Update enzyme from 2.8.2 to 3.7.0

enzyme calls componentDidMount() by default as of v3.
* https://github.com/airbnb/enzyme/blob/master/CHANGELOG.md#breaking-changes
* enzymejs/enzyme#1140

package.json

@@ -53,6 +53,7 @@
   },
   "homepage": "http://www.gitify.io/",
   "jest": {
+    "setupTestFrameworkScriptFile": "<rootDir>src/js/setup-tests.js",
     "coverageThreshold": {
       "global": {
         "lines": 95
@@ -101,7 +102,8 @@
     "browserify": "=14.4.0",
     "electron": "=1.6.10",
     "electron-packager": "=8.7.0",
-    "enzyme": "=2.8.2",
+    "enzyme": "=3.7.0",
+    "enzyme-adapter-react-15": "^1.1.1",
     "eslint": "=3.19.0",
     "eslint-config-dabapps": "github:dabapps/eslint-config-dabapps#v3.1.1",
     "eslint-plugin-import": "=2.3.0",

src/js/__tests__/components/settings-modal.js

@@ -70,7 +70,6 @@ describe('components/settings-modal.js', () => {
     const wrapper = shallow(<SettingsModal {...props} />);
     expect(wrapper).toBeDefined();
 
-    wrapper.instance().componentDidMount();
     expect(props.toggleSettingsModal).toHaveBeenCalledTimes(1);
 
     wrapper.instance().componentWillUnmount();

src/js/__tests__/components/sidebar.js

@@ -107,7 +107,6 @@ describe('components/Sidebar.js', () => {
 
     expect(wrapper).toBeDefined();
 
-    wrapper.instance().componentDidMount();
     clock.runTimersToTime(60000);
     expect(props.fetchNotifications).toHaveBeenCalledTimes(1);
   });

src/js/setup-tests.js

@@ -0,0 +1,4 @@
+import { configure } from 'enzyme';
+import Adapter from 'enzyme-adapter-react-15';
+
+configure({ adapter: new Adapter() });