moto/CONTRIBUTING.md

# Contributing code

Moto has a [Code of Conduct](https://github.com/spulec/moto/blob/master/CODE_OF_CONDUCT.md), you can expect to be treated with respect at all times when interacting with this project.

## Running the tests locally

Moto has a [Makefile](./Makefile) which has some helpful commands for getting set up.
You should be able to run `make init` to install the dependencies and then `make test` to run the tests.

*NB. On first run, some tests might take a while to execute, especially the Lambda ones, because they may need to download a Docker image before they can execute.*

## Linting

Run `make lint` or `black --check moto tests` to verify whether your code confirms to the guidelines.

## Getting to grips with the codebase

Moto maintains a list of [good first issues](https://github.com/spulec/moto/contribute) which you may want to look at before
implementing a whole new endpoint.

## Missing features

Moto is easier to contribute to than you probably think. There's [a list of which endpoints have been implemented](https://github.com/spulec/moto/blob/master/IMPLEMENTATION_COVERAGE.md) and we invite you to add new endpoints to existing services or to add new services.

How to teach Moto to support a new AWS endpoint:

* Search for an existing [issue](https://github.com/spulec/moto/issues) that matches what you want to achieve.
* If one doesn't already exist, create a new issue describing what's missing. This is where we'll all talk about the new addition and help you get it done.
* Create a [pull request](https://help.github.com/articles/using-pull-requests/) and mention the issue # in the PR description.
* Try to add a failing test case. For example, if you're trying to implement `boto3.client('acm').import_certificate()` you'll want to add a new method called `def test_import_certificate` to `tests/test_acm/test_acm.py`.
* Implementing the feature itself can be done by creating a method called `import_certificate` in `moto/acm/responses.py`. It's considered good practice to deal with input/output formatting and validation in `responses.py`, and create a method `import_certificate` in `moto/acm/models.py` that handles the actual import logic.
* If you can also implement the code that gets that test passing then great! If not, just ask the community for a hand and somebody will assist you.

## Before pushing changes to GitHub

1. Run `black moto/ tests/` over your code to ensure that it is properly formatted
1. Run `make test` to ensure your tests are passing

## Python versions

moto currently supports both Python 2 and 3, so make sure your tests pass against both major versions of Python.

## Missing services

Implementing a new service from scratch is more work, but still quite straightforward. All the code that intercepts network requests to `*.amazonaws.com` is already handled for you in `moto/core` - all that's necessary for new services to be recognized is to create a new decorator and determine which URLs should be intercepted.

See this PR for an example of what's involved in creating a new service: https://github.com/spulec/moto/pull/2409/files

Note the `urls.py` that redirects all incoming URL requests to a generic `dispatch` method, which in turn will call the appropriate method in `responses.py`. 

If you want more control over incoming requests or their bodies, it is possible to redirect specific requests to a custom method. See this PR for an example: https://github.com/spulec/moto/pull/2957/files

### Generating template code of services.

By using `scripts/scaffold.py`, you can automatically generate template code of new services and new method of existing service. The script looks up API specification of given boto3 method and adds necessary codes includng request parameters and response parameters. In some cases, it fails to generate codes.
Please try out by runninig `python scripts/scaffold.py`

```bash
$ python scripts/scaffold.py
Select service: codedeploy

==Current Implementation Status==
[ ] add_tags_to_on_premises_instances
...
[ ] create_deployment
...[
[ ] update_deployment_group
=================================
Select Operation: create_deployment


	Initializing service	codedeploy
	creating	moto/codedeploy
	creating	moto/codedeploy/models.py
	creating	moto/codedeploy/exceptions.py
	creating	moto/codedeploy/__init__.py
	creating	moto/codedeploy/responses.py
	creating	moto/codedeploy/urls.py
	creating	tests/test_codedeploy
	creating	tests/test_codedeploy/test_server.py
	creating	tests/test_codedeploy/test_codedeploy.py
	inserting code	moto/codedeploy/responses.py
	inserting code	moto/codedeploy/models.py
You will still need to add the mock into "__init__.py"
```


## Maintainers

### Releasing a new version of Moto

You'll need a PyPi account and a DockerHub account to release Moto. After we release a new PyPi package we build and push the [motoserver/moto](https://hub.docker.com/r/motoserver/moto/) Docker image.

* First, `scripts/bump_version` modifies the version and opens a PR
* Then, merge the new pull request
* Finally, generate and ship the new artifacts with `make publish`