LibJS: Implement Temporal.Instant.fromEpochMicroseconds()

Author: https://github.com/linusg
Commit: https://github.com/SerenityOS/serenity/commit/5872357b56e
Pull-request: https://github.com/SerenityOS/serenity/pull/8580

Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h

@@ -143,6 +143,7 @@ namespace JS {
     P(fromCharCode)                          \
     P(fromCodePoint)                         \
     P(fromEntries)                           \
+    P(fromEpochMicroseconds)                 \
     P(fromEpochMilliseconds)                 \
     P(fromEpochSeconds)                      \
     P(fround)                                \

Userland/Libraries/LibJS/Runtime/Temporal/InstantConstructor.cpp

@@ -29,6 +29,7 @@ void InstantConstructor::initialize(GlobalObject& global_object)
     u8 attr = Attribute::Writable | Attribute::Configurable;
     define_native_function(vm.names.fromEpochSeconds, from_epoch_seconds, 1, attr);
     define_native_function(vm.names.fromEpochMilliseconds, from_epoch_milliseconds, 1, attr);
+    define_native_function(vm.names.fromEpochMicroseconds, from_epoch_microseconds, 1, attr);
 
     define_direct_property(vm.names.length, Value(1), Attribute::Configurable);
 }
@@ -117,4 +118,25 @@ JS_DEFINE_NATIVE_FUNCTION(InstantConstructor::from_epoch_milliseconds)
     return create_temporal_instant(global_object, *epoch_nanoseconds);
 }
 
+// 8.2.5 Temporal.Instant.fromEpochMicroseconds ( epochMicroseconds )
+JS_DEFINE_NATIVE_FUNCTION(InstantConstructor::from_epoch_microseconds)
+{
+    // 1. Set epochMicroseconds to ? ToBigInt(epochMicroseconds).
+    auto* epoch_microseconds = vm.argument(0).to_bigint(global_object);
+    if (vm.exception())
+        return {};
+
+    // 2. Let epochNanoseconds be epochMicroseconds × 1000ℤ.
+    auto* epoch_nanoseconds = js_bigint(vm.heap(), epoch_microseconds->big_integer().multiplied_by(Crypto::UnsignedBigInteger { 1'000 }));
+
+    // 3. If ! IsValidEpochNanoseconds(epochNanoseconds) is false, throw a RangeError exception.
+    if (!is_valid_epoch_nanoseconds(*epoch_nanoseconds)) {
+        vm.throw_exception<RangeError>(global_object, ErrorType::TemporalInvalidEpochNanoseconds);
+        return {};
+    }
+
+    // 4. Return ? CreateTemporalInstant(epochNanoseconds).
+    return create_temporal_instant(global_object, *epoch_nanoseconds);
+}
+
 }

Userland/Libraries/LibJS/Runtime/Temporal/InstantConstructor.h

@@ -26,6 +26,7 @@ private:
 
     JS_DECLARE_NATIVE_FUNCTION(from_epoch_seconds);
     JS_DECLARE_NATIVE_FUNCTION(from_epoch_milliseconds);
+    JS_DECLARE_NATIVE_FUNCTION(from_epoch_microseconds);
 };
 
 }

Userland/Libraries/LibJS/Tests/builtins/Temporal/Instant/Instant.fromEpochMicroseconds.js

@@ -0,0 +1,51 @@
+describe("correct behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.Instant.fromEpochMicroseconds).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        expect(Temporal.Instant.fromEpochMicroseconds(0n).epochMicroseconds).toBe(0n);
+        expect(Temporal.Instant.fromEpochMicroseconds(1n).epochMicroseconds).toBe(1n);
+        expect(Temporal.Instant.fromEpochMicroseconds(999_999_999n).epochMicroseconds).toBe(
+            999_999_999n
+        );
+        expect(
+            Temporal.Instant.fromEpochMicroseconds(8_640_000_000_000_000_000n).epochMicroseconds
+        ).toBe(8_640_000_000_000_000_000n);
+
+        expect(Temporal.Instant.fromEpochMicroseconds(-0n).epochMicroseconds).toBe(0n);
+        expect(Temporal.Instant.fromEpochMicroseconds(-1n).epochMicroseconds).toBe(-1n);
+        expect(Temporal.Instant.fromEpochMicroseconds(-999_999_999n).epochMicroseconds).toBe(
+            -999_999_999n
+        );
+        expect(
+            Temporal.Instant.fromEpochMicroseconds(-8_640_000_000_000_000_000n).epochMicroseconds
+        ).toBe(-8_640_000_000_000_000_000n);
+    });
+});
+
+test("errors", () => {
+    test("argument must be coercible to BigInt", () => {
+        expect(() => {
+            Temporal.Instant.fromEpochMicroseconds(123);
+        }).toThrowWithMessage(TypeError, "Cannot convert number to BigInt");
+        expect(() => {
+            Temporal.Instant.fromEpochMicroseconds("foo");
+        }).toThrowWithMessage(SyntaxError, "Invalid value for BigInt: foo");
+    });
+
+    test("out-of-range epoch microseconds value", () => {
+        expect(() => {
+            Temporal.Instant.fromEpochMicroseconds(8_640_000_000_000_000_001n);
+        }).toThrowWithMessage(
+            RangeError,
+            "Invalid epoch nanoseconds value, must be in range -86400 * 10^17 to 86400 * 10^17"
+        );
+        expect(() => {
+            Temporal.Instant.fromEpochMicroseconds(-8_640_000_000_000_000_001n);
+        }).toThrowWithMessage(
+            RangeError,
+            "Invalid epoch nanoseconds value, must be in range -86400 * 10^17 to 86400 * 10^17"
+        );
+    });
+});