Option instantiates from Option (#465)

packages/types/src/codec/Option.spec.js

@@ -27,6 +27,12 @@ describe('Option', () => {
     expect(new Option(Text, 'test').isNone).toBe(false);
   });
 
+  it('converts an option to an option', () => {
+    expect(
+      new Option(Text, new Option(Text, 'hello')).toString()
+    ).toEqual('hello');
+  });
+
   testDecode('string (with)', 'foo', 'foo');
   testDecode('string (without)', undefined, '');
   testDecode('Uint8Array (with)', Uint8Array.from([1, 12, 102, 111, 111]), 'foo');

packages/types/src/codec/Option.ts

@@ -25,11 +25,11 @@ export default class Option<T extends Codec> extends Base<T> implements Codec {
 
   static decodeOption<O> (Type: Constructor, value?: any): Codec {
     if (isU8a(value)) {
-      if (value[0] === 0) {
-        return new Null();
-      }
-
-      return new Type(value.subarray(1));
+      return value[0] === 0
+        ? new Null()
+        : new Type(value.subarray(1));
+    } else if (value instanceof Option) {
+      return Option.decodeOption(Type, value.value);
     }
 
     return isNull(value) || isUndefined(value) || value instanceof Null