1 files changed, 81 insertions, 0 deletions
diff --git a/js/src/tests/ecma_6/Math/fround.js b/js/src/tests/ecma_6/Math/fround.js
new file mode 100644
index 000000000..353f798d5
--- /dev/null
+++ b/js/src/tests/ecma_6/Math/fround.js
@@ -0,0 +1,81 @@
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/
+ */
+
+// Some tests regarding conversion to Float32
+assertEq(Math.fround(), NaN);
+
+// Special values
+assertEq(Math.fround(NaN), NaN);
+assertEq(Math.fround(-Infinity), -Infinity);
+assertEq(Math.fround(Infinity), Infinity);
+assertEq(Math.fround(-0), -0);
+assertEq(Math.fround(+0), +0);
+
+// Polyfill function for Float32 conversion
+var toFloat32 = (function() {
+    var f32 = new Float32Array(1);
+    function f(x) {
+        f32[0] = x;
+        return f32[0];
+    }
+    return f;
+})();
+
+// A test on a certain range of numbers, including big numbers, so that
+// we get a loss in precision for some of them.
+for (var i = 0; i < 64; ++i) {
+    var p = Math.pow(2, i) + 1;
+    assertEq(Math.fround(p), toFloat32(p));
+    assertEq(Math.fround(-p), toFloat32(-p));
+}
+
+/********************************************
+/* Tests on maximal Float32 / Double values *
+/*******************************************/
+function maxValue(exponentWidth, significandWidth) {
+    var n = 0;
+    var maxExp = Math.pow(2, exponentWidth - 1) - 1;
+    for (var i = significandWidth; i >= 0; i--)
+        n += Math.pow(2, maxExp - i);
+    return n;
+}
+
+var DBL_MAX = maxValue(11, 52);
+assertEq(DBL_MAX, Number.MAX_VALUE); // sanity check
+
+// Finite as a double, too big for a float
+assertEq(Math.fround(DBL_MAX), Infinity);
+
+var FLT_MAX = maxValue(8, 23);
+assertEq(Math.fround(FLT_MAX), FLT_MAX);
+assertEq(Math.fround(FLT_MAX + Math.pow(2, Math.pow(2, 8 - 1) - 1 - 23 - 2)), FLT_MAX); // round-nearest rounds down to FLT_MAX
+assertEq(Math.fround(FLT_MAX + Math.pow(2, Math.pow(2, 8 - 1) - 1 - 23 - 1)), Infinity); // no longer rounds down to FLT_MAX
+
+/*********************************************************
+/******* Tests on denormalizations and roundings *********
+/********************************************************/
+
+function minValue(exponentWidth, significandWidth) {
+    return Math.pow(2, -(Math.pow(2, exponentWidth - 1) - 2) - significandWidth);
+}
+
+var DBL_MIN = Math.pow(2, -1074);
+assertEq(DBL_MIN, Number.MIN_VALUE); // sanity check
+
+// Too small for a float
+assertEq(Math.fround(DBL_MIN), 0);
+
+var FLT_MIN = minValue(8, 23);
+assertEq(Math.fround(FLT_MIN), FLT_MIN);
+
+assertEq(Math.fround(FLT_MIN / 2), 0); // halfway, round-nearest rounds down to 0 (even)
+assertEq(Math.fround(FLT_MIN / 2 + Math.pow(2, -202)), FLT_MIN); // first double > FLT_MIN / 2, rounds up to FLT_MIN
+
+assertEq(Math.fround(-FLT_MIN), -FLT_MIN);
+
+assertEq(Math.fround(-FLT_MIN / 2), -0); // halfway, round-nearest rounds up to -0 (even)
+assertEq(Math.fround(-FLT_MIN / 2 - Math.pow(2, -202)), -FLT_MIN); // first double < -FLT_MIN / 2, rounds down to -FLT_MIN
+
+reportCompare(0, 0, "ok");