add Infinity gloabal property (#480) (#499)

boa/src/builtins/infinity/mod.rs

@@ -0,0 +1,32 @@
+//! This module implements the global `Infinity` property.
+//!
+//! The global property `Infinity` is a numeric value representing infinity.
+//!
+//! More information:
+//!  - [MDN documentation][mdn]
+//!  - [ECMAScript reference][spec]
+//!
+//! [spec]: https://tc39.es/ecma262/#sec-value-properties-of-the-global-object-infinity
+//! [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Infinity
+
+#[cfg(test)]
+mod tests;
+
+use crate::{builtins::value::Value, BoaProfiler};
+
+/// JavaScript global `Infinity` property.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub(crate) struct Infinity;
+
+impl Infinity {
+    /// The binding name of the property.
+    pub(crate) const NAME: &'static str = "Infinity";
+
+    /// Initialize the `Infinity` property on the global object.
+    #[inline]
+    pub(crate) fn init(_: &Value) -> (&str, Value) {
+        let _timer = BoaProfiler::global().start_event(Self::NAME, "init");
+
+        (Self::NAME, Value::from(f64::INFINITY))
+    }
+}

boa/src/builtins/infinity/tests.rs

@@ -0,0 +1,19 @@
+use crate::exec;
+
+#[test]
+fn infinity_exists_on_global_object_and_evaluates_to_infinity_value() {
+    let scenario = r#"
+        Infinity;
+        "#;
+
+    assert_eq!(&exec(scenario), "Infinity");
+}
+
+#[test]
+fn infinity_exists_and_equals_to_number_positive_infinity_value() {
+    let scenario = r#"
+        Number.POSITIVE_INFINITY === Infinity;
+        "#;
+
+    assert_eq!(&exec(scenario), "true");
+}

boa/src/builtins/mod.rs

@@ -7,6 +7,7 @@ pub mod console;
 pub mod error;
 pub mod function;
 pub mod global_this;
+pub mod infinity;
 pub mod json;
 pub mod math;
 pub mod nan;
@@ -24,6 +25,7 @@ pub(crate) use self::{
     boolean::Boolean,
     error::{Error, RangeError, TypeError},
     global_this::GlobalThis,
+    infinity::Infinity,
     json::Json,
     math::Math,
     nan::NaN,
@@ -57,6 +59,7 @@ pub fn init(global: &Value) {
         TypeError::init(global),
         // Global properties.
         NaN::init(global),
+        Infinity::init(global),
         GlobalThis::init(global),
     ];