add some superagent tests

src/superagent.js

@@ -31,7 +31,6 @@ class Request {
         this.okFunc = (response) => response.ok;
         this.timer = { timeout: 0, id: null, controller: null };
         this.retryCount = 0;
-        this.fetchOptions.headers.set('Content-Type', 'application/json');
     }
 
     async _makeRequest() {
@@ -101,7 +100,7 @@ class Request {
 
     send(data) {
         const contentType = this.fetchOptions.headers.get('Content-Type');
-        if (contentType === 'application/json') {
+        if (!contentType || contentType === 'application/json') {
             this.fetchOptions.headers.set('Content-Type', 'application/json');
             this.fetchOptions.body = JSON.stringify(data);
         } else if (contentType === 'application/x-www-form-urlencoded') {

src/test/superagent-test.js

@@ -0,0 +1,25 @@
+/* global it:false */
+/* global describe:false */
+/* global before:false */
+
+'use strict';
+
+const expect = require('expect.js'),
+    safe = require('safetydance'),
+    superagent = require('../superagent.js');
+
+describe('Superagent', function () {
+    it('can get URL', async function () {
+        await superagent.get('https://www.cloudron.io').set('User-Agent', 'Mozilla').timeout(10*1000);
+    });
+
+    it('follows redirect', async function () {
+        const response = await superagent.get('https://cloudron.io').set('User-Agent', 'Mozilla').timeout(10*1000);
+        expect(response.url).to.be('https://www.cloudron.io/');
+    });
+
+    it('can disable redirects', async function () {
+        const [error] = await safe(superagent.get('https://cloudron.io').set('User-Agent', 'Mozilla').timeout(10*1000).redirects(0));
+        expect(error).to.be.ok();
+    });
+});