC TLD DevOps