LibJS: Implement Temporal.ZonedDateTime.prototype.round

Author: https://github.com/trflynn89
Commit: f2ab9e1aa9
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2577
Reviewed-by: https://github.com/shannonbooth ✅

Libraries/LibJS/Tests/builtins/Temporal/ZonedDateTime/ZonedDateTime.prototype.round.js

@@ -0,0 +1,94 @@
+describe("correct behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.ZonedDateTime.prototype.round).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        const zonedDateTime = new Temporal.ZonedDateTime(1111111111111n, "UTC");
+        expect(zonedDateTime.round({ smallestUnit: "second" }).epochNanoseconds).toBe(
+            1111000000000n
+        );
+        expect(
+            zonedDateTime.round({ smallestUnit: "second", roundingMode: "ceil" }).epochNanoseconds
+        ).toBe(1112000000000n);
+        expect(
+            zonedDateTime.round({
+                smallestUnit: "minute",
+                roundingIncrement: 30,
+                roundingMode: "floor",
+            }).epochNanoseconds
+        ).toBe(0n);
+        expect(
+            zonedDateTime.round({
+                smallestUnit: "minute",
+                roundingIncrement: 30,
+                roundingMode: "halfExpand",
+            }).epochNanoseconds
+        ).toBe(1800000000000n);
+    });
+
+    test("string argument is implicitly converted to options object", () => {
+        const zonedDateTime = new Temporal.ZonedDateTime(1111111111111n, "UTC");
+        expect(
+            zonedDateTime.round("second").equals(zonedDateTime.round({ smallestUnit: "second" }))
+        ).toBeTrue();
+    });
+});
+
+describe("errors", () => {
+    test("this value must be a Temporal.ZonedDateTime object", () => {
+        expect(() => {
+            Temporal.ZonedDateTime.prototype.round.call("foo");
+        }).toThrowWithMessage(TypeError, "Not an object of type Temporal.ZonedDateTime");
+    });
+
+    test("missing options object", () => {
+        const zonedDateTime = new Temporal.ZonedDateTime(1n, "UTC");
+        expect(() => {
+            zonedDateTime.round();
+        }).toThrowWithMessage(TypeError, "Required options object is missing or undefined");
+    });
+
+    test("invalid rounding mode", () => {
+        const zonedDateTime = new Temporal.ZonedDateTime(1n, "UTC");
+        expect(() => {
+            zonedDateTime.round({ smallestUnit: "second", roundingMode: "serenityOS" });
+        }).toThrowWithMessage(
+            RangeError,
+            "serenityOS is not a valid value for option roundingMode"
+        );
+    });
+
+    test("invalid smallest unit", () => {
+        const zonedDateTime = new Temporal.ZonedDateTime(1n, "UTC");
+        expect(() => {
+            zonedDateTime.round({ smallestUnit: "serenityOS" });
+        }).toThrowWithMessage(
+            RangeError,
+            "serenityOS is not a valid value for option smallestUnit"
+        );
+    });
+
+    test("increment may not be NaN", () => {
+        const zonedDateTime = new Temporal.ZonedDateTime(1n, "UTC");
+        expect(() => {
+            zonedDateTime.round({ smallestUnit: "second", roundingIncrement: NaN });
+        }).toThrowWithMessage(RangeError, "NaN is not a valid value for option roundingIncrement");
+    });
+
+    test("increment may smaller than 1 or larger than maximum", () => {
+        const zonedDateTime = new Temporal.ZonedDateTime(1n, "UTC");
+        expect(() => {
+            zonedDateTime.round({ smallestUnit: "second", roundingIncrement: -1 });
+        }).toThrowWithMessage(RangeError, "-1 is not a valid value for option roundingIncrement");
+        expect(() => {
+            zonedDateTime.round({ smallestUnit: "second", roundingIncrement: 0 });
+        }).toThrowWithMessage(RangeError, "0 is not a valid value for option roundingIncrement");
+        expect(() => {
+            zonedDateTime.round({ smallestUnit: "second", roundingIncrement: Infinity });
+        }).toThrowWithMessage(
+            RangeError,
+            "Infinity is not a valid value for option roundingIncrement"
+        );
+    });
+});