LibJS: Implement Temporal.Instant.fromEpochMilliseconds()

Author: https://github.com/linusg Commit: 66ff772254 Pull-request: https://github.com/SerenityOS/serenity/pull/8580
2025-08-03 14:50:18 +00:00 · 2021-07-09 12:00:31 +01:00 · 2021-07-09 12:00:31 +01:00 · 66ff772254 · 2024-07-18 10:00:33 +09:00
commit 66ff772254
parent 2401e45720
4 changed files with 81 additions and 0 deletions
--- a/Userland/Libraries/LibJS/Tests/builtins/Temporal/Instant/Instant.fromEpochMilliseconds.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Temporal/Instant/Instant.fromEpochMilliseconds.js
@ -0,0 +1,52 @@
+describe("correct behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.Instant.fromEpochMilliseconds).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        expect(Temporal.Instant.fromEpochMilliseconds(0).epochMilliseconds).toBe(0);
+        expect(Temporal.Instant.fromEpochMilliseconds(1).epochMilliseconds).toBe(1);
+        expect(Temporal.Instant.fromEpochMilliseconds(999_999_999).epochMilliseconds).toBe(
+            999_999_999
+        );
+        expect(
+            Temporal.Instant.fromEpochMilliseconds(8_640_000_000_000_000).epochMilliseconds
+        ).toBe(8_640_000_000_000_000);
+
+        expect(Temporal.Instant.fromEpochMilliseconds(-0).epochMilliseconds).toBe(0);
+        expect(Temporal.Instant.fromEpochMilliseconds(-1).epochMilliseconds).toBe(-1);
+        expect(Temporal.Instant.fromEpochMilliseconds(-999_999_999).epochMilliseconds).toBe(
+            -999_999_999
+        );
+        expect(
+            Temporal.Instant.fromEpochMilliseconds(-8_640_000_000_000_000).epochMilliseconds
+        ).toBe(-8_640_000_000_000_000);
+    });
+});
+
+test("errors", () => {
+    test("argument must be coercible to BigInt", () => {
+        expect(() => {
+            Temporal.Instant.fromEpochMilliseconds(1.23);
+        }).toThrowWithMessage(RangeError, "Cannot convert non-integral number to BigInt");
+        // NOTE: ToNumber is called on the argument first, so this is effectively NaN.
+        expect(() => {
+            Temporal.Instant.fromEpochMilliseconds("foo");
+        }).toThrowWithMessage(RangeError, "Cannot convert non-integral number to BigInt");
+    });
+
+    test("out-of-range epoch milliseconds value", () => {
+        expect(() => {
+            Temporal.Instant.fromEpochMilliseconds(8_640_000_000_000_001);
+        }).toThrowWithMessage(
+            RangeError,
+            "Invalid epoch nanoseconds value, must be in range -86400 * 10^17 to 86400 * 10^17"
+        );
+        expect(() => {
+            Temporal.Instant.fromEpochMilliseconds(-8_640_000_000_000_001);
+        }).toThrowWithMessage(
+            RangeError,
+            "Invalid epoch nanoseconds value, must be in range -86400 * 10^17 to 86400 * 10^17"
+        );
+    });
+});