Introduction to Terraform test command

How to test in terraform

Test is a new feature in 0.15 version (Still experimental)

It allows you to perform integration test without a third-party like Terratest.
The Test will deploy the infrastructure on an AWS account (You need to setup credentials). It will perform plan, apply, perform tests with the collected data, destroy

File structure

In your repository create a test or tests folder.
Inside this folder you can create one or more folders that will contains your tests cases.

├──tests
│  ├──test_case_1
│  │  └──test_case_1.tf
│  └──test_case_2
│     └──test_case_2.tf
├──.gitignore
├──.terraform.lock.hcl
├──LICENSE
├──README.md
├──backend.tf
├──provider.tf
└──version.tf

Only the file .tf must start with test_.
It does not matter if the folder's name contains test

Test_file.tf

The test files must use a specific provider plus the provider you want to use in your terraform stack.

terraform {
  required_providers {
    test = {
      source = "terraform.io/builtin/test"
    }
  }
}

Import your module inside your test case with the standard hcl block

module "main" {
  source = "PATH_TO_YOUR_MODULE"
}

In the test file, the principal resource to use is test_assertion:

resource "test_assertions" "my_asssertion" {}

This resource must contain the component parameter.
component is an unique identifier for the assertion resource in the test results.

Output value to point to the failed test will be displayed with the format folder_name.component.[equal or check block]_name

Example:

bucket.bucket_region_from_aws.region

Block equal or check are used inside to define the tests

equal "my_equal" {
    description = ""
    got         = The value deployed
    want        = The correct value i need
  }

  check "my_check" {
    description = ""
    condition   = Use a fonction that return true or false like can() 
  }

With these block you can check the module's outputs.
You can also check the value of a deployed resource by fetching the information with a data_source block.

Example of test outputs:

Failed:

Check Test:

─── Failed: test_case_folder.component.test_name (Test description) ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
condition failed

Equal Test:

─── Failed: test_case_folder.component.test_name (Test description) ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
wrong value
    got:  "value1"
    want: "value2"

Success:

Success! All of the test assertions passed.