mock-testing

name	mock-testing
description	Execute and debug Terraform mock tests for Azure CAF modules. Use this skill when user asks to test a module, run tests, or debug test failures.

Mock Testing for Azure CAF Modules

Mock tests validate that your Terraform module can successfully generate a plan without requiring actual Azure resources.

Terraform MCP Integration

When test failures indicate possible schema drift (missing/renamed attributes), confirm provider schema with:

• mcp_terraform_get_provider_details

When comparing expected module interfaces, use:

• mcp_terraform_search_modules
• mcp_terraform_get_module_details

Why Mock Testing is MANDATORY

Mock tests ensure:

• ✅ All variable references are correct
• ✅ Resource syntax is valid
• ✅ Dependencies are properly resolved
• ✅ No circular dependencies exist
• ✅ Examples work correctly
• ✅ No breaking changes introduced

Directory Structure: Examples and Mock Tests

Mock tests use the same configuration files as deployment examples:

examples/
├── <category>/
│   └── <service>/
│       └── 100-simple-service/
│           ├── configuration.tfvars     # Used for both deployment and mock tests
│           └── README.md
└── tests/
    └── mock/
        └── e2e_plan.tftest.hcl          # Test framework (validates syntax)

Configuration Pattern

Examples (examples/<category>/<service>/):

• Production-ready configuration patterns
• Key-based resource references for deployment
• Same files used for mock tests (validates syntax)
• Example: resource_group = { key = "rg1" }

Why This Works

Mock tests validate syntax without creating resources: The test framework uses mock providers to validate that Terraform can generate a valid plan without actually connecting to Azure.

Same configuration for both: Since mock tests only validate syntax and planning, the same key-based references work perfectly for both deployment and testing.

When to Run Mock Tests

MANDATORY scenarios:

1. After creating a new module - Before marking work complete
2. After updating a module - To catch regressions
3. Before committing changes - To validate all changes work together
4. After fixing variable references - To confirm corrections

⚠️ CRITICAL: Mock Tests vs Real Deployments

Mock tests validate syntax only - they don't deploy to Azure.

For real deployments, use terraform plan/apply in the examples directory:

# ✅ CORRECT - For real deployment
cd examples
terraform_with_var_files \
  --dir /chaos_studio/100-simple-chaos-target/ \
  --action plan

For mock tests, use terraform test command:

# ✅ CORRECT - For syntax validation (no Azure connection)
terraform -chdir=examples \
  test \
  -test-directory=./tests/mock \
  -var-file=./chaos_studio/100-simple-chaos-target/configuration.tfvars \
  -verbose

Mock examples contain fake Azure resource IDs that don't exist in your subscription.

How to Execute Mock Tests

Standard Mock Test Command:

cd examples
terraform test \
  -test-directory=./tests/mock \
  -var-file=./<category>/<service>/100-example/configuration.tfvars \
  -verbose

Example for chaos_studio module:

cd examples
terraform test \
  -test-directory=./tests/mock \
  -var-file=./chaos_studio/100-simple-chaos-target/configuration.tfvars \
  -verbose

Alternative (single command): Use terraform -chdir=examples test ... if you don't want to change directories.

⚠️ CRITICAL: Azure Subscription Verification (for real deployments only)

Mock tests do NOT require Azure subscription (they use mock providers).

For REAL deployments (terraform plan/apply), ALWAYS verify subscription first:

# 1. Check current Azure subscription
az account show --query "{subscriptionId:id, name:name, state:state}" -o table

# 2. Confirm with user this is correct
# MUST get explicit confirmation before plan/apply

# 3. Export for Terraform
export ARM_SUBSCRIPTION_ID=$(az account show --query id -o tsv)

Basic Test Execution

# Navigate to examples directory
cd /path/to/terraform-azurerm-caf/examples

# Initialize Terraform (required first time or after module changes)
terraform init -upgrade

# Run mock test for a specific example (NO subscription needed)
terraform test \
  -test-directory=./tests/mock \
  -var-file=./<category>/<service>/<example_number>/configuration.tfvars \
  -verbose

Example Commands

# Test chaos_studio module
cd examples
terraform init -upgrade
terraform test \
  -test-directory=./tests/mock \
  -var-file=./tests/chaos_studio/100-simple-chaos-target-mock/configuration.tfvars \
  -verbose

# Note: Use mock examples from tests/ directory, not deployment examples
# Mock examples have direct IDs, deployment examples have key-based references

# If testing deployment example (for actual deployment planning):
terraform test \
  -test-directory=./tests/mock \
  -var-file=./chaos_studio/100-simple-chaos-target/configuration.tfvars \
  -verbose

# Note: Deployment examples may fail in mock tests if they depend on
# remote_objects that aren't populated during mock testing

Expected Output

✅ Success

tests/mock/e2e_plan.tftest.hcl... in progress
  run "test_plan"... pass
tests/mock/e2e_plan.tftest.hcl... tearing down
tests/mock/e2e_plan.tftest.hcl... pass

Success! 1 passed, 0 failed.

❌ Failure

tests/mock/e2e_plan.tftest.hcl... in progress
  run "test_plan"... fail
╷
│ Error: Reference to undeclared input variable
│
│   on ../modules/category/service/variables.tf line 10:
│   10:   name = var.wrong_variable_name
│
│ An input variable with the name "wrong_variable_name" has not been declared.
╵

Common Mock Test Errors and Solutions

Error 1: Reference to Undeclared Input Variable

Error message:

Error: Reference to undeclared input variable
An input variable with the name "managed_redis" has not been declared.

Cause: Using resource-specific variable names instead of generic var.settings

Solution: Update all variable references to use var.settings

Example fix:

# ❌ WRONG
name = var.managed_redis.name

# ✅ CORRECT
name = var.settings.name

Files to check:

• modules/<category>/<module>/<module>.tf - Main resource file
• modules/<category>/<module>/locals.tf - Local variable definitions
• modules/<category>/<module>/diagnostics.tf - Diagnostics configuration

Error 2: Reference to Undeclared Local Value

Error message:

Error: Reference to undeclared local value
A local value with the name "tags" has not been declared.

Cause: Missing or incorrect local variable definitions

Solution: Ensure standard locals pattern is implemented in locals.tf:

locals {
  module_tag = {
    "category/module_name" = basename(abspath(path.module))
  }

  tags = merge(var.base_tags, local.module_tag, try(var.settings.tags, null))

  location = coalesce(
    try(var.settings.location, null),
    try(var.location, null),
    try(var.resource_group.location, null),
    try(var.resource_groups[try(var.settings.resource_group.lz_key, var.client_config.landingzone_key)][try(var.settings.resource_group.key, var.settings.resource_group_key)].location, null)
  )

  resource_group_name = coalesce(
    try(var.settings.resource_group_name, null),
    try(var.resource_group.name, null),
    try(var.resource_groups[try(var.settings.resource_group.lz_key, var.client_config.landingzone_key)][try(var.settings.resource_group.key, var.settings.resource_group_key)].name, null)
  )
}

Error 3: Invalid Reference in Dynamic Block

Error message:

Error: Invalid reference
A reference to a resource type must be followed by at least one attribute access

Cause: Using reserved keywords (e.g., module) as iterator names in dynamic blocks

Solution: Rename iterator to avoid reserved keywords

Example fix:

# ❌ WRONG - 'module' is a reserved keyword
dynamic "origins" {
  for_each = try(var.settings.origins, {})
  iterator = module
  
  content {
    name = module.value.name
  }
}

# ✅ CORRECT - Use descriptive name
dynamic "origins" {
  for_each = try(var.settings.origins, {})
  iterator = origin
  
  content {
    name = origin.value.name
  }
}

Error 4: Module Not Installed

Error message:

Error: Module not installed
This module is not yet installed. Run "terraform init" to install all modules required by this configuration.

Cause: Terraform not initialized or module changes not recognized

Solution:

cd examples
terraform init -upgrade

When to run:

• First time testing
• After creating new module
• After modifying module source paths
• After changing required_providers

Error 5: Invalid for_each Argument

Error message:

Error: Invalid for_each argument
The given "for_each" argument value is unsuitable

Cause: for_each receiving null or non-map/set value

Solution: Ensure proper default values with try()

Example fix:

# ❌ WRONG - Can receive null
for_each = var.settings.optional_blocks

# ✅ CORRECT - Defaults to empty map
for_each = try(var.settings.optional_blocks, {})

Error 6: Cycle Error (Circular Dependency)

Error message:

Error: Cycle: module.resource1, module.resource2

Cause: Circular dependency between modules

Solution:

1. Review dependency chain
2. Use explicit depends_on if needed
3. Restructure resource references
4. Check for mutual dependencies in remote_objects

Example fix:

# Add explicit dependency order
resource "azurerm_resource_a" "example" {
  # ...
  
  depends_on = [azurerm_resource_b.example]
}

Debugging Failed Tests

Step-by-Step Debugging Process

1. Read the full error message

   • Note the file and line number
   • Identify the variable or resource causing the issue

2. Check the module file

   # Open the file mentioned in error
   code modules/<category>/<module>/<file>.tf
   

3. Verify variable names

   • All references should use var.settings.*
   • NOT var.managed_redis.* or other resource-specific names

4. Check locals.tf exists and is complete

   • Must have: module_tag, tags, location, resource_group_name

5. Validate example configuration

   # Open the example tfvars
   code examples/<category>/<module>/100-*/configuration.tfvars
   

6. Check variable definitions

   # Verify variable is defined in module
   code modules/<category>/<module>/variables.tf
   

7. Re-run test after fix

   cd examples
   terraform test -test-directory=./tests/mock -var-file=./<path>/configuration.tfvars -verbose
   

Mock Test Workflow

┌─────────────────────────────────────┐
│  1. Make Changes to Module          │
└─────────────────┬───────────────────┘
                  │
                  ▼
┌─────────────────────────────────────┐
│  2. Navigate to examples/           │
│     cd examples                     │
└─────────────────┬───────────────────┘
                  │
                  ▼
┌─────────────────────────────────────┐
│  3. Initialize Terraform            │
│     terraform init -upgrade         │
└─────────────────┬───────────────────┘
                  │
                  ▼
┌─────────────────────────────────────┐
│  4. Run Mock Test                   │
│     terraform test ...              │
└─────────────────┬───────────────────┘
                  │
          ┌───────┴───────┐
          │               │
          ▼               ▼
    ┌─────────┐     ┌─────────┐
    │  PASS   │     │  FAIL   │
    └────┬────┘     └────┬────┘
         │               │
         │               ▼
         │     ┌──────────────────┐
         │     │  5. Debug Error  │
         │     │  - Read message  │
         │     │  - Check file    │
         │     │  - Fix issue     │
         │     └────┬─────────────┘
         │          │
         │          ▼
         │     ┌──────────────────┐
         │     │  6. Re-test      │
         │     └────┬─────────────┘
         │          │
         └──────────┴──────────────┐
                                   │
                                   ▼
                          ┌─────────────────┐
                          │  7. Commit      │
                          └─────────────────┘

Testing Multiple Examples

If a module has multiple examples, test each one:

cd examples

# Test all examples for a module
for config in ./<category>/<module>/*/configuration.tfvars; do
  echo "Testing: $config"
  terraform test -test-directory=./tests/mock -var-file="$config" -verbose
  if [ $? -ne 0 ]; then
    echo "FAILED: $config"
    break
  fi
done

Integration with CI/CD

Mock tests are also run in GitHub Actions workflows. Ensure your example is added to the appropriate workflow file:

• .github/workflows/standalone-scenarios.json
• .github/workflows/standalone-scenarios-additional.json
• .github/workflows/standalone-compute.json
• .github/workflows/standalone-networking.json
• .github/workflows/standalone-dataplat.json

Best Practices

1. Always test before committing - Catches issues early
2. Test after every change - Even small changes can break things
3. Fix root causes - Don't comment out failing code
4. Keep tests passing - Never commit code that breaks tests
5. Test all examples - If module has multiple examples, test each one
6. Document test commands - In module README.md for other developers

Quick Reference Commands

# Initialize
cd examples && terraform init -upgrade

# Test single example
terraform test -test-directory=./tests/mock -var-file=./path/to/configuration.tfvars -verbose

# Test with detailed output
TF_LOG=DEBUG terraform test -test-directory=./tests/mock -var-file=./path/to/configuration.tfvars -verbose

# Clean state between tests
rm -rf .terraform/ .terraform.lock.hcl
terraform init -upgrade

Checklist

Before marking testing complete:

• Navigated to examples/ directory
• Ran terraform init -upgrade
• Executed mock test for each example
• All tests pass successfully
• Fixed any errors found
• Verified no regression in existing examples
• Ready to commit changes

When Mock Tests Fail

DO:

• ✅ Read the full error message carefully
• ✅ Check the exact file and line number
• ✅ Verify variable naming (use var.settings)
• ✅ Ensure standard locals are complete
• ✅ Fix the root cause in the module
• ✅ Re-test after each fix

DON'T:

• ❌ Ignore test failures
• ❌ Comment out failing code
• ❌ Skip testing "small changes"
• ❌ Commit broken tests
• ❌ Assume tests will pass in CI if they fail locally