feat: add prefer example implementation

lib/mocker/express/server.js

@@ -8,6 +8,7 @@ const cors = require('cors');
 const cookieParser = require('cookie-parser');
 const logger = require('lllog')();
 const colors = require('colors');
+const parsePreferHeader = require('parse-prefer-header');
 
 const openApiMockSymbol = Symbol('openApiMock');
 
@@ -95,14 +96,14 @@ class Server {
 					return this.sendResponse(res, { errors: failedValidations }, 400);
 
 				const preferHeader = req.header('prefer') || '';
-				const [, preferStatusCode] = preferHeader.match(/statusCode=(\d{3})/) || [];
+				const { example: preferredExampleName, statusCode: preferredStatusCode } = parsePreferHeader(preferHeader) || {};
 
-				if(preferStatusCode)
-					logger.debug(`Searching requested response with status code ${preferStatusCode}`);
+				if(preferredStatusCode)
+					logger.debug(`Searching requested response with status code ${preferredStatusCode}`);
 				else
 					logger.debug('Searching first response');
 
-				const { statusCode, headers: responseHeaders, body } = path.getResponse(preferStatusCode);
+				const { statusCode, headers: responseHeaders, body } = path.getResponse(preferredStatusCode, preferredExampleName);
 
 				return this.sendResponse(res, body, statusCode, responseHeaders);
 			});

lib/paths/path.js

@@ -209,7 +209,7 @@ class Path {
 		return !possibleValues || !possibleValues.length || possibleValues.includes(value);
 	}
 
-	getResponse(preferredStatusCode) {
+	getResponse(preferredStatusCode, preferredExampleName) {
 
 		const {
 			statusCode,
@@ -220,7 +220,7 @@ class Path {
 		return {
 			statusCode: Number(statusCode),
 			headers: headers && this.generateResponseHeaders(headers),
-			body: schema ? ResponseGenerator.generate(schema) : null
+			body: schema ? ResponseGenerator.generate(schema, preferredExampleName) : null
 		};
 	}
 

lib/response-generator/index.js

@@ -2,13 +2,16 @@
 
 class ResponseGenerator {
 
-	static generate(schemaResponse) {
+	static generate(schemaResponse, preferredExampleName) {
 
 		if(schemaResponse.example)
 			return schemaResponse.example;
 
-		if(schemaResponse.examples && schemaResponse.examples.length)
+		if(schemaResponse.examples && Object.values(schemaResponse.examples).length) {
+			if(preferredExampleName)
+				return schemaResponse.examples[preferredExampleName] || Object.values(schemaResponse.examples)[0];
 			return schemaResponse.examples[0];
+		}
 
 		if(schemaResponse.enum && schemaResponse.enum.length)
 			return this.generateByEnum(schemaResponse.enum);

package.json

@@ -48,6 +48,7 @@
     "js-yaml": "^3.14.0",
     "json-refs": "^3.0.13",
     "lllog": "^1.1.2",
+    "parse-prefer-header": "^1.0.0",
     "superstruct": "^0.6.1",
     "yargs": "^13.3.0"
   },

tests/paths/path.js

@@ -1803,6 +1803,78 @@ describe('Paths', () => {
 			});
 		});
 
+		it('Should call the response generator with the first available response with given example if no preferred statusCode is passed', () => {
+
+			const path = new Path({
+				uri: '/hello',
+				httpMethod: 'get',
+				parameters: undefined,
+				responses: {
+					200: {
+						description: 'OK',
+						content: {
+							'application/json': {
+								examples: {
+									hello: {
+										message: 'world'
+									},
+									goodbye: {
+										message: 'yellow brick road'
+									}
+								}
+							}
+						}
+					}
+				}
+			});
+
+			const response = path.getResponse(undefined, 'goodbye');
+
+			assert.deepStrictEqual(response, {
+				statusCode: 200,
+				headers: undefined,
+				body: {
+					message: 'yellow brick road'
+				}
+			});
+		});
+
+		it('Should call the response generator with the first available response with prefer example & no prefered statusCode, but no match', () => {
+
+			const path = new Path({
+				uri: '/hello',
+				httpMethod: 'get',
+				parameters: undefined,
+				responses: {
+					200: {
+						description: 'OK',
+						content: {
+							'application/json': {
+								examples: {
+									hello: {
+										message: 'world'
+									},
+									goodbye: {
+										message: 'yellow brick road'
+									}
+								}
+							}
+						}
+					}
+				}
+			});
+
+			const response = path.getResponse(undefined, 'sup');
+
+			assert.deepStrictEqual(response, {
+				statusCode: 200,
+				headers: undefined,
+				body: {
+					message: 'world'
+				}
+			});
+		});
+
 		it('Should call the response generator with the preferred response based on the passed statusCode', () => {
 
 			const path = new Path({
@@ -1844,6 +1916,52 @@ describe('Paths', () => {
 			});
 		});
 
+		it('Should call the response generator with the preferred response based on the passed statusCode and passed example', () => {
+
+			const path = new Path({
+				uri: '/hello',
+				httpMethod: 'get',
+				parameters: undefined,
+				responses: {
+					200: {
+						description: 'OK',
+						content: {
+							'application/json': {
+								example: {
+									hello: 'world'
+								}
+							}
+						}
+					},
+					401: {
+						description: 'Unauthorized',
+						content: {
+							'application/json': {
+								examples: {
+									invalid: {
+										message: 'Unauthorized - token invalid'
+									},
+									expired: {
+										message: 'Unauthorized - token expired'
+									}
+								}
+							}
+						}
+					}
+				}
+			});
+
+			const response = path.getResponse('401', 'expired');
+
+			assert.deepStrictEqual(response, {
+				statusCode: 401,
+				headers: undefined,
+				body: {
+					message: 'Unauthorized - token expired'
+				}
+			});
+		});
+
 		it('Should call the response generator with the first response if preferred response is not available', () => {
 
 			const path = new Path({

tests/response-generator/index.js

@@ -38,6 +38,47 @@ describe('Response Generator', () => {
 			});
 		});
 
+		it('Should return the preferred example if prefer header is set', () => {
+
+			const responseSchema = {
+				examples: {
+					cat: {
+						summary: 'An example of a cat',
+						value: {
+							name: 'Fluffy',
+							petType: 'Cat',
+							color: 'White',
+							gender: 'male',
+							breed: 'Persian'
+						}
+					},
+					dog: {
+						summary: 'An example of a dog with a cat\'s name',
+						value: {
+							name: 'Puma',
+							petType: 'Dog',
+							color: 'Black',
+							gender: 'Female',
+							breed: 'Mixed'
+						}
+					}
+				}
+			};
+
+			const response = ResponseGenerator.generate(responseSchema, 'cat');
+
+			assert.deepStrictEqual(response, {
+				summary: 'An example of a cat',
+				value: {
+					name: 'Fluffy',
+					petType: 'Cat',
+					color: 'White',
+					gender: 'male',
+					breed: 'Persian'
+				}
+			});
+		});
+
 		it('Should return the schema\'s example if it\'s defined', () => {
 
 			const responseSchema = {