Allow Array to be deserialized from an Object

When an Array knob's value is serialized from the URL into the store, it
is an Object.

This ensures that when a user refreshes the page, the Array knob will
properly deserialize the Object into an Array.

addons/knobs/src/components/__tests__/Array.js

@@ -15,4 +15,21 @@ describe('Array', () => {
     wrapper.simulate('change', { target: { value: 'Fhishing,Skiing,Dancing' } });
     expect(onChange).toHaveBeenCalledWith(['Fhishing', 'Skiing', 'Dancing']);
   });
+
+  it('deserializes an Array to an Array', () => {
+    const array = ['a', 'b', 'c'];
+    const deserialized = ArrayType.deserialize(array);
+
+    expect(Array.isArray(deserialized)).toEqual(true);
+    expect(deserialized).toEqual(['a', 'b', 'c']);
+  });
+
+  it('deserializes an Object to an Array', () => {
+    const object = { 1: 'one', 0: 'zero', 2: 'two' };
+
+    const deserialized = ArrayType.deserialize(object);
+
+    expect(Array.isArray(deserialized)).toEqual(true);
+    expect(deserialized).toEqual(['zero', 'one', 'two']);
+  });
 });

addons/knobs/src/components/types/Array.js

@@ -47,6 +47,10 @@ ArrayType.propTypes = {
 };
 
 ArrayType.serialize = value => value;
-ArrayType.deserialize = value => value;
+ArrayType.deserialize = value => {
+  if (Array.isArray(value)) return value;
+
+  return Object.keys(value).reduce((array, key) => [...array, value[key]], []);
+};
 
 export default ArrayType;