🎉 [new rule] relay-connection-types, relay-edge-types, relay-page-info, relay-arguments (#982)

* add create-rule script and dummy rule

* add changeset

* update snapshots after rebase

* [relay-page-info]: allow scalar for startCursor/endCursor

* refactor

* improve types

* add `relay-arguments`

* add includeBoth option

* run test with ruletester before snapshots tests

* refactor

Author: dimaMachina

.changeset/ninety-seas-beg.md

@@ -0,0 +1,5 @@
+---
+'@graphql-eslint/eslint-plugin': minor
+---
+
+feat: add `relay-connection-types`, `relay-edge-types`, `relay-page-info` and `relay-arguments` rules

.eslintrc.js

@@ -27,6 +27,7 @@ module.exports = {
     'unicorn/no-useless-fallback-in-spread': 'error',
     'unicorn/better-regex': 'error',
     'prefer-destructuring': ['error', { object: true }],
+    quotes: ['error', 'single', { avoidEscape: true }], // Matches Prettier, but also replaces backticks
   },
   overrides: [
     {

README.md

@@ -193,6 +193,7 @@ See [docs/deprecated-rules.md](docs/deprecated-rules.md).
 |[`schema-all`](packages/plugin/src/configs/schema-all.json)|enables all rules for schema (SDL) development, except for those that require `parserOptions.operations` option|
 |[`operations-recommended`](packages/plugin/src/configs/operations-recommended.json) |enables recommended rules for consuming GraphQL (operations) development|
 |[`operations-all`](packages/plugin/src/configs/operations-all.json)|enables all rules for consuming GraphQL (operations) development|
+|[`relay`](packages/plugin/src/configs/relay.json)|enables rules from Relay specification for schema (SDL) development|
 <!-- prettier-ignore-end -->
 
 > If you are in a project that develops the GraphQL schema, you'll need `schema` rules. 

docs/README.md

@@ -44,6 +44,10 @@ Name            &nbs
 [possible-fragment-spread](rules/possible-fragment-spread.md)|A fragment spread is only valid if the type condition could ever possibly be true: if there is a non-empty intersection of the possible parent types, and possible types which pass the type condition.|![recommended][]|🔮|
 [possible-type-extension](rules/possible-type-extension.md)|A type extension is only valid if the type is defined and has the same kind.||🔮|
 [provided-required-arguments](rules/provided-required-arguments.md)|A field or directive is only valid if all required (non-null without a default value) field arguments have been provided.|![recommended][]|🔮|
+[relay-arguments](rules/relay-arguments.md)|Set of rules to follow Relay specification for Arguments.||🚀|
+[relay-connection-types](rules/relay-connection-types.md)|Set of rules to follow Relay specification for Connection types.||🚀|
+[relay-edge-types](rules/relay-edge-types.md)|Set of rules to follow Relay specification for Edge types.||🚀|
+[relay-page-info](rules/relay-page-info.md)|Set of rules to follow Relay specification for `PageInfo` object.||🚀|
 [require-deprecation-date](rules/require-deprecation-date.md)|Require deletion date on `@deprecated` directive. Suggest removing deprecated things after deprecated date.|![all][]|🚀|💡
 [require-deprecation-reason](rules/require-deprecation-reason.md)|Require all deprecation directives to specify a reason.|![recommended][]|🚀|
 [require-description](rules/require-description.md)|Enforce descriptions in type definitions and operations.|![recommended][]|🚀|

docs/custom-rules.md

@@ -118,7 +118,7 @@ export const rule = {
 }
 ```
 
-The structure of the return value of `.typeInfo()` is [defined here](https://github.com/B2o5T/graphql-eslint/blob/master/packages/plugin/src/estree-parser/converter.ts#L63-L71). So based on the `node` you are using, you'll get a different values on `.typeInfo()` result.
+The structure of the return value of `.typeInfo()` is [defined here](https://github.com/B2o5T/graphql-eslint/blob/master/packages/plugin/src/estree-parser/converter.ts#L32-L40). So based on the `node` you are using, you'll get a different values on `.typeInfo()` result.
 
 ## Testing your rules
 

docs/rules/relay-arguments.md

@@ -0,0 +1,57 @@
+# `relay-arguments`
+
+- Category: `Schema`
+- Rule name: `@graphql-eslint/relay-arguments`
+- Requires GraphQL Schema: `false` [ℹ️](../../README.md#extended-linting-rules-with-graphql-schema)
+- Requires GraphQL Operations: `false` [ℹ️](../../README.md#extended-linting-rules-with-siblings-operations)
+
+Set of rules to follow Relay specification for Arguments.
+
+- A field that returns a Connection type must include forward pagination arguments (`first` and `after`), backward pagination arguments (`last` and `before`), or both
+
+Forward pagination arguments
+
+- `first` takes a non-negative integer
+- `after` takes the Cursor type
+
+Backward pagination arguments
+
+- `last` takes a non-negative integer
+- `before` takes the Cursor type
+
+## Usage Examples
+
+### Incorrect
+
+```graphql
+# eslint @graphql-eslint/relay-arguments: 'error'
+
+type User {
+  posts: PostConnection
+}
+```
+
+### Correct
+
+```graphql
+# eslint @graphql-eslint/relay-arguments: 'error'
+
+type User {
+  posts(after: String, first: Int, before: String, last: Int): PostConnection
+}
+```
+
+## Config Schema
+
+The schema defines the following properties:
+
+### `includeBoth` (boolean)
+
+Enforce including both forward and backward pagination arguments
+
+Default: `true`
+
+## Resources
+
+- [Rule source](../../packages/plugin/src/rules/relay-arguments.ts)
+- [Test source](../../packages/plugin/tests/relay-arguments.spec.ts)

docs/rules/relay-connection-types.md

@@ -0,0 +1,42 @@
+# `relay-connection-types`
+
+- Category: `Schema`
+- Rule name: `@graphql-eslint/relay-connection-types`
+- Requires GraphQL Schema: `false` [ℹ️](../../README.md#extended-linting-rules-with-graphql-schema)
+- Requires GraphQL Operations: `false` [ℹ️](../../README.md#extended-linting-rules-with-siblings-operations)
+
+Set of rules to follow Relay specification for Connection types.
+
+- Any type whose name ends in "Connection" is considered by spec to be a `Connection type`
+- Connection type must be an Object type
+- Connection type must contain a field `edges` that return a list type which wraps an edge type
+- Connection type must contain a field `pageInfo` that return a non-null `PageInfo` Object type
+
+## Usage Examples
+
+### Incorrect
+
+```graphql
+# eslint @graphql-eslint/relay-connection-types: 'error'
+
+type UserPayload { # should be an Object type with `Connection` suffix
+  edges: UserEdge! # should return a list type
+  pageInfo: PageInfo # should return a non-null `PageInfo` Object type
+}
+```
+
+### Correct
+
+```graphql
+# eslint @graphql-eslint/relay-connection-types: 'error'
+
+type UserConnection {
+  edges: [UserEdge]
+  pageInfo: PageInfo!
+}
+```
+
+## Resources
+
+- [Rule source](../../packages/plugin/src/rules/relay-connection-types.ts)
+- [Test source](../../packages/plugin/tests/relay-connection-types.spec.ts)

docs/rules/relay-edge-types.md

@@ -0,0 +1,56 @@
+# `relay-edge-types`
+
+- Category: `Schema`
+- Rule name: `@graphql-eslint/relay-edge-types`
+- Requires GraphQL Schema: `true` [ℹ️](../../README.md#extended-linting-rules-with-graphql-schema)
+- Requires GraphQL Operations: `false` [ℹ️](../../README.md#extended-linting-rules-with-siblings-operations)
+
+Set of rules to follow Relay specification for Edge types.
+
+- A type that is returned in list form by a connection type's `edges` field is considered by this spec to be an Edge type
+- Edge type must be an Object type
+- Edge type must contain a field `node` that return either a Scalar, Enum, Object, Interface, Union, or a non-null wrapper around one of those types. Notably, this field cannot return a list
+- Edge type must contain a field `cursor` that return a String, Scalar, or a non-null wrapper wrapper around one of those types
+- Edge type name must end in "Edge" _(optional)_
+- Edge type's field `node` must implement `Node` interface _(optional)_
+- A list type should only wrap an edge type _(optional)_
+
+## Usage Examples
+
+### Correct
+
+```graphql
+# eslint @graphql-eslint/relay-edge-types: 'error'
+
+type UserConnection {
+  edges: [UserEdge]
+  pageInfo: PageInfo!
+}
+```
+
+## Config Schema
+
+The schema defines the following properties:
+
+### `withEdgeSuffix` (boolean)
+
+Edge type name must end in "Edge".
+
+Default: `true`
+
+### `shouldImplementNode` (boolean)
+
+Edge type's field `node` must implement `Node` interface.
+
+Default: `true`
+
+### `listTypeCanWrapOnlyEdgeType` (boolean)
+
+A list type should only wrap an edge type.
+
+Default: `true`
+
+## Resources
+
+- [Rule source](../../packages/plugin/src/rules/relay-edge-types.ts)
+- [Test source](../../packages/plugin/tests/relay-edge-types.spec.ts)

docs/rules/relay-page-info.md

@@ -0,0 +1,32 @@
+# `relay-page-info`
+
+- Category: `Schema`
+- Rule name: `@graphql-eslint/relay-page-info`
+- Requires GraphQL Schema: `true` [ℹ️](../../README.md#extended-linting-rules-with-graphql-schema)
+- Requires GraphQL Operations: `false` [ℹ️](../../README.md#extended-linting-rules-with-siblings-operations)
+
+Set of rules to follow Relay specification for `PageInfo` object.
+
+- `PageInfo` must be an Object type
+- `PageInfo` must contain fields `hasPreviousPage` and `hasNextPage`, which return non-null Boolean
+- `PageInfo` must contain fields `startCursor` and `endCursor`, which return non-null String or Scalar
+
+## Usage Examples
+
+### Correct
+
+```graphql
+# eslint @graphql-eslint/relay-page-info: 'error'
+
+type PageInfo {
+  hasPreviousPage: Boolean!
+  hasNextPage: Boolean!
+  startCursor: String!
+  endCursor: String!
+}
+```
+
+## Resources
+
+- [Rule source](../../packages/plugin/src/rules/relay-page-info.ts)
+- [Test source](../../packages/plugin/tests/relay-page-info.spec.ts)

docs/rules/strict-id-in-types.md

@@ -78,6 +78,7 @@ Default:
 
 Additional restrictions:
 
+* Minimum items: `1`
 * Unique items: `true`
 
 ### `acceptedIdTypes` (array)
@@ -94,6 +95,7 @@ Default:
 
 Additional restrictions:
 
+* Minimum items: `1`
 * Unique items: `true`
 
 ### `exceptions` (object)