clarify Wh test

Author: af-hm

test/unit-tests/type/unit/Unit.test.js

@@ -1089,13 +1089,13 @@ describe('Unit', function () {
     })
 
     it('should be able to combine W and h into Wh', function () {
-      // by default, this converts to J, due to the default unit system
+      // by default, this converts to J, due to the default unit system using J for ENERGY
       const n1 = 2
       const n2 = 3
       const unit1 = new Unit(n1, 'W')
       const unit2 = new Unit(n2, 'h')
-      const unitM = unit1.multiply(unit2).to('Wh')
-      assert.strictEqual(unitM.units[0].unit.name, 'Wh')
+      const unitM = unit1.multiply(unit2).simplify()
+      assert.strictEqual(unitM.units[0].unit.name, 'J')
       assert.strictEqual(unitM.value, n1 * n2 * 3600)
     })