add tests for nan in unary ops

src/parse/value/eval.rs

@@ -121,7 +121,6 @@ impl<'a, 'b: 'a> ValueVisitor<'a, 'b> {
             Value::Dimension(Some(n), u, should_divide) => {
                 Value::Dimension(Some(-n), u, should_divide)
             }
-            // todo: NaN test
             Value::Dimension(None, u, should_divide) => Value::Dimension(None, u, should_divide),
             v => Value::String(format!("-{}", v.to_css_string(self.span)?), QuoteKind::None),
         })

tests/nan.rs

@@ -159,3 +159,18 @@ error!(
     "@use \"sass:math\";\na {\n  color: set-nth([a], math.acos(2), b);\n}\n",
     "Error: $n: NaNdeg is not an int."
 );
+test!(
+    nan_unary_negative,
+    "a {\n  color: -(0/0);\n}\n",
+    "a {\n  color: NaN;\n}\n"
+);
+test!(
+    nan_unary_plus,
+    "a {\n  color: +(0/0);\n}\n",
+    "a {\n  color: NaN;\n}\n"
+);
+test!(
+    nan_unary_div,
+    "a {\n  color: /(0/0);\n}\n",
+    "a {\n  color: /NaN;\n}\n"
+);