Test file structure in Terraform - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of a test file in Terraform?

A test file in Terraform is used to check if your infrastructure code works as expected before applying changes. It helps catch errors early.

beginner

Where should Terraform test files be placed in your project?

Terraform test files are usually placed in a separate folder named tests or alongside your modules with a _test.tf suffix to keep tests organized and easy to find.

beginner

What naming convention is commonly used for Terraform test files?

Test files often use the suffix _test.tf to clearly indicate they contain tests, making it easy to separate them from main configuration files.

intermediate

Why is it important to keep test files separate from production Terraform files?

Keeping test files separate prevents accidental deployment of test resources and helps maintain a clean, understandable project structure.

intermediate

What tools can be used to run tests on Terraform configurations?

Tools like terraform validate, terraform plan, and third-party tools like terratest help automate testing of Terraform code.

Where is the best place to put Terraform test files?

A In the root directory only

B Mixed with production files without distinction

C Inside the <code>.terraform</code> hidden folder

D In a separate <code>tests</code> folder or with a <code>_test.tf</code> suffix

Test files should be organized separately or clearly named to avoid confusion and accidental deployment.

What suffix is commonly used for Terraform test files?

A _test.tf

B _prod.tf

C _config.tf

D _deploy.tf

The _test.tf suffix clearly marks files as tests.

Which command helps check Terraform code syntax before deployment?

A terraform apply

B terraform destroy

C terraform validate

D terraform output

terraform validate checks the syntax and configuration correctness.

Why keep test files separate from production files?

A To prevent accidental deployment of test resources

B To hide test files from version control

C To reduce file size

D To speed up deployment

Separating test files avoids deploying test resources by mistake.

Which tool is NOT typically used for testing Terraform code?

A terraform plan

B docker-compose

C terraform validate

D terratest

docker-compose is unrelated to Terraform testing.

Explain how you would organize test files in a Terraform project and why.

Think about how to keep test code apart from production code.

Describe the role of terraform validate in testing Terraform configurations.

It is a command to check your code before applying.

Practice

1. What is the main reason to keep Terraform test files separate from production code files?

easy

A. Because Terraform does not support test files inside the main folder

B. To avoid mixing test code with production code and keep the project organized

C. To reduce the size of the Terraform state file

D. Because test files must be written in a different language

Solution

1. Step 1: Understand file organization purpose

   Separating test files helps keep the project clean and easier to manage by not mixing test and production code.

2. Step 2: Recognize Terraform best practices

   Terraform encourages clear separation to avoid confusion and accidental deployment of test code.

3. Final Answer:

   To avoid mixing test code with production code and keep the project organized -> Option B

4. Quick Check:

   Separate test files = organized project [OK]

Hint: Keep test files separate to avoid confusion [OK]

Common Mistakes:

• Thinking test files must be in main folder
• Believing test files affect state size
• Assuming test files require different language

2. Which of the following is the correct folder structure for organizing Terraform files including tests?

easy

A. /main.tf, /variables.tf, /outputs.tf, /test/main_test.tf

B. /main.tf, /variables.tf, /outputs.tf, /modules/tests/test_main.tf

C. /main.tf, /variables.tf, /outputs.tf, /tests/test_main.tf

D. /main.tf, /variables.tf, /outputs.tf, /tests/main_test.tf

Solution

1. Step 1: Identify standard test folder naming

   Tests are usually placed in a separate folder named 'tests' at the root level for clarity.

2. Step 2: Check file naming conventions

   Test files often have '_test' suffix to indicate their purpose, e.g., 'main_test.tf'.

3. Final Answer:

   /main.tf, /variables.tf, /outputs.tf, /tests/main_test.tf -> Option D

4. Quick Check:

   Tests folder with *_test.tf files = correct structure [OK]

Hint: Use 'tests' folder with *_test.tf files [OK]

Common Mistakes:

• Placing tests inside modules folder
• Naming test folder as 'test' instead of 'tests'
• Not using _test suffix for test files

3. Given this Terraform project structure:

/main.tf
/variables.tf
/outputs.tf
/tests/test_main.tf

What will happen if you run terraform apply from the root directory?

medium

A. Terraform will apply infrastructure defined in main.tf and ignore test files

B. Terraform will apply both main.tf and test_main.tf causing errors

C. Terraform will only apply test_main.tf and ignore main.tf

D. Terraform will fail because test files are not allowed

Solution

1. Step 1: Understand Terraform file loading behavior

   Terraform loads *.tf files in the current directory but ignores files in subfolders unless explicitly included.

2. Step 2: Recognize test folder separation effect

   Files inside /tests are not loaded by default during terraform apply, so only main.tf and related files are applied.

3. Final Answer:

   Terraform will apply infrastructure defined in main.tf and ignore test files -> Option A

4. Quick Check:

   Terraform applies root *.tf files only [OK]

Hint: Terraform ignores test folder files by default [OK]

Common Mistakes:

• Assuming terraform applies all .tf files recursively
• Thinking test files run automatically
• Believing terraform apply fails due to test files

4. You have this folder structure:

/main.tf
/variables.tf
/outputs.tf
/tests/test_main.tf

Running terraform apply gives an error about duplicate resource definitions. What is the likely cause?

medium

A. Outputs are missing in outputs.tf

B. Variables are defined twice in variables.tf

C. Terraform is loading test_main.tf and main.tf causing duplicate resources

D. Terraform state file is corrupted

Solution

1. Step 1: Analyze error cause

   Duplicate resource errors usually mean Terraform sees the same resource defined more than once.

2. Step 2: Check file loading

   If test files are accidentally loaded (e.g., by running terraform in /tests), resources duplicate with main.tf definitions.

3. Final Answer:

   Terraform is loading test_main.tf and main.tf causing duplicate resources -> Option C

4. Quick Check:

   Duplicate resources = multiple files loaded [OK]

Hint: Run terraform only in root, not in tests folder [OK]

Common Mistakes:

• Blaming variables or outputs for duplicate resource error
• Ignoring that test files can cause duplicates if loaded
• Assuming state file corruption without checking files

5. You want to reuse infrastructure code in multiple projects and keep tests separate. Which folder structure best supports this using Terraform modules and tests?

hard

A. /modules/network/main.tf, /modules/network/variables.tf, /tests/network_test.tf, /main.tf

B. /network/main.tf, /network/variables.tf, /tests/network_test.tf, /main.tf

C. /modules/network/main.tf, /tests/network/main_test.tf, /main.tf

D. /modules/network/main.tf, /modules/network/tests/network_test.tf, /main.tf

Solution

1. Step 1: Identify module folder best practice

   Modules should be inside a 'modules' folder with their own files for reuse.

2. Step 2: Separate tests outside modules

   Tests should be in a top-level 'tests' folder to avoid mixing with reusable module code.

3. Final Answer:

   /modules/network/main.tf, /modules/network/variables.tf, /tests/network_test.tf, /main.tf -> Option A

4. Quick Check:

   Modules in 'modules', tests in 'tests' folder [OK]

Hint: Keep modules and tests in separate top-level folders [OK]

Common Mistakes:

• Placing tests inside modules folder
• Not using a modules folder for reusable code
• Mixing test files with main project files