diff --git a/src/DefinitionGenerator.ts b/src/DefinitionGenerator.ts
index 5aef836..48eebc8 100644
--- a/src/DefinitionGenerator.ts
+++ b/src/DefinitionGenerator.ts
@@ -174,13 +174,11 @@ export class DefinitionGenerator {
       operationObj.deprecated = true;
     }
 
-    if (operationObj.requestBody) {
+    if (documentationConfig.requestBody) {
       operationObj.requestBody = this.getRequestBodiesFromConfig(documentationConfig);
     }
 
-    if (operationObj.parameters) {
-      operationObj.parameters = this.getParametersFromConfig(documentationConfig);
-    }
+    operationObj.parameters = this.getParametersFromConfig(documentationConfig);
 
     operationObj.responses = this.getResponsesFromConfig(documentationConfig);
 
diff --git a/src/__tests__/DefinitionGenerator.spec.ts b/src/__tests__/DefinitionGenerator.spec.ts
index 2004ae6..9490410 100644
--- a/src/__tests__/DefinitionGenerator.spec.ts
+++ b/src/__tests__/DefinitionGenerator.spec.ts
@@ -1,6 +1,7 @@
 import * as path from 'path';
 import * as Serverless from 'serverless';
 import { DefinitionGenerator } from '../DefinitionGenerator';
+import { merge } from '../utils';
 
 class ServerlessInterface extends Serverless {
   public service: any = {};
@@ -11,10 +12,12 @@ class ServerlessInterface extends Serverless {
 }
 
 describe('OpenAPI Documentation Generator', () => {
-  it('Generates OpenAPI document', async () => {
+  let sls: ServerlessInterface;
+
+  beforeEach(async () => {
     const servicePath = path.join(__dirname, '../../test/project');
     const serverlessYamlPath = path.join(servicePath, './serverless.yml');
-    const sls: ServerlessInterface = new Serverless();
+    sls = new Serverless();
 
     sls.config.update({
       servicePath,
@@ -26,12 +29,67 @@ describe('OpenAPI Documentation Generator', () => {
     await sls.service.load(config);
     await sls.variables.populateService();
 
-    if ('documentation' in sls.service.custom) {
-      const docGen = new DefinitionGenerator(sls.service.custom.documentation);
-
-      expect(docGen).not.toBeNull();
-    } else {
+    if (!('documentation' in sls.service.custom)) {
       throw new Error('Cannot find "documentation" in custom section of "serverless.yml"');
     }
   });
+
+  it('Generates OpenAPI document', async () => {
+    const docGen = new DefinitionGenerator(sls.service.custom.documentation);
+    expect(docGen).not.toBeNull();
+  });
+
+  it('adds paths to OpenAPI output from function configuration', async () => {
+    const docGen = new DefinitionGenerator(sls.service.custom.documentation);
+
+    // implementation copied from ServerlessOpenApiDocumentation.ts
+    docGen.parse();
+
+    const funcConfigs = sls.service.getAllFunctions().map((functionName) => {
+      const func = sls.service.getFunction(functionName);
+      return merge({ _functionName: functionName }, func);
+    });
+
+    docGen.readFunctions(funcConfigs);
+
+    // get the parameters from the `/create POST' endpoint
+    const actual = docGen.definition.paths['/create'].post.parameters;
+    const expected = [
+      {
+        description: 'The username for a user to create',
+        in: 'path',
+        name: 'username',
+        required: true,
+        schema: {
+          pattern: '^[-a-z0-9_]+$',
+          type: 'string',
+        },
+      },
+      {
+        allowEmptyValue: false,
+        description: `The user's Membership Type`,
+        in: 'query',
+        name: 'membershipType',
+        required: false,
+        schema: {
+          enum: [
+            'premium',
+            'standard',
+          ],
+          type: 'string',
+        },
+      },
+      {
+        description: 'A Session ID variable',
+        in: 'cookie',
+        name: 'SessionId',
+        required: false,
+        schema: {
+          type: 'string',
+        },
+      },
+    ];
+
+    expect(actual).toEqual(expected);
+  });
 });