Add JSON Schema misconfigurations rules (#33)

* Add JSON Schema misconfigurations rules

* adjust rules so problems point to the key instead of the value

* fix rules and readme

* add newline

Co-authored-by: Andrew Tatomyr <[email protected]>

---------

Co-authored-by: Andrew Tatomyr <[email protected]>

README.md

@@ -43,6 +43,7 @@ There are some fantastic examples of [configurable rules](https://redocly.com/do
 - [Paths should not match a pattern](configurable-rules/path-excludes-pattern/)
 - [API healthcheck rules](configurable-rules/api-health/)
 - [String schemas length defined](configurable-rules/string-schemas-length-defined/)
+- [JSON Schema misconfigurations](configurable-rules/json-schema-misconfigurations/)
 
 ### Custom plugins
 

configurable-rules/json-schema-misconfigurations/README.md

@@ -0,0 +1,113 @@
+# JSON Schema misconfigurations
+
+Authors:
+- [`adamaltman`](https://github.com/adamaltman) Adam Altman (Redocly)
+
+## What this does and why
+
+This catches common misconfigurations of JSON Schema:
+- disallows `minimum` or `maximum` values for a string (these are more logical for a number)
+- disallows `items` on an object (instead of an array)
+- disallows `properties` on an array (instead of items)
+
+## Code
+
+The first rule checks that a string isn't using the `minimum` and `maximum` keywords.
+```yaml
+  rule/json-schema-string-misconfiguration:
+    subject: 
+      type: Schema
+    where: 
+      - subject: 
+          type: Schema
+          property: type
+        assertions:  
+          const: string
+    assertions: 
+      disallowed: 
+        - minimum
+        - maximum
+```
+
+The second rule checks that an array isn't using the `properties` keyword.
+```yaml
+  rule/json-schema-array-misconfiguration:
+    subject: 
+      type: Schema
+    where: 
+      - subject: 
+          type: Schema
+          property: type
+        assertions:  
+          const: array
+    assertions: 
+      disallowed: 
+        - properties
+```
+
+The third rule checks that an object isn't using the `items` keyword.
+```yaml
+  rule/json-schema-object-misconfiguration:
+    subject: 
+      type: Schema
+    where: 
+      - subject: 
+          type: Schema
+          property: type
+        assertions:  
+          const: object
+    assertions: 
+      disallowed:  
+        - items
+```
+
+## Examples
+
+The following OpenAPI has schemas prefixed with either `Good` or `Bad` to show the configurable rules catch the likely bad uses of keywords.
+
+```yaml
+openapi: 3.1.0
+info: 
+  title: Unintended schema misconfigurations
+  version: 1.0.0
+paths: {}
+components: 
+  schemas: 
+
+    BadString:
+      type: string
+      minimum: 5
+      maximum: 10
+
+    GoodNumber:
+      type: number
+      minimum: 5
+      maximum: 10
+        
+    GoodString:
+      type: string
+      minLength: 5
+      maxLength: 10
+  
+    BadObject:
+      type: object
+      items: 
+        type: string
+    
+    GoodObject:
+      type: object
+      properties:
+        foo:
+          $ref: "#/components/schemas/GoodString"
+    
+    BadArray:
+      type: array
+      properties: 
+        foo:
+          $ref: "#/components/schemas/GoodString"
+```
+
+
+## References
+
+Inspired by a question in the "APIs You Won't Hate" Slack community (special thanks to Can Vural and Phil Sturgeon). 

configurable-rules/json-schema-misconfigurations/openapi.yaml

@@ -0,0 +1,39 @@
+openapi: 3.1.0
+info: 
+  title: Unintended schema misconfigurations
+  version: 1.0.0
+paths: {}
+components: 
+  schemas: 
+
+    BadString:
+      type: string
+      minimum: 5
+      maximum: 10
+
+    GoodNumber:
+      type: number
+      minimum: 5
+      maximum: 10
+
+    GoodString:
+      type: string
+      minLength: 5
+      maxLength: 10
+
+    BadObject:
+      type: object
+      items: 
+        type: string
+
+    GoodObject:
+      type: object
+      properties:
+        foo:
+          $ref: "#/components/schemas/GoodString"
+
+    BadArray:
+      type: array
+      properties: 
+        foo:
+          $ref: "#/components/schemas/GoodString"

configurable-rules/json-schema-misconfigurations/redocly.yaml

@@ -0,0 +1,38 @@
+rules:
+  rule/json-schema-string-misconfiguration:
+    subject: 
+      type: Schema
+    where: 
+      - subject: 
+          type: Schema
+          property: type
+        assertions:  
+          const: string
+    assertions: 
+      disallowed: 
+        - minimum
+        - maximum
+  rule/json-schema-array-misconfiguration:
+    subject: 
+      type: Schema
+    where: 
+      - subject: 
+          type: Schema
+          property: type
+        assertions:  
+          const: array
+    assertions: 
+      disallowed: 
+        - properties
+  rule/json-schema-object-misconfiguration:
+    subject: 
+      type: Schema
+    where: 
+      - subject: 
+          type: Schema
+          property: type
+        assertions:  
+          const: object
+    assertions: 
+      disallowed:  
+        - items