Extracted TestAgent class for test utils

refs https://github.com/TryGhost/Toolbox/issues/214

- The constructor logic was duplicated across test agents, so made sence to extract the logic into a common class

test/utils/admin-api-test-agent.js

@@ -1,4 +1,4 @@
-const Agent = require('@tryghost/express-test');
+const TestAgent = require('./test-agent');
 const errors = require('@tryghost/errors');
 const DataGenerator = require('./fixtures/data-generator');
 
@@ -14,15 +14,9 @@ const ownerUser = {
  * @param {String} options.apiURL
  * @param {String} options.originURL
  */
-class AdminAPITestAgent extends Agent {
+class AdminAPITestAgent extends TestAgent {
     constructor(app, options) {
-        super(app, {
+        super(app, options);
-            baseUrl: options.apiURL,
-            headers: {
-                host: options.originURL.replace(/http:\/\//, ''),
-                origin: options.originURL
-            }
-        });
     }
 
     async loginAs(email, password) {

test/utils/members-api-test-agent.js

@@ -1,21 +1,18 @@
-const Agent = require('@tryghost/express-test');
+const TestAgent = require('./test-agent');
 
 /**
+ * NOTE: this class is not doing much at the moment. It's rather a placeholder to put
+ * any Members API specific functionality into. If there is none in the nearest
+ * future, it would make sense to remove it alltogether.
  * @constructor
  * @param {Object} app  Ghost express app instance
  * @param {Object} options
  * @param {String} options.apiURL
  * @param {String} options.originURL
  */
-class MembersAPITestAgent extends Agent {
+class MembersAPITestAgent extends TestAgent {
     constructor(app, options) {
-        super(app, {
+        super(app, options);
-            baseUrl: options.apiURL,
-            headers: {
-                host: options.originURL.replace(/http:\/\//, ''),
-                origin: options.originURL
-            }
-        });
     }
 }
 

test/utils/test-agent.js

@@ -0,0 +1,22 @@
+const Agent = require('@tryghost/express-test');
+
+/**
+ * @constructor
+ * @param {Object} app  Ghost express app instance
+ * @param {Object} options
+ * @param {String} options.apiURL
+ * @param {String} options.originURL
+ */
+class TestAgent extends Agent {
+    constructor(app, options) {
+        super(app, {
+            baseUrl: options.apiURL,
+            headers: {
+                host: options.originURL.replace(/http:\/\//, ''),
+                origin: options.originURL
+            }
+        });
+    }
+}
+
+module.exports = TestAgent;