pytest-terraform 0.7.0
A pytest plugin for using terraform fixtures
License: Apache-2.0
Requires Python: <4.0,>=3.7

# Introduction

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pytest_terraform is a pytest plugin that enables executing terraform
to provision infrastructure in a unit/functional test as a fixture.

This plugin features uses a fixture factory pattern to enable paramterized
construction of fixtures via decorators.

## Usage

pytest_terraform provides a `terraform` decorator with the following parameters:

| Argument             | Required? | Type    | Default      | Description |
| -----                | :---:     | ---     | ---          | ---         |
| `terraform_dir`      | yes       | String  |              | Terraform module (directory) to execute. |
| `scope`              | no        | String  | `"function"` | [Pytest scope](https://docs.pytest.org/en/stable/fixture.html#scope-sharing-fixtures-across-classes-modules-packages-or-session) - should be one of: `function`, or `session`. Other scopes like  `class`, `module`, and `package` should work but have not been fully tested. |
| `replay`             | no        | Boolean | `True`       | Use recorded resources instead of invoking terraform. See [Replay Support](#replay-support) for more details. |
| `name`               | no        | String  | `None`       | Name used for the fixture. This defaults to the `terraform_dir` when `None` is supplied. |
| `teardown`           | no        | String  | `"default"`  | Configure which teardown mode is used for terraform resources. See [Teardown Options](#teardown-options) for more details. |

### Example

```python
from boto3 import Session
from pytest_terraform import terraform


# We use the terraform decorator to create a fixture with the name of
# the terraform module.
#
# The test function will be invoked after the terraform module is provisioned
# with the results of the provisioning.
#
# The module `aws_sqs` will be searched for in several directories, the test
# file directory, a sub directory `terraform`.
#
# This fixture specifies a session scope and will be run once per test run.
#
@terraform('aws_sqs', scope='session')
def test_sqs(aws_sqs):
    # A test is passed a terraform resources class containing content from
    # the terraform state file.
    #
    # Note the state file contents may vary across terraform versions.
    #
    # We can access nested datastructures with a jmespath expression.
    assert aws_sqs["aws_sqs_queue.test_queue.tags"] == {
        "Environment": "production"
    }
   queue_url = aws_sqs['test_queue.queue_url']
   print(queue_url)


def test_sqs_deliver(aws_sqs):
   # Once a fixture has been defined with a decorator
   # it can be reused in the same module by name, with provisioning
   # respecting scopes.
   #
   sqs = Session().client('sqs')
   sqs.send_message(
       QueueUrl=aws_sqs['test_queue.queue_url'],
       MessageBody=b"123")


@terraform('aws_sqs')
def test_sqs_dlq(aws_sqs):
   # the fixture can also referenced again via decorator, if redefined
   # with decorator the fixture parameters much match (ie same session scope).

   # Module outputs are available as a separate mapping.
   aws_sqs.outputs['QueueUrl']
```

*Note* the fixture name should match the terraform module name

*Note* The terraform state file is considered an internal
implementation detail of terraform, not per se a stable public interface
across versions.

## Marks

All tests using terraform fixtures have a `terraform` mark applied so
they can be run/selected via the command line ie.

```shell
pytest -k terraform tests/
```

to run all terraform tests only. See pytest mark documentation for
additional details, https://docs.pytest.org/en/stable/example/markers.html#mark-examples


## Options

You can provide the path to the terraform binary else its auto discovered
```shell
--tf-binary=$HOME/bin/terraform
```

Terraform modules referenced by fixtures are looked up in a few different
locations, directly in the same directory as the test module, in a subdir
named terraform, and in a sibling directory named terraform. An explicit
directory can be given which will be looked at first for all modules.

```shell
--tf-mod-dir=terraform
```

This plugin also supports flight recording (see next section)
```shell
--tf-replay=[record|replay|disable]
```

### Teardown Options

`pytest_terraform` supports three different teardown modes for the terraform decorator.
The default, `pytest_terraform.teardown.ON` will always attempt to teardown any and all modules via `terraform destory`.
If for any reason destroy fails it will raise an exception to alert the test runner.
The next mode, `pytest_terraform.teardown.IGNORE`, will invoke `terraform destroy` as with `teardown.ON` but will ignore any failures.
This mode is particularly help if your test function performs destructive actions against any objects created by the terraform module.
The final option is `pytest_terraform.teardown.OFF` which will remove the teardown method register all together.
This should generally only be used in very specific situations and is considered an edge case.

There is a special `pytest_terraform.teardown.DEFAULT` which is what the `teardown` parameter actually defaults to.

Teardown options are available, for convenience, on the terraform decorator.
For example, set teardown to ignore:

```python
from pytest_terraform import terraform


@terraform('aws_sqs', teardown=terraform.TEARDOWN_IGNORE)
def test_sqs(aws_sqs):
    assert aws_sqs["aws_sqs_queue.test_queue.tags"] == {
        "Environment": "production"
    }
   queue_url = aws_sqs['test_queue.queue_url']
   print(queue_url)
```

## Hooks

pytest_terraform provides hooks via the pytest hook implementation.
Hooks should be added in the `conftest.py` file.

### `pytest_terraform_modify_state`

This hook is executed after state has been captured from terraform apply and before writing to disk.
This hook does not modify state that's passed to the function under test.
The state is passed as the kwarg `tfstate` which is a `TerraformStateJson` UserString class with the following methods and properties:

- `TerraformStateJson.dict` - The deserialized state as a dict
- `TerraformStateJson.update(state: str)` - Replace the serialized state with a new state string
- `TerraformStateJson.update_dict(state: dict)` - Replace the serialized state from a dictionary

#### Example

```python
def pytest_terraform_modify_state(tfstate):
    print(str(tfstate))
```

#### Example AWS Account scrub

```python
import re

def pytest_terraform_modify_state(tfstate):
    """ Replace potential AWS account numbers with 'REDACTED' """
    tfstate.update(re.sub(r'([0-9]+){12}', 'REDACTED', str(tfstate)))
```

## Flight Recording

The usage/philosophy of this plugin is based on using flight recording
for unit tests against cloud infrastructure. In flight recording rather
than mocking or stubbing infrastructure, actual resources are created
and interacted with with responses recorded, with those responses
subsequently replayed for fast test execution. Beyond the fidelity
offered, this also enables these tests to be executed/re-recorded against
live infrastructure for additional functional/release testing.

https://cloudcustodian.io/docs/developer/tests.html#creating-cloud-resources-with-terraform

### Replay Support

By default fixtures will save a `tf_resources.json` back to the module
directory, that will be used when in replay mode.

Replay can be configured by passing --tf-replay on the cli or via pytest config file.

### Recording

Passing the fixture parameter `replay` can control the replay behavior on an individual
test. The default is to operate in recording mode.

@terraform('file_example', replay=False)
def test_file_example(file_example):
    assert file_example['local_file.bar.content'] == 'bar!'


## XDist Compatibility

pytest_terraform supports pytest-xdist in multi-process (not distributed)
mode.

When run with python-xdist, pytest_terraform treats all non functional
scopes as per test run fixtures across all workers, honoring their
original scope lifecycle but with global semantics, instead of once
per worker (xdist default).

To enable this the plugin does multi-process coodination using lock
files, a test execution log, and a dependency mapping of fixtures
to tests. Any worker can execute a module teardown when its done executing
the last test that depends on a given fixture. All provisioning and
teardown are guarded by atomic file locks in the pytest execution's temp
directory.

### Root module references

`terraform_remote_state` can be used to introduce a dependency between
a scoped root modules on an individual test, note we are not
attempting to support same scope inter fixture dependencies as that
imposes additional scheduling constraints outside of pytest native
capabilities. The higher scoped root module (ie session or module scoped)
will need to have output variables to enable this consumption.