Testing a function with expected and actual output

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Testing a function with expected and actual output

Name:
Date:
Class:
A

Quick Questions

Shade in the A or B circle for each question.

1. Which line compares the actual output of square(5) with the expected value?
A console.log("expected 25, got", square(5));
B console.log("square(5)");
2. square(5) logs "expected 25, got 10". What is the test result?
A Pass, because the function ran without an error
B Fail, because the actual value does not match the expected value
3. Which is the best way to choose the expected value for a test?
A Work it out by hand before you run the function
B Copy whatever the function prints and call it expected
4. Which set of inputs is the better test of a function that checks if a mark is a pass (50 or more)?
A 80, 81 and 82 only
B 49, 50 and 51 (boundary values) plus a normal value like 80
5. You fix a bug in your function. What should you do next?
A Run all the tests again, including the ones that passed before
B Only rerun the test that failed, because the others are fine
B

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left columnRight column
1console.log("expected 25, got", square(5)); Asquare is not called. Without brackets and an input like (5), it logs the function itself instead of the result.
2console.log("expected 0, got", square(0)); BThe actual result is typed in by hand, so the function is never called and the test proves nothing.
3Test a function with a normal input and log the expected value beside the actual output Cconsole.log("retest: expected 25, got", square(5));
4After fixing a bug, run the same test again to check the fix worked DCalls square with the input 5 and prints the actual result next to the expected value 25 so you can compare them.
5console.log("expected 25, got", square); Econsole.log("expected 36, got", square(6));
6console.log("expected 25, got 25"); FTests a boundary input: 0 is an edge case, and the expected result is written beside the actual result.
C

Definitions

console.log("expected 25, got", square(5))
D

Fill in the Blanks

Complete each line of code by filling in the missing parts.

1.
console.log("expected 25, got", ______(5));
2.
console.log("expected 25, got", square(_));
3.
console.log("expected 0, got", square(_));
4.
let actual = square(4); if (actual ___ 16) console.log("pass");
5.
function square(n) { return n _ n; } console.log("expected 25, got", square(5));
E

Spot the Error

Shade in the letter of the line that contains an error.

Question 1
A function sq(n) {
B return n * n;
C }
D console.log("want 25", sq);
Question 2
A function sq(n) {
B return n + n;
C }
D let got = sq(5);
E console.log("want 25", got);
Question 3
A function sq(n) {return n*n;}
B let got = sq(5);
C if (got = 25) {
D console.log("pass");
E }
Question 4
A function isAdult(age) {
B return age >= 18;
C }
D let got = isAdult(17);
E console.log("want true", got);
Question 5
A function sq(n) {return n*n;}
B let got = sq(6);
C console.log("want 36", get);

Answer Key

Testing a function with expected and actual output
Section A: Quick Questions
Q1
A — console.log("expected 25, got", square(5));
Q2
B — Fail, because the actual value does not match the expected value
Q3
A — Work it out by hand before you run the function
Q4
B — 49, 50 and 51 (boundary values) plus a normal value like 80
Q5
A — Run all the tests again, including the ones that passed before
Section B: Match the Pairs
Q1
console.log("expected 25, got", square(5)); → Calls square with the input 5 and prints the actual result next to the expected value 25 so you can compare them.
Q2
console.log("expected 0, got", square(0)); → Tests a boundary input: 0 is an edge case, and the expected result is written beside the actual result.
Q3
Test a function with a normal input and log the expected value beside the actual output → console.log("expected 36, got", square(6));
Q4
After fixing a bug, run the same test again to check the fix worked → console.log("retest: expected 25, got", square(5));
Q5
console.log("expected 25, got", square); → square is not called. Without brackets and an input like (5), it logs the function itself instead of the result.
Q6
console.log("expected 25, got 25"); → The actual result is typed in by hand, so the function is never called and the test proves nothing.
Section C: Definitions
Q1
console.log("expected 25, got", square(5)) — Test a function by calling it with chosen inputs, logging the actual result next to the expected value, then recording pass or fail. Retest after any fix.
Section D: Fill in the Blanks
Q1
console.log("expected 25, got", square(5));
Q2
console.log("expected 25, got", square(5));
Q3
console.log("expected 0, got", square(0));
Q4
let actual = square(4); if (actual === 16) console.log("pass");
Q5
function square(n) { return n * n; } console.log("expected 25, got", square(5));
Section E: Spot the Error
Q1
D — sq has no brackets or input, so the function is not called. The test prints the function itself, not the actual result. It should be sq(5).
Q2
B — Squaring means multiplying n by itself. With n + n, sq(5) gives 10, so the test would show 10 next to the expected 25 and fail. It should be return n * n;
Q3
C — A single = assigns 25 to got instead of comparing, so the test always 'passes'. Use === to compare the actual and expected values: if (got === 25) {
Q4
D — The test expects true for the boundary input 18. Calling isAdult(17) returns false, so the test does not check the boundary it claims to. It should be isAdult(18).
Q5
C — The variable is called got, not get. Using get causes a ReferenceError, so no actual value is shown. It should be console.log("want 36", got);