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https://github.com/exoego/rspec-openapi

Generate OpenAPI schema from RSpec request specs
https://github.com/exoego/rspec-openapi

openapi rails rspec ruby

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Generate OpenAPI schema from RSpec request specs

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# rspec-openapi [![Gem Version](https://badge.fury.io/rb/rspec-openapi.svg)](https://rubygems.org/gems/rspec-openapi) [![test](https://github.com/exoego/rspec-openapi/actions/workflows/test.yml/badge.svg)](https://github.com/exoego/rspec-openapi/actions/workflows/test.yml) [![codecov](https://codecov.io/gh/exoego/rspec-openapi/branch/master/graph/badge.svg?token=egYm6AlxkD)](https://codecov.io/gh/exoego/rspec-openapi) [![Ruby-toolbox](https://img.shields.io/badge/ruby-toolbox-a61414?cacheSeconds=31536000)](https://www.ruby-toolbox.com/projects/rspec-openapi)

Generate OpenAPI schema from RSpec request specs.

## What's this?

There are some gems which generate OpenAPI specs from RSpec request specs.
However, they require a special DSL specific to these gems, and we can't reuse existing request specs as they are.

Unlike such [existing gems](#links), rspec-openapi can generate OpenAPI specs from request specs without requiring any special DSL.
Furthermore, rspec-openapi keeps manual modifications when it merges automated changes to OpenAPI specs
in case we can't generate everything from request specs.

## Installation

Add this line to your application's Gemfile:

```ruby
gem 'rspec-openapi', group: :test
```

## Usage

Run rspec with OPENAPI=1 to generate `doc/openapi.yaml` for your request specs.

```bash
$ OPENAPI=1 bundle exec rspec
```

### Example

Let's say you have [a request spec](https://github.com/exoego/rspec-openapi/blob/24e5c567c2e90945c7a41f19f71634ac028cc314/spec/requests/rails_spec.rb#L38) like this:

```rb
RSpec.describe 'Tables', type: :request do
describe '#index' do
it 'returns a list of tables' do
get '/tables', params: { page: '1', per: '10' }, headers: { authorization: 'k0kubun' }
expect(response.status).to eq(200)
end

it 'does not return tables if unauthorized' do
get '/tables'
expect(response.status).to eq(401)
end
end

# ...
end
```

If you run the spec with `OPENAPI=1`,

```
OPENAPI=1 rspec spec/requests/tables_spec.rb
```

It will generate [`doc/openapi.yaml` file](./spec/rails/doc/openapi.yaml) like:

```yml
openapi: 3.0.3
info:
title: rspec-openapi
paths:
"/tables":
get:
summary: index
tags:
- Table
parameters:
- name: page
in: query
schema:
type: integer
example: 1
- name: per
in: query
schema:
type: integer
example: 10
responses:
'200':
description: returns a list of tables
content:
application/json:
schema:
type: array
items:
type: object
properties:
id:
type: integer
name:
type: string
# ...
```

and the schema file can be used as an input of [Swagger UI](https://github.com/swagger-api/swagger-ui) or [Redoc](https://github.com/Redocly/redoc).

![Redoc example](./spec/apps/rails/doc/screenshot.png)

### Configuration

The following configurations are optional.

```rb
require 'rspec/openapi'

# Change the path to generate schema from `doc/openapi.yaml`
RSpec::OpenAPI.path = 'doc/schema.yaml'

# Change the output type to JSON
RSpec::OpenAPI.path = 'doc/schema.json'

# Or generate multiple partial schema files, given an RSpec example
RSpec::OpenAPI.path = -> (example) {
case example.file_path
when %r[spec/requests/api/v1/] then 'doc/openapi/v1.yaml'
when %r[spec/requests/api/v2/] then 'doc/openapi/v2.yaml'
else 'doc/openapi.yaml'
end
}

RSpec::OpenAPI.title = 'OpenAPI Documentation'

# Disable generating `example`
RSpec::OpenAPI.enable_example = false

# Change `info.version`
RSpec::OpenAPI.application_version = '1.0.0'

# Set the info header details
RSpec::OpenAPI.info = {
description: 'My beautiful API',
license: {
'name': 'Apache 2.0',
'url': 'https://www.apache.org/licenses/LICENSE-2.0.html'
}
}

# Set request `headers` - generate parameters with headers for a request
RSpec::OpenAPI.request_headers = %w[X-Authorization-Token]

# Set response `headers` - generate parameters with headers for a response
RSpec::OpenAPI.response_headers = %w[X-Cursor]

# Set `servers` - generate servers of a schema file
RSpec::OpenAPI.servers = [{ url: 'http://localhost:3000' }]

# Set `security_schemes` - generate security schemes
RSpec::OpenAPI.security_schemes = {
'MyToken' => {
description: 'Authenticate API requests via a JWT',
type: 'http',
scheme: 'bearer',
bearerFormat: 'JWT',
},
}

# Generate a comment on top of a schema file
RSpec::OpenAPI.comment = <<~EOS
This file is auto-generated by rspec-openapi https://github.com/k0kubun/rspec-openapi

When you write a spec in spec/requests, running the spec with `OPENAPI=1 rspec` will
update this file automatically. You can also manually edit this file.
EOS

# Generate a custom description, given an RSpec example
RSpec::OpenAPI.description_builder = -> (example) { example.description }

# Generate a custom summary, given an RSpec example
# This example uses the summary from the example_group.
RSpec::OpenAPI.summary_builder = ->(example) { example.metadata.dig(:example_group, :openapi, :summary) }

# Generate a custom tags, given an RSpec example
# This example uses the tags from the parent_example_group
RSpec::OpenAPI.tags_builder = -> (example) { example.metadata.dig(:example_group, :parent_example_group, :openapi, :tags) }

# Change the example type(s) that will generate schema
RSpec::OpenAPI.example_types = %i[request]

# Configure which path params to ignore
# :controller and :action always exist. :format is added when routes is configured as such.
RSpec::OpenAPI.ignored_path_params = %i[controller action format]

# Configure which paths to ignore.
# You can exclude some specs via `openapi: false`.
# But, in a complex API usage scenario, you may need to include spec itself, but exclude some private paths.
# In that case, you can specify the paths to ignore.
# String or Regexp is acceptable.
RSpec::OpenAPI.ignored_paths = ["/admin/full/path/", Regexp.new("^/_internal/")]

# Your custom post-processing hook (like unrandomizing IDs)
RSpec::OpenAPI.post_process_hook = -> (path, records, spec) do
RSpec::OpenAPI::HashHelper.matched_paths(spec, 'paths.*.*.responses.*.content.*.*.*.id').each do |paths|
spec.dig(*paths[0..-2]).merge!(id: '123')
end
end
```

### Can I use rspec-openapi with `$ref` to minimize duplication of schema?

Yes, rspec-openapi v0.7.0+ supports [`$ref` mechanism](https://swagger.io/docs/specification/using-ref/) and generates
schemas under `#/components/schemas` with some manual steps.

1. First, generate plain OpenAPI file.
2. Then, manually replace the duplications with `$ref`.

```yaml
paths:
"/users":
get:
responses:
'200':
content:
application/json:
schema:
type: array
items:
$ref: "#/components/schemas/User"
"/users/{id}":
get:
responses:
'200':
content:
application/json:
schema:
$ref: "#/components/schemas/User"
# Note) #/components/schemas is not needed to be defined.
```

3. Then, re-run rspec-openapi. It will generate `#/components/schemas` with the referenced schema (`User` for example) newly-generated or updated.

```yaml
paths:
"/users":
get:
responses:
'200':
content:
application/json:
schema:
type: array
items:
$ref: "#/components/schemas/User"
"/users/{id}":
get:
responses:
'200':
content:
application/json:
schema:
$ref: "#/components/schemas/User"
components:
schemas:
User:
type: object
properties:
id:
type: string
name:
type: string
role:
type: array
items:
type: string
```

rspec-openapi also supports `$ref` in `properties` of schemas. Example)

```yaml
paths:
"/locations":
get:
responses:
'200':
content:
application/json:
schema:
type: array
items:
$ref: "#/components/schemas/Location"
components:
schemas:
Location:
type: object
properties:
id:
type: string
name:
type: string
Coordinate:
"$ref": "#/components/schemas/Coordinate"
Coordinate:
type: object
properties:
lat:
type: string
lon:
type: string
```

Note that automatic `schemas` update feature is still new and may not work in complex scenario.
If you find a room for improvement, open an issue.

### How can I add information which can't be generated from RSpec?

rspec-openapi tries to preserve manual modifications as much as possible when generating specs.
You can directly edit `doc/openapi.yaml` as you like without spoiling the automatic generation capability.

### Can I exclude specific specs from OpenAPI generation?

Yes, you can specify `openapi: false` to disable the automatic generation.

```rb
RSpec.describe '/resources', type: :request, openapi: false do
# ...
end

# or

RSpec.describe '/resources', type: :request do
it 'returns a resource', openapi: false do
# ...
end
end
```

## Customizations

Some examples' attributes can be overwritten via RSpec metadata options. Example:

```rb
describe 'GET /api/v1/posts', openapi: {
summary: 'list all posts',
description: 'list all posts ordered by pub_date',
tags: %w[v1 posts],
required_request_params: %w[limit],
security: [{"MyToken" => []}],
} do
# ...
end
```

**NOTE**: `description` key will override also the one provided by `RSpec::OpenAPI.description_builder` method.

## Experimental minitest support

Even if you are not using `rspec` this gem might help you with its experimental support for `minitest`.

Example:

```rb
class TablesTest < ActionDispatch::IntegrationTest
openapi!

test "GET /index returns a list of tables" do
get '/tables', params: { page: '1', per: '10' }, headers: { authorization: 'k0kubun' }
assert_response :success
end

test "GET /index does not return tables if unauthorized" do
get '/tables'
assert_response :unauthorized
end

# ...
end
```

It should work with both classes inheriting from `ActionDispatch::IntegrationTest` and with classes using `Rack::Test` directly, as long as you call `openapi!` in your test class.

Please note that not all features present in the rspec integration work with minitest (yet). For example, custom per test case metadata is not supported. A custom `description_builder` will not work either.

Run minitest with OPENAPI=1 to generate `doc/openapi.yaml` for your request specs.

```bash
$ OPENAPI=1 bundle exec rails t
```

## Links

Existing RSpec plugins which have OpenAPI integration:

* [zipmark/rspec\_api\_documentation](https://github.com/zipmark/rspec_api_documentation)
* [rswag/rswag](https://github.com/rswag/rswag)
* [drewish/rspec-rails-swagger](https://github.com/drewish/rspec-rails-swagger)

## Acknowledgements

* Heavily inspired by [r7kamura/autodoc](https://github.com/r7kamura/autodoc)
* Orignally created by [k0kubun](https://github.com/k0kubun) and the ownership was transferred to [exoego](https://github.com/exoego) in 2022-11-29.

## License

The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).