In 5-stretch-extend/format-time.js, tried edge cases and invalid inputs

Author: TzeMingHo

Sprint-2/5-stretch-extend/format-time.js

@@ -4,9 +4,38 @@
 
 function formatAs12HourClock(time) {
   const hours = Number(time.slice(0, 2));
+  const minutes = Number(time.slice(3));
+  if (isNaN(hours) || isNaN(minutes)) {
+    throw new Error("Invalid time");
+  }
+  if (hours < 0 || hours > 24 || minutes < 0 || minutes > 59) {
+    throw new Error("Invalid time");
+  }
+  if (time[2] !== ":") {
+    throw new Error("Invalid time");
+  }
+  if (time.length !== 5) {
+    throw new Error("Invalid time");
+  }
+
+  const minutesStr = String(minutes).padEnd(2, 0);
+
+  if (hours == 0) {
+    return `12:${minutesStr} am`;
+  }
+
+  if (hours == 12 && minutes >= 0) {
+    return `12:${minutesStr} pm`;
+  }
+
+  if (hours == 24) {
+    return `12:${minutesStr} am`;
+  }
+
   if (hours > 12) {
-    return `${hours - 12}:00 pm`;
+    return `${String(hours - 12).padStart(2, 0)}:${minutesStr} pm`;
   }
+
   return `${time} am`;
 }
 
@@ -23,3 +52,82 @@ console.assert(
   currentOutput2 === targetOutput2,
   `current output: ${currentOutput2}, target output: ${targetOutput2}`
 );
+
+const currentOutput3 = formatAs12HourClock("12:00");
+const targetOutput3 = "12:00 pm";
+console.assert(
+  currentOutput3 === targetOutput3,
+  `current output: ${currentOutput3}, target output: ${targetOutput3}`
+);
+
+const currentOutput4 = formatAs12HourClock("00:00");
+const targetOutput4 = "12:00 am";
+console.assert(
+  currentOutput4 === targetOutput4,
+  `current output: ${currentOutput4}, target output: ${targetOutput4}`
+);
+
+const currentOutput5 = formatAs12HourClock("15:30");
+const targetOutput5 = "03:30 pm";
+console.assert(
+  currentOutput5 === targetOutput5,
+  `current output: ${currentOutput5}, target output: ${targetOutput5}`
+);
+
+const currentOutput6 = formatAs12HourClock("11:15");
+const targetOutput6 = "11:15 am";
+console.assert(
+  currentOutput6 === targetOutput6,
+  `current output: ${currentOutput6}, target output: ${targetOutput6}`
+);
+
+const currentOutput7 = formatAs12HourClock("00:30");
+const targetOutput7 = "12:30 am";
+console.assert(
+  currentOutput7 === targetOutput7,
+  `current output: ${currentOutput7}, target output: ${targetOutput7}`
+);
+
+const currentOutput8 = formatAs12HourClock("12:45");
+const targetOutput8 = "12:45 pm";
+console.assert(
+  currentOutput8 === targetOutput8,
+  `current output: ${currentOutput8}, target output: ${targetOutput8}`
+);
+
+const currentOutput9 = formatAs12HourClock("24:00");
+const targetOutput9 = "12:00 am";
+console.assert(
+  currentOutput9 === targetOutput9,
+  `current output: ${currentOutput9}, target output: ${targetOutput9}`
+);
+
+try {
+  formatAs12HourClock("25:00");
+  console.assert(false, "Expected an error for invalid hours");
+} catch (e) {
+  console.assert(
+    e.message === "Invalid time",
+    `Unexpected error message: ${e.message}`
+  );
+}
+
+try {
+  formatAs12HourClock("10:60");
+  console.assert(false, "Expected an error for invalid minutes");
+} catch (e) {
+  console.assert(
+    e.message === "Invalid time",
+    `Unexpected error message: ${e.message}`
+  );
+}
+
+try {
+  formatAs12HourClock("ab:cd");
+  console.assert(false, "Expected an error for non-numeric input");
+} catch (e) {
+  console.assert(
+    e.message === "Invalid time",
+    `Unexpected error message: ${e.message}`
+  );
+}