Fixes terraform-google-modules#12: Add testing based on new approach

terraform-google-modules#12

Updated testing.

CONTRIBUTING.md

@@ -0,0 +1,104 @@
+# Contributing
+
+This document provides guidelines for contributing to the module VPC service controls.
+
+## Dependencies
+
+The following dependencies must be installed on the development system:
+
+- [Docker Engine][docker-engine]
+- [Google Cloud SDK][google-cloud-sdk]
+- [make]
+
+## Generating Documentation for Inputs and Outputs
+
+The Inputs and Outputs tables in the READMEs of the root module,
+submodules, and example modules are automatically generated based on
+the `variables` and `outputs` of the respective modules. These tables
+must be refreshed if the module interfaces are changed.
+
+### Execution
+
+Run `make generate_docs` to generate new Inputs and Outputs tables.
+
+## Integration Testing
+
+Integration tests are used to verify the behaviour of the root module,
+submodules, and example modules. Additions, changes, and fixes should
+be accompanied with tests.
+
+The integration tests are run using [Kitchen][kitchen],
+[Kitchen-Terraform][kitchen-terraform], and [InSpec][inspec]. These
+tools are packaged within a Docker image for convenience.
+
+The general strategy for these tests is to verify the behaviour of the
+[example modules](./examples/), thus ensuring that the root module,
+submodules, and example modules are all functionally correct.
+
+### Test Environment
+The easiest way to test the module is in an isolated test project. The setup for such a project is defined in [test/setup](./test/setup/) directory.
+
+To use this setup, you need a service account with Project Creator access on a folder. Export the Service Account credentials to your environment like so:
+
+```
+export SERVICE_ACCOUNT_JSON=$(< credentials.json)
+```
+
+You will also need to set a few environment variables:
+```
+export TF_VAR_org_id="your_org_id"
+export TF_VAR_folder_id="your_folder_id"
+export TF_VAR_billing_account="your_billing_account_id"
+```
+
+With these settings in place, you can prepare a test project using Docker:
+```
+make docker_test_prepare
+```
+
+To remove Access Policy, if any exists, run funcion inside Docker:
+```
+remove_gcloud_org_accesspolicy
+```
+
+### Noninteractive Execution
+
+Run `make docker_test_integration` to test all of the example modules
+noninteractively, using the prepared test project.
+
+### Interactive Execution
+
+1. Run `make docker_run` to start the testing Docker container in
+   interactive mode.
+
+1. Run `kitchen_do create <EXAMPLE_NAME>` to initialize the working
+   directory for an example module.
+
+1. Run `kitchen_do converge <EXAMPLE_NAME>` to apply the example module.
+
+1. Run `activate_gcloud_sa && kitchen_do verify <EXAMPLE_NAME>` to test the example module.
+
+1. Run `kitchen_do destroy <EXAMPLE_NAME>` to destroy the example module
+   state.
+
+## Linting and Formatting
+
+Many of the files in the repository can be linted or formatted to
+maintain a standard of quality.
+
+### Execution
+
+Run `make docker_test_lint`.
+
+[docker-engine]: https://www.docker.com/products/docker-engine
+[flake8]: http://flake8.pycqa.org/en/latest/
+[gofmt]: https://golang.org/cmd/gofmt/
+[google-cloud-sdk]: https://cloud.google.com/sdk/install
+[hadolint]: https://github.com/hadolint/hadolint
+[inspec]: https://inspec.io/
+[kitchen-terraform]: https://github.com/newcontext-oss/kitchen-terraform
+[kitchen]: https://kitchen.ci/
+[make]: https://en.wikipedia.org/wiki/Make_(software)
+[shellcheck]: https://www.shellcheck.net/
+[terraform-docs]: https://github.com/segmentio/terraform-docs
+[terraform]: https://terraform.io/