This simple helper facilitates testing Terraform modules from Python unit tests, by wrapping the Terraform executable and exposing convenience methods to set up fixtures, execute Terraform commands, and parse their output.
It allows for different types of tests: lightweight tests that only use Terraform init and plan to ensure code is syntactically correct and the right number and type of resources should be created, or full-fledged tests that run the full apply/output/destroy cycle, and can then be used to test the actual created resources, or the state file.
As an additional convenience, the module also provides an easy way to request and access the plan output (via terraform plan -out and terraform show) and the outputs (via terraform output -json), and return them wrapped in simple classes that streamline accessing their attributes.
This module is heavily inspired by two projects: Terratest for the lightweight approach to testing Terraform, and python-terraform for wrapping the Terraform command in Python.
The test folder contains simple examples on how to write tests for both plan and apply, using either synthetic fixtures (simple representations of the plan output and output files), or minimal root modules. More examples can be found in the Cloud Foundation Fabric repository, for which this module was developed.
This is a test that uses plan output on an actual module:
import pytest
import tftest
@pytest.fixture
def plan(fixtures_dir):tf=tftest.TerraformTest('plan', fixtures_dir)
tf.setup(extra_files=['plan.auto.tfvars'])
return tf.plan(output=True)
def test_variables(plan):
assert 'prefix' in plan.variables
assert plan.variables['names'] == ['one', 'two']
def test_outputs(plan):
assert sorted(plan.outputs['gcs_buckets'].keys()) == plan.variables['names']
def test_root_resource(plan):res=plan.resources['google_project_iam_member.test_root_resource']
assert res['values']['project'] == plan.variables['project_id']
def test_modules(plan):mod=plan.modules['module.gcs-buckets']
res=mod.resources['google_storage_bucket.buckets[0]']
assert res['values']['location'] == plan.variables['gcs_location']Support for Terragrunt actually follows the same principle of the thin TerraformTest wrapper.
Please see the following example for how to use it:
importpytestimporttftest@pytest.fixturedefrun_all_apply_out(fixtures_dir):
# notice for run-all, you need to specify when TerragruntTest is constructedtg=tftest.TerragruntTest('tg_apply_all', fixtures_dir, tg_run_all=True)
# the rest is very similar to how you use TerraformTesttg.setup()
# to use --terragrunt-<option>, pass in tg_<option in snake case>tg.apply(output=False, tg_non_interactive=True)
yieldtg.output()
tg.destroy(auto_approve=True, tg_non_interactive=True)
deftest_run_all_apply(run_all_apply_out):
triggers= [o["triggers"] foroinrun_all_apply_out]
assert [{'name': 'foo', 'template': 'sample template foo'}] intriggersassert [{'name': 'bar', 'template': 'sample template bar'}] intriggersassert [{'name': 'one', 'template': 'sample template one'},
{'name': 'two', 'template': 'sample template two'}] intriggersassertlen(run_all_apply_out) ==3Starting from version 1.0.0 Terraform 0.12 is required, and tests written with previous versions of this module are incompatible. Check the CHANGELOG.md file for details on what's changed.
Tests use the pytest framework and have no other dependency except on the Terraform binary. The version used during development is in the DEV-REQUIREMENTS.txt file.
This is not an officially supported Google product.