update test wording for undefined fn returns (#36804)

* update test wording for undefined fn returns, bring code out of after test section and check that the function does what it says it does (rather than just checking the result), update seed, example, and solution

curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.english.md

@@ -16,7 +16,7 @@ var sum = 0;
 function addSum(num) {
   sum = sum + num;
 }
-var returnedValue = addSum(3); // sum will be modified but returned value is undefined
+addSum(3); // sum will be modified but returned value is undefined
 ```
 
 <code>addSum</code> is a function without a <code>return</code> statement. The function will change the global <code>sum</code> variable but the returned value of the function is <code>undefined</code>.
@@ -34,12 +34,12 @@ Create a function <code>addFive</code> without any arguments. This function adds
 tests:
   - text: <code>addFive</code> should be a function
     testString: assert(typeof addFive === 'function');
-  - text: <code>sum</code> should be equal to 8
+  - text: Once both functions have ran, the <code>sum</code> should be equal to 8
     testString: assert(sum === 8);
   - text: Returned value from <code>addFive</code> should be <code>undefined</code>
     testString: assert(addFive() === undefined);
-  - text: Inside of your functions, add 5 to the <code>sum</code> variable
-    testString: assert(code.match(/(sum\s*\=\s*sum\s*\+\s*5)|(sum\s*\+\=\s*5)/g).length === 1);
+  - text: Inside the <code>addFive</code> function, add <code>5</code> to the <code>sum</code> variable
+    testString: assert(addFive.toString().replace(/\s/g, '').match(/sum=sum\+5|sum\+=5/));
 
 ```
 
@@ -59,37 +59,34 @@ function addThree() {
 
 // Only change code below this line
 
-
-
 // Only change code above this line
-var returnedValue = addFive();
-```
-
-</div>
-
-
-### After Test
-<div id='js-teardown'>
-
-```js
-var sum = 0;
-function addThree() {sum = sum + 3;}
 addThree();
 addFive();
 ```
 
 </div>
 
-</section>
 
 ## Solution
 <section id='solution'>
 
 
 ```js
-function addFive() {
- sum = sum + 5;
+// Example
+var sum = 0;
+function addThree() {
+  sum = sum + 3;
 }
+
+// Only change code below this line
+
+function addFive() {
+  sum = sum + 5;
+}
+
+// Only change code above this line
+addThree();
+addFive();
 ```
 
 </section>