1 files changed, 181 insertions, 0 deletions
diff --git a/js/src/jsapi-tests/testFractionToDouble.cpp b/js/src/jsapi-tests/testFractionToDouble.cpp
new file mode 100644
index 0000000000..c3e6842863
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+++ b/js/src/jsapi-tests/testFractionToDouble.cpp
@@ -0,0 +1,181 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifdef JS_HAS_TEMPORAL_API
+
+#  include <cmath>
+#  include <stdint.h>
+
+#  include "builtin/temporal/Int128.h"
+#  include "builtin/temporal/Temporal.h"
+#  include "jsapi-tests/tests.h"
+
+using namespace js::temporal;
+
+// Simple test using numerators and denominators where the result can be
+// computed through standard double division.
+BEGIN_TEST(testFraction_simple) {
+  int64_t numerators[] = {
+      0, 1, 2, 10, 100, INT32_MIN, INT32_MAX,
+  };
+
+  int64_t denominators[] = {
+      1, 2, 3, 10, 100, 1000,
+  };
+
+  for (auto numerator : numerators) {
+    for (auto denominator : denominators) {
+      double result = double(numerator) / double(denominator);
+
+      CHECK_EQUAL(FractionToDouble(numerator, denominator), result);
+      CHECK_EQUAL(FractionToDouble(Int128{numerator}, Int128{denominator}),
+                  result);
+
+      CHECK_EQUAL(FractionToDouble(-numerator, denominator),
+                  std::copysign(result, -numerator));
+      CHECK_EQUAL(FractionToDouble(-Int128{numerator}, Int128{denominator}),
+                  std::copysign(result, -numerator));
+    }
+  }
+
+  return true;
+}
+END_TEST(testFraction_simple)
+
+// Complex test with values exceeding Number.MAX_SAFE_INTEGER.
+BEGIN_TEST(testFraction_complex) {
+  struct {
+    int64_t numerator;
+    int64_t denominator;
+    double result;
+  } values[] = {
+      // Number.MAX_SAFE_INTEGER
+      {9007199254740991, 2, 4503599627370495.5},
+      {9007199254740992, 2, 4503599627370496},
+      {9007199254740993, 2, 4503599627370496.5},
+
+      {INT64_MAX, 2, 4611686018427387903.5},
+      {INT64_MIN, 2, -4611686018427387904.0},
+  };
+
+  for (auto [numerator, denominator, result] : values) {
+    CHECK_EQUAL(FractionToDouble(numerator, denominator), result);
+    CHECK_EQUAL(FractionToDouble(Int128{numerator}, Int128{denominator}),
+                result);
+  }
+
+  return true;
+}
+END_TEST(testFraction_complex)
+
+// Complex test with Int128 values exceeding Number.MAX_SAFE_INTEGER.
+BEGIN_TEST(testFraction_complex_int128) {
+  struct {
+    Int128 numerator;
+    Int128 denominator;
+    double result;
+  } values[] = {
+      // Divide 1 by a growing divisor.
+      {Int128{1}, Int128{1'000}, 0.001},
+      {Int128{1}, Int128{1'000'000}, 0.000'001},
+      {Int128{1}, Int128{1'000'000'000}, 0.000'000'001},
+      {Int128{1}, Int128{1'000'000'000'000}, 0.000'000'000'001},
+      {Int128{1}, Int128{1'000'000'000'000'000}, 0.000'000'000'000'001},
+      {Int128{1}, Int128{1'000'000'000'000'000'000}, 0.000'000'000'000'000'001},
+      {Int128{1}, Int128{1'000'000'000'000'000'000} * Int128{1'000},
+       0.000'000'000'000'000'000'001},
+      {Int128{1}, Int128{1'000'000'000'000'000'000} * Int128{1'000'000},
+       0.000'000'000'000'000'000'000'001},
+      {Int128{1}, Int128{1'000'000'000'000'000'000} * Int128{1'000'000'000},
+       0.000'000'000'000'000'000'000'000'001},
+      {Int128{1}, Int128{1'000'000'000'000'000'000} * Int128{1'000'000'000'000},
+       0.000'000'000'000'000'000'000'000'000'001},
+      {Int128{1},
+       Int128{1'000'000'000'000'000'000} * Int128{1'000'000'000'000'000},
+       0.000'000'000'000'000'000'000'000'000'000'001},
+      {Int128{1},
+       Int128{1'000'000'000'000'000'000} * Int128{1'000'000'000'000'000'000},
+       0.000'000'000'000'000'000'000'000'000'000'000'001},
+
+      // Divide a number not representable as an int64.
+      {Int128{0x8000'0000} << 64, Int128{1'000},
+       39614081257132168796771975.1680},
+      {Int128{0x8000'0000} << 64, Int128{1'000'000},
+       39614081257132168796771.9751680},
+      {Int128{0x8000'0000} << 64, Int128{1'000'000'000},
+       39614081257132168796.7719751680},
+      {Int128{0x8000'0000} << 64, Int128{1'000'000'000'000},
+       39614081257132168.7967719751680},
+      {Int128{0x8000'0000} << 64, Int128{1'000'000'000'000'000},
+       39614081257132.1687967719751680},
+      {Int128{0x8000'0000} << 64, Int128{1'000'000'000'000'000'000},
+       39614081257.1321687967719751680},
+      {Int128{0x8000'0000} << 64,
+       Int128{1'000'000'000'000'000'000} * Int128{1'000},
+       39614081.2571321687967719751680},
+      {Int128{0x8000'0000} << 64,
+       Int128{1'000'000'000'000'000'000} * Int128{1'000'000},
+       39614.0812571321687967719751680},
+      {Int128{0x8000'0000} << 64,
+       Int128{1'000'000'000'000'000'000} * Int128{1'000'000'000},
+       39.6140812571321687967719751680},
+      {Int128{0x8000'0000} << 64,
+       Int128{1'000'000'000'000'000'000} * Int128{1'000'000'000'000},
+       0.0396140812571321687967719751680},
+      {Int128{0x8000'0000} << 64,
+       Int128{1'000'000'000'000'000'000} * Int128{1'000'000'000'000'000},
+       0.0000396140812571321687967719751680},
+      {Int128{0x8000'0000} << 64,
+       Int128{1'000'000'000'000'000'000} * Int128{1'000'000'000'000'000'000},
+       0.0000000396140812571321687967719751680},
+
+      // Test divisor which isn't a multiple of ten.
+      {Int128{0x8000'0000} << 64, Int128{2}, 19807040628566084398385987584.0},
+      {Int128{0x8000'0000} << 64, Int128{3}, 13204693752377389598923991722.666},
+      {Int128{0x8000'0000} << 64, Int128{3'333},
+       11885412918431493788410433.5937},
+      {Int128{0x8000'0000} << 64, Int128{3'333'333},
+       11884225565562207195252.3120756},
+      {Int128{0x8000'0000} << 64, Int128{3'333'333'333},
+       11884224378328073076.864399858},
+      {Int128{0x8000'0000} << 64, Int128{3'333'333'333'333},
+       11884224377140839.0614693066343},
+      {Int128{0x8000'0000} << 64, Int128{3'333'333'333'333'333},
+       11884224377139.6518274540302643},
+      {Int128{0x8000'0000} << 64, Int128{3'333'333'333'333'333'333},
+       11884224377.1396506402200149881},
+      {Int128{0x8000'0000} << 64,
+       (Int128{3'333'333'333'333'333'333} * Int128{1'000}) + Int128{333},
+       11884224.3771396506390327809728},
+      {Int128{0x8000'0000} << 64,
+       (Int128{3'333'333'333'333'333'333} * Int128{1'000'000}) +
+           Int128{333'333},
+       11884.2243771396506390315937388},
+      {Int128{0x8000'0000} << 64,
+       (Int128{3'333'333'333'333'333'333} * Int128{1'000'000'000}) +
+           Int128{333'333'333},
+       11.884224377139650639031592551588422437713965063903159255158842243},
+      {Int128{0x8000'0000} << 64,
+       (Int128{3'333'333'333'333'333'333} * Int128{1'000'000'000'000}) +
+           Int128{333'333'333'333},
+       0.0118842243771396506390315925504},
+      {Int128{0x8000'0000} << 64,
+       (Int128{3'333'333'333'333'333'333} * Int128{1'000'000'000'000'000}) +
+           Int128{333'333'333'333'333},
+       0.0000118842243771396506390315925504},
+      {Int128{0x8000'0000} << 64,
+       (Int128{3'333'333'333'333'333'333} * Int128{1'000'000'000'000'000'000}) +
+           Int128{333'333'333'333'333'333},
+       0.0000000118842243771396506390315925504},
+  };
+
+  for (auto [numerator, denominator, result] : values) {
+    CHECK_EQUAL(FractionToDouble(numerator, denominator), result);
+  }
+
+  return true;
+}
+END_TEST(testFraction_complex_int128)
+
+#endif