make snapshot tests explicit in each component

closes #196

components/x-increment/__tests__/__snapshots__/x-increment.test.jsx.snap

@@ -0,0 +1,29 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`x-increment snapshots renders a default Async nodejs 1`] = `
+<div>
+  <span>
+    1
+  </span>
+  <button
+    disabled={false}
+    onClick={[Function]}
+  >
+    Increment
+  </button>
+</div>
+`;
+
+exports[`x-increment snapshots renders a default Increment nodejs 1`] = `
+<div>
+  <span>
+    1
+  </span>
+  <button
+    disabled={false}
+    onClick={[Function]}
+  >
+    Increment
+  </button>
+</div>
+`;

components/x-increment/__tests__/x-increment.test.jsx

@@ -1,5 +1,7 @@
 const { h } = require('@financial-times/x-engine');
 const { mount } = require('@financial-times/x-test-utils/enzyme');
+const snapshots = require('@financial-times/x-test-utils/snapshots');
+const stories = require('../stories');
 
 const { Increment } = require('../');
 
@@ -27,4 +29,8 @@ describe('x-increment', () => {
 		expect(Date.now() - start).toBeCloseTo(1000, -2); // negative precision ⇒ left of decimal point
 		expect(subject.find('span').text()).toEqual('2');
 	});
+
+	describe('snapshots', () => {
+		snapshots(stories);
+	})
 });

components/x-styling-demo/__tests__/__snapshots__/x-styling-demo.test.jsx.snap

@@ -0,0 +1,9 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`x-styling-demo renders a default Styling nodejs 1`] = `
+<button
+  className="Button_button__vS7Mv"
+>
+  Click me!
+</button>
+`;

components/x-styling-demo/__tests__/x-styling-demo.test.jsx

@@ -0,0 +1,6 @@
+const snapshots = require('@financial-times/x-test-utils/snapshots');
+const stories = require('../stories');
+
+describe('x-styling-demo', () => {
+	snapshots(stories);
+});