Add UInt .isMax() (#1791)

* Add UInt .isMax()

* Filter lockedBlance by max

packages/types/src/codec/AbstractInt.ts

@@ -111,6 +111,15 @@ export default abstract class AbstractInt extends BN implements Codec {
     );
   }
 
+  /**
+   * @description True if this value is the max of the type
+   */
+  public isMax (): boolean {
+    const u8a = this.toU8a().filter((byte): boolean => byte === 0xff);
+
+    return u8a.length === (this._bitLength / 8);
+  }
+
   /**
    * @description Returns the BN representation of the number. (Compatibility)
    */

packages/types/src/codec/UInt.spec.ts

@@ -70,4 +70,17 @@ describe('UInt', (): void => {
       expect(test.eq('0x3039')).toBe(true);
     });
   });
+
+  describe('isMax()', (): void => {
+    it('is false where not full', (): void => {
+      expect(new UInt(registry, '0x1234', 32).isMax()).toEqual(false);
+      expect(new UInt(registry, '0xffffff', 32).isMax()).toEqual(false);
+      expect(new UInt(registry, '0x12345678', 32).isMax()).toEqual(false);
+      expect(new UInt(registry, '0xfffffff0', 32).isMax()).toEqual(false);
+    });
+
+    it('is true when full', (): void => {
+      expect(new UInt(registry, '0xffffffff', 32).isMax()).toEqual(true);
+    });
+  });
 });