From 2a6ec38fd49da7ef8722c80ae4c1f63f7ffd761d Mon Sep 17 00:00:00 2001
From: ConnorSkees <39542938+ConnorSkees@users.noreply.github.com>
Date: Sat, 8 Feb 2020 18:55:48 -0500
Subject: [PATCH] Special case builtin function `opacity(number)`

---
 src/builtin/color.rs | 2 ++
 tests/color.rs       | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/src/builtin/color.rs b/src/builtin/color.rs
index f4e41c7..1d845d4 100644
--- a/src/builtin/color.rs
+++ b/src/builtin/color.rs
@@ -6,6 +6,7 @@ use num_rational::BigRational;
 
 use super::Builtin;
 use crate::color::Color;
+use crate::common::QuoteKind;
 use crate::units::Unit;
 use crate::value::{Number, Value};
 
@@ -42,6 +43,7 @@ pub(crate) fn register(f: &mut BTreeMap<String, Builtin>) {
     decl!(f "opacity", |args, _| {
         match arg!(args, 0, "color") {
             Value::Color(c) => Some(Value::Dimension(Number::new(BigRational::new(BigInt::from(c.alpha()), BigInt::from(255))), Unit::None)),
+            Value::Dimension(num, unit) => Some(Value::Ident(format!("opacity({}{})", num , unit), QuoteKind::None)),
             _ => todo!("non-color given to builtin function `opacity()`")
         }
     });
diff --git a/tests/color.rs b/tests/color.rs
index ff23f69..02397a7 100644
--- a/tests/color.rs
+++ b/tests/color.rs
@@ -56,3 +56,11 @@ test!(
     "a {\n  color: alpha(red);\n}\n",
     "a {\n  color: 1;\n}\n"
 );
+test!(
+    opacity_function_number,
+    "a {\n  color: opacity(1);\n}\n"
+);
+test!(
+    opacity_function_number_unit,
+    "a {\n  color: opacity(1px);\n}\n"
+);