Cleanup Text from U8a (wrapper class) (#1642)

* Cleanup Text from U8a (wrapper class)

* U8a test

packages/types/src/primitive/Text.spec.ts

@@ -19,7 +19,7 @@ describe('Text', (): void => {
     testDecode('string', 'foo', 'foo');
     testDecode('Text', new Text(registry, 'foo'), 'foo');
     testDecode('Uint8Array', Uint8Array.from([12, 102, 111, 111]), 'foo');
-    testDecode('U8a', new U8a(registry, Uint8Array.from([12, 102, 111, 111])), 'foo');
+    testDecode('U8a', new U8a(registry, Uint8Array.from([102, 111, 111])), 'foo'); // no length
     testDecode('object with `toString()`', { toString (): string { return 'foo'; } }, 'foo');
     testDecode('hex input value', new Text(registry, '0x12345678'), '0x12345678', 'toHex');
   });

packages/types/src/primitive/Text.ts

@@ -9,6 +9,7 @@ import { blake2AsU8a } from '@polkadot/util-crypto';
 
 import { createType } from '../codec/create';
 import Compact from '../codec/Compact';
+import U8a from '../codec/U8a';
 
 /**
  * @name Text
@@ -37,6 +38,12 @@ export default class Text extends String implements Codec {
         return '';
       }
 
+      // for U8a, the internal buffer does not have an internal length
+      // (the same applies in e.g. Bytes, where length is added at encoding-time)
+      if (value instanceof U8a) {
+        return u8aToString(value);
+      }
+
       const [offset, length] = Compact.decodeU8a(value);
       const total = offset + length.toNumber();