Allow ExtrinsicEra to construct via instance (#1136)

packages/types/src/type/ExtrinsicEra.spec.ts

@@ -19,6 +19,13 @@ describe('ExtrinsicEra', (): void => {
     expect(extrinsicEra.asMortalEra.phase.toNumber()).toEqual(20000);
   });
 
+  it('decoded from an existing ExtrinsicEra', (): void => {
+    const extrinsicEra = new ExtrinsicEra(new ExtrinsicEra(new Uint8Array([78, 156])));
+
+    expect(extrinsicEra.asMortalEra.period.toNumber()).toEqual(32768);
+    expect(extrinsicEra.asMortalEra.phase.toNumber()).toEqual(20000);
+  });
+
   it('encode an Extrinsic Era from Object with blocknumber & period as mortal instance', (): void => {
     const extrinsicEra = new ExtrinsicEra({ current: 1400, period: 200 });
 

packages/types/src/type/ExtrinsicEra.ts

@@ -192,8 +192,10 @@ export default class ExtrinsicEra extends Enum implements IExtrinsicEra {
   }
 
   // eslint-disable-next-line @typescript-eslint/ban-types
-  private static decodeExtrinsicEra (value: MortalMethod | MortalEnumDef | ImmortalEnumDef | Uint8Array | string = new Uint8Array()): Uint8Array | Object | undefined {
-    if (isHex(value)) {
+  private static decodeExtrinsicEra (value: IExtrinsicEra | MortalMethod | MortalEnumDef | ImmortalEnumDef | Uint8Array | string = new Uint8Array()): Uint8Array | Object | undefined {
+    if (value instanceof ExtrinsicEra) {
+      return ExtrinsicEra.decodeExtrinsicEra(value.toU8a());
+    } else if (isHex(value)) {
       return ExtrinsicEra.decodeExtrinsicEra(hexToU8a(value));
     } else if (isU8a(value)) {
       if (!value.length || value[0] === 0) {
@@ -263,10 +265,8 @@ export default class ExtrinsicEra extends Enum implements IExtrinsicEra {
    * @param isBare true when the value has none of the type-specific prefixes (internal)
    */
   public toU8a (isBare?: boolean): Uint8Array {
-    if (this.index === 0) {
-      return this.asImmortalEra.toU8a(isBare);
-    } else {
-      return this.asMortalEra.toU8a(isBare);
-    }
+    return this.isMortalEra
+      ? this.asMortalEra.toU8a(isBare)
+      : this.asImmortalEra.toU8a(isBare);
   }
 }