LibJS: Add some more tests, mostly around leap years

2 files changed, 23 insertions, 0 deletions

diff --git a/Libraries/LibJS/Tests/builtins/Date/Date.UTC.js b/Libraries/LibJS/Tests/builtins/Date/Date.UTC.js
index f1194dd495..d5c8082729 100644
--- a/Libraries/LibJS/Tests/builtins/Date/Date.UTC.js
+++ b/Libraries/LibJS/Tests/builtins/Date/Date.UTC.js
@@ -26,6 +26,10 @@ test("basic functionality", () => {
     expect(Date.UTC(20000, 0)).toBe(568971820800000);
 });
 
+test("leap year", () => {
+    expect(Date.UTC(2020, 2, 1)).toBe(1583020800000);
+});
+
 test("out of range", () => {
     expect(Date.UTC(2020, -20)).toBe(1525132800000);
     expect(Date.UTC(2020, 20)).toBe(1630454400000);
diff --git a/Libraries/LibJS/Tests/builtins/Date/Date.prototype.getUTCMonth.js b/Libraries/LibJS/Tests/builtins/Date/Date.prototype.getUTCMonth.js
index 8b031497de..ed6ed64d97 100644
--- a/Libraries/LibJS/Tests/builtins/Date/Date.prototype.getUTCMonth.js
+++ b/Libraries/LibJS/Tests/builtins/Date/Date.prototype.getUTCMonth.js
@@ -4,4 +4,23 @@ test("basic functionality", () => {
     expect(d.getUTCMonth()).not.toBeNaN();
     expect(d.getUTCMonth()).toBeGreaterThanOrEqual(0);
     expect(d.getUTCMonth()).toBeLessThanOrEqual(11);
+
+    expect(new Date(Date.UTC(2020, 11)).getUTCMonth()).toBe(11);
+});
+
+test("leap years", () => {
+    expect(new Date(Date.UTC(2019, 1, 29)).getUTCDate()).toBe(1);
+    expect(new Date(Date.UTC(2019, 1, 29)).getUTCMonth()).toBe(2);
+    expect(new Date(Date.UTC(2100, 1, 29)).getUTCDate()).toBe(1);
+    expect(new Date(Date.UTC(2100, 1, 29)).getUTCMonth()).toBe(2);
+
+    expect(new Date(Date.UTC(2000, 1, 29)).getUTCDate()).toBe(29);
+    expect(new Date(Date.UTC(2000, 1, 29)).getUTCMonth()).toBe(1);
+    expect(new Date(Date.UTC(2020, 1, 29)).getUTCDate()).toBe(29);
+    expect(new Date(Date.UTC(2020, 1, 29)).getUTCMonth()).toBe(1);
+
+    expect(new Date(Date.UTC(2019, 2, 1)).getUTCDate()).toBe(1);
+    expect(new Date(Date.UTC(2019, 2, 1)).getUTCMonth()).toBe(2);
+    expect(new Date(Date.UTC(2020, 2, 1)).getUTCDate()).toBe(1);
+    expect(new Date(Date.UTC(2020, 2, 1)).getUTCMonth()).toBe(2);
 });