LibJS: Adjust ISO8601 representation for years between 1 BCE and 999 CE

This is a normative change in the Temporal spec.

See: https://github.com/tc39/proposal-temporal/commit/39eeecd

3 files changed, 17 insertions, 10 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp
index c567ce0783..85d62dc2cd 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp
@@ -499,13 +499,14 @@ String pad_iso_year(i32 y)
 {
     // 1. Assert: y is an integer.
 
-    // 2. If y > 999 and y ≤ 9999, then
-    if (y > 999 && y <= 9999) {
-        // a. Return y formatted as a four-digit decimal number.
-        return String::number(y);
+    // 2. If y ≥ 0 and y ≤ 9999, then
+    if (y >= 0 && y <= 9999) {
+        // a. Return y formatted as a four-digit decimal number, padded to the left with zeroes as necessary.
+        return String::formatted("{:04}", y);
     }
-    // 3. If y ≥ 0, let yearSign be "+"; otherwise, let yearSign be "-".
-    auto year_sign = y >= 0 ? '+' : '-';
+
+    // 3. If y > 0, let yearSign be "+"; otherwise, let yearSign be "-".
+    auto year_sign = y > 0 ? '+' : '-';
 
     // 4. Let year be abs(y), formatted as a six-digit decimal number, padded to the left with zeroes as necessary.
     // 5. Return the string-concatenation of yearSign and year.
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainDate/PlainDate.prototype.toString.js b/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainDate/PlainDate.prototype.toString.js
index 0722a55340..3faad7c0a8 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainDate/PlainDate.prototype.toString.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainDate/PlainDate.prototype.toString.js
@@ -19,10 +19,13 @@ describe("correct behavior", () => {
         expect(plainDate.toString({ calendarName: "never" })).toBe("2021-07-06");
 
         plainDate = new Temporal.PlainDate(0, 1, 1);
-        expect(plainDate.toString()).toBe("+000000-01-01");
+        expect(plainDate.toString()).toBe("0000-01-01");
 
         plainDate = new Temporal.PlainDate(999, 1, 1);
-        expect(plainDate.toString()).toBe("+000999-01-01");
+        expect(plainDate.toString()).toBe("0999-01-01");
+
+        plainDate = new Temporal.PlainDate(9999, 1, 1);
+        expect(plainDate.toString()).toBe("9999-01-01");
 
         plainDate = new Temporal.PlainDate(12345, 1, 1);
         expect(plainDate.toString()).toBe("+012345-01-01");
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainYearMonth/PlainYearMonth.prototype.toString.js b/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainYearMonth/PlainYearMonth.prototype.toString.js
index 2be37729d9..487cedda4d 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainYearMonth/PlainYearMonth.prototype.toString.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainYearMonth/PlainYearMonth.prototype.toString.js
@@ -21,10 +21,13 @@ describe("correct behavior", () => {
         expect(plainYearMonth.toString({ calendarName: "never" })).toBe("2021-07-06");
 
         plainYearMonth = new Temporal.PlainYearMonth(0, 1);
-        expect(plainYearMonth.toString()).toBe("+000000-01");
+        expect(plainYearMonth.toString()).toBe("0000-01");
 
         plainYearMonth = new Temporal.PlainYearMonth(999, 1);
-        expect(plainYearMonth.toString()).toBe("+000999-01");
+        expect(plainYearMonth.toString()).toBe("0999-01");
+
+        plainYearMonth = new Temporal.PlainYearMonth(9999, 1);
+        expect(plainYearMonth.toString()).toBe("9999-01");
 
         plainYearMonth = new Temporal.PlainYearMonth(12345, 1);
         expect(plainYearMonth.toString()).toBe("+012345-01");