London | ITP-Jan-26 | Mohsen Zamani | Sprint 3 | stretch by mohsenzamanist · Pull Request #939 · CodeYourFuture/Module-Structuring-and-Testing-Data

mohsenzamanist · 2026-02-07T19:19:40Z

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I have titled my PR with Region | Cohort | FirstName LastName | Sprint | Assignment Title
My changes meet the requirements of the task
I have tested my changes
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Comelete exercises in directory called 4-stretch

Questions

cjyuan · 2026-02-17T01:11:11Z

Sprint-3/4-stretch/card-validator.js

+    !cardNumArray.every(
+      (num) => num.charCodeAt(0) >= 48 && num.charCodeAt(0) <= 57
+    )


Note: We could also check if num is a digit as num >= '0' && num <= '9'.

cjyuan · 2026-02-17T01:15:39Z

Sprint-3/4-stretch/card-validator.js

+  const count = cardNumArray.reduce((acc, curr) => {
+    acc[curr] = acc[curr] ? acc[curr] + 1 : 1;
+    return acc;
+  }, {});
+  if (Object.keys(count).length < 2) return false;


This works.
Challenge: Implement a simpler and more efficient way to check distinct digit count with Set.

cjyuan · 2026-02-17T01:21:48Z

Sprint-3/4-stretch/password-validator.js

@@ -1,6 +1,12 @@
+const previousPasswords = ["5B43n21"];
 function passwordValidator(password) {


If we design the function as

function passwordValidator(password, previousPasswords=[]) { ... }

we could let the caller specify what the previous passwords are.

cjyuan · 2026-02-17T01:24:08Z

Sprint-3/4-stretch/password-validator.js

@@ -1,6 +1,12 @@
+const previousPasswords = ["5B43n21"];


An invalid password is not a good candidate for a previous password.

cjyuan · 2026-02-17T01:28:15Z

Sprint-3/4-stretch/password-validator.test.js

-}
-);
+  // Arrange
+  const password = "A1b2";


The function can return false for multiple reasons.
To test a specific reason, choose an input that satisfies all other conditions except the one you're targeting. This way, if the function returns false, you can confidently attribute it to that specific condition.

For example, the function might return false for "A1b2" not only because it is fewer than 5 characters, but also because it lacks a special letter.
As a result, we can't be certain that the function correctly handles the case of passwords shorter than 5 characters, since multiple conditions are being violated simultaneously.

cjyuan · 2026-02-17T01:38:29Z

Sprint-3/4-stretch/password-validator.test.js

+test("password contains at least one uppercase English letter", () => {
+  // Arrange
+  const password = "1a2345";
+  // Act
+  const result = isValidPassword(password);
+  // Assert
+  expect(result).toEqual(false);
+});
+
+test("password contains at least one uppercase English letter", () => {
+  // Arrange
+  const password = "1B2345";
+  // Act
+  const result = isValidPassword(password);
+  // Assert
+  expect(result).toEqual(false);
+});


These two tests have the same description but they are testing two different things.

cjyuan · 2026-02-17T01:41:23Z

Sprint-3/4-stretch/password-validator.test.js

Could you make the test descriptions more detailed and descriptive? That way, if a test fails, the person implementing the function can quickly understand what went wrong and why.

Right now, for example, "password contains at least one number (0-9)" does not quite indicate what the test is testing. (Did you mean to say "not containing")

cjyuan

Did you run Jest test after you made the changes? It seems one of the tests in password-validator.test.js has a bug and will fail.

cjyuan · 2026-02-17T12:08:44Z

Sprint-3/4-stretch/card-validator.js

+  if (cardNumArray.length !== 16) return false;
+
+  // checks if all digits are numbers
+  if (!cardNumArray.every((num) => num >= 0 && num <= 9)) return false;


if (!cardNumArray.every((num) => num >= 0 && num <= 9)) return false; if (!cardNumArray.every((num) => num >= '0' && num <= '9')) return false;

Both produce the same result, the latter expression is more a commonly used.

Performance wise, while it is hardly noticeable, the former expression is less efficient
because it requires the number to be converted to string first before the comparison takes place.

cjyuan · 2026-02-17T12:14:27Z

Sprint-3/4-stretch/password-validator.test.js

+  expect(result).toEqual(false);
+});
+
+test("should return false if password has no numbers(0-9)", () => {


Could shorten the description by using the term digit.

mohsenzamanist · 2026-02-17T15:43:40Z

I ran jest and password-validator.test.js works perfectly, all the tests passed.

cjyuan

Great work!

You have all the info I intend to pass to you. So I will go ahead and mark this PR as complete first.

cjyuan · 2026-02-17T16:24:05Z

Sprint-3/4-stretch/password-validator.test.js

+  // Arrange
+  const password = "5B43n21!";
+  // Act
+  const result = isValidPassword(password, "5B43n21!");


I expected this test to fail because the second parameter isn't an array of strings.

I didn't realise string also has a method .includes() and your function manages to pass this test.

However, other implementations that expect the second parameter to be an array may fail this test unexpectedly.

Appreciate all the comments.
I missed that it should be an array and it's surprising the code is working.
But if function explicitly checks for an array then it'll fail, so I'll add the check to the function and change the test as well.
Thanks.

Complete sprint-3-stretch

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		@@ -1,6 +1,12 @@
		const previousPasswords = ["5B43n21"];
		function passwordValidator(password) {

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mohsenzamanist commented Feb 7, 2026

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