add docs, rename classes for clarity

src/app/shared/testing/utils.ts

@@ -31,6 +31,14 @@ export const createTestComponent = <T>(html: string, type: { new(...args: any[])
   return fixture as ComponentFixture<T>;
 };
 
+/**
+ * Allows you to spy on a read only property
+ *
+ * @param obj
+ *    The object to spy on
+ * @param prop
+ *    The property to spy on
+ */
 export function spyOnOperator(obj: any, prop: string): any {
   const oldProp = obj[prop];
   Object.defineProperty(obj, prop, {