LibJS: Add extreme value tests for cos and sin

These sometimes produce different NaN patterns which can mess up the
value encoding.

4 files changed, 35 insertions, 3 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/MathObject.cpp b/Userland/Libraries/LibJS/Runtime/MathObject.cpp
index 1679e2f14a..b76da01547 100644
--- a/Userland/Libraries/LibJS/Runtime/MathObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/MathObject.cpp
@@ -183,27 +183,53 @@ JS_DEFINE_NATIVE_FUNCTION(MathObject::trunc)
 // 21.3.2.30 Math.sin ( x ), https://tc39.es/ecma262/#sec-math.sin
 JS_DEFINE_NATIVE_FUNCTION(MathObject::sin)
 {
+    // 1. Let n be ? ToNumber(x).
     auto number = TRY(vm.argument(0).to_number(global_object));
-    if (number.is_nan())
+    // 2. If n is NaN, n is +0𝔽, or n is -0𝔽, return n.
+    if (number.is_nan() || number.is_positive_zero() || number.is_negative_zero())
+        return number;
+
+    // 3. If n is +∞𝔽 or n is -∞𝔽, return NaN.
+    if (number.is_infinity())
         return js_nan();
+
+    // 4. Return an implementation-approximated Number value representing the result of the sine of ℝ(n).
     return Value(::sin(number.as_double()));
 }
 
 // 21.3.2.12 Math.cos ( x ), https://tc39.es/ecma262/#sec-math.cos
 JS_DEFINE_NATIVE_FUNCTION(MathObject::cos)
 {
+    // 1. Let n be ? ToNumber(x).
     auto number = TRY(vm.argument(0).to_number(global_object));
-    if (number.is_nan())
+
+    // 2. If n is NaN, n is +∞𝔽, or n is -∞𝔽, return NaN.
+    if (number.is_nan() || number.is_infinity())
         return js_nan();
+
+    // 3. If n is +0𝔽 or n is -0𝔽, return 1𝔽.
+    if (number.is_positive_zero() || number.is_negative_zero())
+        return Value(1);
+
+    // 4. Return an implementation-approximated Number value representing the result of the cosine of ℝ(n).
     return Value(::cos(number.as_double()));
 }
 
 // 21.3.2.33 Math.tan ( x ), https://tc39.es/ecma262/#sec-math.tan
 JS_DEFINE_NATIVE_FUNCTION(MathObject::tan)
 {
+    // Let n be ? ToNumber(x).
     auto number = TRY(vm.argument(0).to_number(global_object));
-    if (number.is_nan())
+
+    // 2. If n is NaN, n is +0𝔽, or n is -0𝔽, return n.
+    if (number.is_nan() || number.is_positive_zero() || number.is_negative_zero())
+        return number;
+
+    // 3. If n is +∞𝔽, or n is -∞𝔽, return NaN.
+    if (number.is_infinity())
         return js_nan();
+
+    // 4. Return an implementation-approximated Number value representing the result of the tangent of ℝ(n).
     return Value(::tan(number.as_double()));
 }
 
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Math/Math.cos.js b/Userland/Libraries/LibJS/Tests/builtins/Math/Math.cos.js
index 8186bc4199..19fa430c2d 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Math/Math.cos.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Math/Math.cos.js
@@ -11,4 +11,6 @@ test("basic functionality", () => {
     expect(Math.cos([1, 2, 3])).toBeNaN();
     expect(Math.cos({})).toBeNaN();
     expect(Math.cos("foo")).toBeNaN();
+    expect(Math.cos(-Infinity)).toBeNaN();
+    expect(Math.cos(Infinity)).toBeNaN();
 });
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Math/Math.sin.js b/Userland/Libraries/LibJS/Tests/builtins/Math/Math.sin.js
index f5434d94c7..54d858e0c0 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Math/Math.sin.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Math/Math.sin.js
@@ -12,4 +12,6 @@ test("basic functionality", () => {
     expect(Math.sin([1, 2, 3])).toBeNaN();
     expect(Math.sin({})).toBeNaN();
     expect(Math.sin("foo")).toBeNaN();
+    expect(Math.sin(Infinity)).toBeNaN();
+    expect(Math.sin(-Infinity)).toBeNaN();
 });
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Math/Math.tan.js b/Userland/Libraries/LibJS/Tests/builtins/Math/Math.tan.js
index ef1f32f163..beccdc28ce 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Math/Math.tan.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Math/Math.tan.js
@@ -11,4 +11,6 @@ test("basic functionality", () => {
     expect(Math.tan([1, 2, 3])).toBeNaN();
     expect(Math.tan({})).toBeNaN();
     expect(Math.tan("foo")).toBeNaN();
+    expect(Math.tan(Infinity)).toBeNaN();
+    expect(Math.tan(-Infinity)).toBeNaN();
 });