make division with number as lhs more robust

src/value/ops.rs

@@ -624,10 +624,21 @@ impl Value {
                 Self::String(s, q) => {
                     Value::String(format!("{}{}/{}{}{}", num, unit, q, s, q), QuoteKind::None)
                 }
-                Self::BinaryOp(..) | Self::Paren(..) => {
+                Self::BinaryOp(..) | Self::Paren(..) | Self::UnaryOp(..) => {
                     Self::Dimension(num, unit).div(other.eval(span)?.node, span)?
                 }
-                _ => todo!(),
+                Self::List(..) | Self::True | Self::False | Self::Important | Self::Color(..) => {
+                    Value::String(format!("{}{}/{}", num, unit, other.to_css_string(span)?), QuoteKind::None)
+                }
+                Self::Null => Value::String(format!("{}{}/", num, unit), QuoteKind::None),
+                Self::Map(..) | Self::Function(..) => {
+                    return Err((
+                        format!("{} isn't a valid CSS value.", other.inspect(span)?),
+                        span,
+                    )
+                        .into())
+                }
+                Self::ArgList(..) => todo!(),
             },
             Self::Color(c) => match other {
                 Self::String(s, q) => {

tests/division.rs

@@ -28,3 +28,48 @@ test!(
     "a {\n  slash-after-comma: (1, / 2);\n}\n",
     "a {\n  slash-after-comma: 1, /2;\n}\n"
 );
+test!(
+    num_div_space_list,
+    "a {\n  color: 1 / (a b);\n}\n",
+    "a {\n  color: 1/a b;\n}\n"
+);
+test!(
+    num_div_comma_list,
+    "a {\n  color: 1 / (a, b);\n}\n",
+    "a {\n  color: 1/a, b;\n}\n"
+);
+test!(
+    num_div_true,
+    "a {\n  color: 1 / true;\n}\n",
+    "a {\n  color: 1/true;\n}\n"
+);
+test!(
+    num_div_false,
+    "a {\n  color: 1 / false;\n}\n",
+    "a {\n  color: 1/false;\n}\n"
+);
+test!(
+    num_div_important,
+    "a {\n  color: 1 / !important;\n}\n",
+    "a {\n  color: 1/!important;\n}\n"
+);
+test!(
+    num_div_null,
+    "a {\n  color: 1 / null;\n}\n",
+    "a {\n  color: 1/;\n}\n"
+);
+test!(
+    num_div_named_color,
+    "a {\n  color: 1 / red;\n}\n",
+    "a {\n  color: 1/red;\n}\n"
+);
+error!(
+    num_div_map,
+    "a {\n  color: 1 / (a: b);\n}\n",
+    "Error: (a: b) isn't a valid CSS value."
+);
+error!(
+    num_div_function,
+    "a {\n  color: 1 / get-function(lighten);\n}\n",
+    "Error: get-function(\"lighten\") isn't a valid CSS value."
+);