feat: error for non-object request bodies (#288)

docs/spectral-rules.md

@@ -145,6 +145,35 @@ parameters:
 
 **Default Severity**: error
 
+## request-body-object
+
+Request bodies should be objects.
+
+**Bad Example**
+
+```yaml
+requestBody:
+  content:
+    application/json:
+      schema:
+        type: string
+```
+
+**Good Example**
+
+```yaml
+requestBody:
+  content:
+    application/json:
+      schema:
+        type: object
+        properties:
+          prop1:
+            type: string
+```
+
+**Default Severity**: warn
+
 ## response-example-provided
 
 Response examples are used to generate documentation. To improve the generated documentation, response examples should be provided in the schema object or "next to" the schema object.

src/spectral/rulesets/.defaultsForSpectral.yaml

@@ -163,6 +163,17 @@ rules:
     resolved: true
     then:
       function: error-response-schema
+  # ensure requestBody is an object
+  request-body-object:
+    description: "All request bodies MUST be structured as an object"
+    given: $.paths[*][*].requestBody.content[*].schema
+    severity: error
+    then:
+      field: type
+      function: enumeration
+      functionOptions:
+        values:
+        - object
   # ensure major version is in path
   major-version-in-path:
     description: 'All paths must contain the API major version as a distinct path segment'

test/spectral/tests/custom-rules/request-body-object.test.js

@@ -0,0 +1,81 @@
+const inCodeValidator = require('../../../../src/lib');
+
+describe('spectral - test that request body schema is an object', function() {
+  it('should error only when request body is not an object', async () => {
+    const spec = {
+      openapi: '3.0.0',
+      paths: {
+        '/path1': {
+          post: {
+            operationId: 'addPet',
+            requestBody: {
+              content: {
+                'application/json': {
+                  schema: {
+                    // no error
+                    type: 'object',
+                    properties: {
+                      prop1: {
+                        type: 'string'
+                      }
+                    }
+                  }
+                }
+              }
+            }
+          },
+          put: {
+            operationId: 'updatePet',
+            requestBody: {
+              content: {
+                'application/json': {
+                  schema: {
+                    // error 1
+                    type: 'array',
+                    items: {
+                      type: 'string'
+                    }
+                  }
+                }
+              }
+            }
+          },
+          patch: {
+            operationId: 'patchPet',
+            requestBody: {
+              content: {
+                'application/json': {
+                  schema: {
+                    // no error, properties provided
+                    properties: {
+                      prop1: {
+                        type: 'string'
+                      }
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    };
+
+    const res = await inCodeValidator(spec, true);
+    const expectedErrors = res.errors.filter(
+      err =>
+        err.message === 'All request bodies MUST be structured as an object'
+    );
+    expect(expectedErrors.length).toBe(1);
+    expect(expectedErrors[0].path).toEqual([
+      'paths',
+      '/path1',
+      'put',
+      'requestBody',
+      'content',
+      'application/json',
+      'schema',
+      'type'
+    ]);
+  });
+});