Fakes

src/app/doubles/OtherUtils.ts

@@ -6,7 +6,17 @@ export type stringInfo = {
     extraInfo: Object | undefined
 }
 
+type LoggerServiceCallBack = (arg: string) => void;
+
 export function calculateComplexity(stringInfo: stringInfo){
     return Object.keys(stringInfo.extraInfo).length * stringInfo.length
 }
 
+export function toUpperCaseWithCb(arg: string, callBack:LoggerServiceCallBack){
+    if(!arg) {
+        callBack('Invalid argument!');
+        return;
+    }
+    callBack(`called function with ${arg}`)
+    return arg.toUpperCase();
+}

src/test/doubles/OtherUtils.test.ts

@@ -0,0 +1,30 @@
+import { calculateComplexity, toUpperCaseWithCb } from "../../app/doubles/OtherUtils"
+
+
+describe('OtherUtils test suite', ()=>{
+
+    it('ToUpperCase - calls callback for invalid argument', ()=>{
+        const actual = toUpperCaseWithCb('', ()=>{});
+        expect(actual).toBeUndefined();
+    })
+
+    it('ToUpperCase - calls callback for valid argument', ()=>{
+        const actual = toUpperCaseWithCb('abc', ()=>{});
+        expect(actual).toBe('ABC');
+    })
+
+
+
+    it('Calculates complexity', ()=>{
+        const someInfo = {
+            length: 5,
+            extraInfo: {
+                field1: 'someInfo',
+                field2: 'someOtherInfo'
+            }
+        }
+
+        const actual = calculateComplexity(someInfo as any);
+        expect(actual).toBe(10);
+    })
+})