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London | 26-Sep-ITP | Frumentius Tesfay | Sprint 1 | Format clock edge cases #1634

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London | 26-Sep-ITP | Frumentius Tesfay | Sprint 1 | Format clock edge cases #1634

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f5569ab
Fix midnight edge case
Frumentius-Rev Oct 2, 2026
6528243
fix noon edge case
Frumentius-Rev Oct 2, 2026
7f60bc9
Test 13:00 conversion
Frumentius-Rev Oct 2, 2026
e47b68e
Test 12:59 conversion
Frumentius-Rev Oct 2, 2026
e4d04ac
Test 23:59 conversion
Frumentius-Rev Oct 2, 2026
6fc1be1
Test 11:59 before noon
Frumentius-Rev Oct 2, 2026
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13 changes: 10 additions & 3 deletions format-clock-edge-cases/timeConverter.js
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Original file line number Diff line number Diff line change
@@ -1,11 +1,18 @@
function formatAs12HourClock(time) {

const hours = Number(time.slice(0, 2));

if (hours === 0) {
return `12:${time.slice(-2)} am`;
}

if (hours === 12) {
return `${time} pm`;
}

if (hours > 12) {
return `${hours - 12}:00 pm`;
return `${hours - 12}:${time.slice(-2)} pm`;
}
return `${time} am`;
}

export {formatAs12HourClock};
export { formatAs12HourClock };
31 changes: 26 additions & 5 deletions format-clock-edge-cases/timeConverter.test.js
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@cjyuan cjyuan Oct 4, 2026

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Could you check whether the expected return values specified in the tests use a consistent format?

When a function's return values are not consistently formatted, it can lead to unintended side effects. For examples:

  1. When the formatted strings are displayed, they may not align nicely:
01:00 am
1:00 pm
12:00 am
01:00 pm
02:00pm
  1. When the formatted strings are compared in a program, they may produce unexpected results:
  • "1:00 pm" < "11:00 pm" evaluates to false
  • "01:00 am" < "11:00 am" evaluates to true

For this reason, it would be better to ensure that the function always returns values in a consistent format.

Original file line number Diff line number Diff line change
@@ -1,11 +1,32 @@
import {formatAs12HourClock} from "./timeConverter.js";
import { formatAs12HourClock } from "./timeConverter.js";
import assert from "node:assert";
import test from "node:test";

test("correctly convert time after 12:00", function(){
assert.equal(formatAs12HourClock("23:00"), "11:00 pm");
test("correctly convert time after 12:00", function () {
assert.equal(formatAs12HourClock("23:00"), "11:00 pm");
});

test("can correctly convert morning time", function() {
assert.equal(formatAs12HourClock("08:00"), "08:00 am");
test("can correctly convert morning time", function () {
assert.equal(formatAs12HourClock("08:00"), "08:00 am");
});

test("can correctly convert midnight", () =>
assert.equal(formatAs12HourClock("00:00"), "12:00 am"));

test("converts noon 12:00", () =>
assert.equal(formatAs12HourClock("12:00"), "12:00 pm"));

test("converts 13:00", () =>
assert.equal(formatAs12HourClock("13:00"), "1:00 pm"));

test("converts 12:59", () =>
assert.equal(formatAs12HourClock("12:59"), "12:59 pm"));

test("converts 23:59 at night", () =>
assert.equal(formatAs12HourClock("23:59"), "11:59 pm"));

test("converts 00:59 after midnight", () =>
assert.equal(formatAs12HourClock("00:59"), "12:59 am"));

test("converts 11:59 before noon", () =>
assert.equal(formatAs12HourClock("11:59"), "11:59 am"));
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