increase code coverage

crates/compiler/src/builtin/functions/color/hsl.rs

@@ -165,8 +165,6 @@ pub(crate) fn adjust_hue(mut args: ArgumentResult, visitor: &mut Visitor) -> Sas
         .assert_color_with_name("color", args.span())?;
     let degrees = angle_value(args.get_err(1, "degrees")?, "degrees", args.span())?;
 
-    dbg!(degrees);
-
     Ok(Value::Color(Arc::new(color.adjust_hue(degrees))))
 }
 

crates/compiler/src/builtin/functions/color/opacity.rs

@@ -67,7 +67,6 @@ pub(crate) fn alpha(mut args: ArgumentResult, visitor: &mut Visitor) -> SassResu
 pub(crate) fn opacity(mut args: ArgumentResult, visitor: &mut Visitor) -> SassResult<Value> {
     args.max_args(1)?;
     match args.get_err(0, "color")? {
-        Value::Dimension(SassNumber { num: n, .. }) if n.is_nan() => todo!(),
         Value::Color(c) => Ok(Value::Dimension(SassNumber::new_unitless(c.alpha()))),
         Value::Dimension(SassNumber {
             num,

crates/compiler/src/builtin/functions/list.rs

@@ -56,12 +56,7 @@ pub(crate) fn nth(mut args: ArgumentResult, visitor: &mut Visitor) -> SassResult
 pub(crate) fn list_separator(mut args: ArgumentResult, visitor: &mut Visitor) -> SassResult<Value> {
     args.max_args(1)?;
     Ok(Value::String(
-        match args.get_err(0, "list")? {
-            Value::List(_, sep, ..) => sep.name(),
-            Value::Map(..) | Value::ArgList(..) => ListSeparator::Comma.name(),
-            _ => ListSeparator::Space.name(),
-        }
-        .to_owned(),
+        args.get_err(0, "list")?.separator().name().to_owned(),
         QuoteKind::None,
     ))
 }

crates/compiler/src/evaluate/env.rs

@@ -263,7 +263,7 @@ impl Environment {
                 for name in (*self.scopes.global_variables()).borrow().keys() {
                     if (*module).borrow().var_exists(*name) {
                         return Err((
-                            format!("This module and the new module both define a variable named \"{name}\".", name = name)
+                            format!("This module and the new module both define a variable named \"${name}\".", name = name)
                         , span).into());
                     }
                 }

crates/compiler/src/evaluate/visitor.rs

@@ -829,13 +829,7 @@ impl<'a> Visitor<'a> {
         span: Span,
     ) -> SassResult<StyleSheet> {
         if let Some(name) = self.find_import(url.as_ref()) {
-            // assumption: most users use regular file paths for their imports.
-            // we do support importing syntactically invalid paths and paths that
-            // do not exist through the `Options::fs` API, so we fallback to the
-            // original name if necessary
-            let canonical = std::fs::canonicalize(&name).unwrap_or_else(|_| name.to_path_buf());
-
-            if let Some(style_sheet) = self.import_cache.get(&canonical) {
+            if let Some(style_sheet) = self.import_cache.get(&name) {
                 return Ok(style_sheet.clone());
             }
 
@@ -853,10 +847,10 @@ impl<'a> Visitor<'a> {
             self.flags
                 .set(ContextFlags::IS_USE_ALLOWED, old_is_use_allowed);
 
-            if self.files_seen.contains(&canonical) {
-                self.import_cache.insert(canonical, style_sheet.clone());
+            if self.files_seen.contains(&name) {
+                self.import_cache.insert(name, style_sheet.clone());
             } else {
-                self.files_seen.insert(canonical);
+                self.files_seen.insert(name);
             }
 
             return Ok(style_sheet);
@@ -2079,16 +2073,14 @@ impl<'a> Visitor<'a> {
                     touched: BTreeSet::new(),
                 })
             }
-            v => {
-                return Err((
-                    format!(
-                        "Variable keyword arguments must be a map (was {}).",
-                        v.inspect(arguments.span)?
-                    ),
-                    arguments.span,
-                )
-                    .into());
-            }
+            v => Err((
+                format!(
+                    "Variable keyword arguments must be a map (was {}).",
+                    v.inspect(arguments.span)?
+                ),
+                arguments.span,
+            )
+                .into()),
         }
     }
 

crates/compiler/src/lib.rs

@@ -32,7 +32,7 @@ grass input.scss
 ```
 */
 
-#![warn(clippy::all, clippy::cargo)]
+#![warn(clippy::all, clippy::cargo, clippy::dbg_macro)]
 #![deny(missing_debug_implementations)]
 #![allow(
     clippy::use_self,

crates/compiler/src/value/number.rs

@@ -2,8 +2,7 @@ use std::{
     convert::From,
     fmt, mem,
     ops::{
-        Add, AddAssign, Deref, DerefMut, Div, DivAssign, Mul, MulAssign, Neg, Rem, RemAssign, Sub,
-        SubAssign,
+        Add, AddAssign, Deref, Div, DivAssign, Mul, MulAssign, Neg, Rem, RemAssign, Sub, SubAssign,
     },
 };
 
@@ -231,12 +230,6 @@ impl Deref for Number {
     }
 }
 
-impl DerefMut for Number {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut self.0
-    }
-}
-
 macro_rules! from_integer {
     ($ty:ty) => {
         impl From<$ty> for Number {

crates/lib/src/lib.rs

@@ -32,7 +32,7 @@ grass input.scss
 */
 
 #![cfg_attr(doc, feature(doc_cfg))]
-#![warn(clippy::all, clippy::cargo)]
+#![warn(clippy::all, clippy::cargo, clippy::dbg_macro)]
 #![deny(missing_debug_implementations)]
 #![allow(
     clippy::use_self,

crates/lib/tests/color.rs

@@ -690,7 +690,75 @@ test!(
     "a {\n  color: #0000z;\n}\n",
     "a {\n  color: rgba(0, 0, 0, 0) z;\n}\n"
 );
+test!(
+    opacity_nan,
+    "a {\n  color: opacity(0/0);\n}\n",
+    "a {\n  color: opacity(NaN);\n}\n"
+);
+test!(
+    change_color_no_change,
+    "a {\n  color: change-color(red);\n}\n",
+    "a {\n  color: red;\n}\n"
+);
+test!(
+    change_color_hwb_hue,
+    "a {\n  color: change-color(red, $whiteness: 50%, $hue: 230);\n}\n",
+    "a {\n  color: #8095ff;\n}\n"
+);
 error!(
     hex_color_starts_with_number_non_hex_digit_at_position_6,
     "a {\n  color: #00000z;\n}\n", "Error: Expected hex digit."
 );
+error!(
+    opacity_arg_not_color_or_number,
+    "a {\n  color: opacity(a);\n}\n", "Error: $color: a is not a color."
+);
+error!(
+    ie_hex_str_no_args,
+    "a {\n  color: ie-hex-str();\n}\n", "Error: Missing argument $color."
+);
+error!(
+    opacify_no_args,
+    "a {\n  color: opacify();\n}\n", "Error: Missing argument $color."
+);
+error!(
+    opacify_one_arg,
+    "a {\n  color: opacify(red);\n}\n", "Error: Missing argument $amount."
+);
+error!(
+    transparentize_no_args,
+    "a {\n  color: transparentize();\n}\n", "Error: Missing argument $color."
+);
+error!(
+    transparentize_one_arg,
+    "a {\n  color: transparentize(red);\n}\n", "Error: Missing argument $amount."
+);
+error!(
+    adjust_color_sl_and_wb,
+    "a {\n  color: adjust-color(red, $saturation: 50%, $whiteness: 50%);\n}\n",
+    "Error: HSL parameters may not be passed along with HWB parameters."
+);
+error!(
+    adjust_color_rgb_and_sl,
+    "a {\n  color: adjust-color(red, $red: 50%, $saturation: 50%);\n}\n",
+    "Error: RGB parameters may not be passed along with HSL parameters."
+);
+error!(
+    adjust_color_rgb_and_wb,
+    "a {\n  color: adjust-color(red, $red: 50%, $whiteness: 50%);\n}\n",
+    "Error: RGB parameters may not be passed along with HWB parameters."
+);
+error!(
+    adjust_color_two_unknown_named_args,
+    "a {\n  color: adjust-color(red, $foo: 50%, $bar: 50%);\n}\n",
+    "Error: No arguments named $foo or $bar."
+);
+error!(
+    adjust_color_two_positional_args,
+    "a {\n  color: adjust-color(red, 50%);\n}\n",
+    "Error: Only one positional argument is allowed. All other arguments must be passed by name."
+);
+error!(
+    adjust_color_no_args,
+    "a {\n  color: adjust-color();\n}\n", "Error: Missing argument $color."
+);

crates/lib/tests/color_hsl.rs

@@ -203,7 +203,7 @@ test!(
     "a {\n  color: 100%;\n}\n"
 );
 test!(
-    saturate_one_arg,
+    saturate_one_named_arg,
     "a {\n  color: saturate($amount: 50%);\n}\n",
     "a {\n  color: saturate(50%);\n}\n"
 );
@@ -356,3 +356,84 @@ test!(
     "a {\n  color: hsl(60rad, 100%, 50%);\n}\n",
     "a {\n  color: hsl(197.7467707849deg, 100%, 50%);\n}\n"
 );
+error!(
+    hsl_one_arg_bracketed,
+    "a {\n  color: hsl([1, 2, 3]);\n}\n",
+    "Error: $channels must be an unbracketed, space-separated list."
+);
+error!(
+    hue_arg_not_color,
+    "a {\n  color: hue(1);\n}\n", "Error: $color: 1 is not a color."
+);
+error!(
+    saturation_arg_not_color,
+    "a {\n  color: saturation(1);\n}\n", "Error: $color: 1 is not a color."
+);
+error!(
+    lightness_arg_not_color,
+    "a {\n  color: lightness(1);\n}\n", "Error: $color: 1 is not a color."
+);
+error!(
+    adjust_hue_first_arg_not_color,
+    "a {\n  color: adjust-hue(1, 5deg);\n}\n", "Error: $color: 1 is not a color."
+);
+error!(
+    hue_no_args,
+    "a {\n  color: hue();\n}\n", "Error: Missing argument $color."
+);
+error!(
+    saturation_no_args,
+    "a {\n  color: saturation();\n}\n", "Error: Missing argument $color."
+);
+error!(
+    lightness_no_args,
+    "a {\n  color: lightness();\n}\n", "Error: Missing argument $color."
+);
+error!(
+    adjust_hue_no_args,
+    "a {\n  color: adjust-hue();\n}\n", "Error: Missing argument $color."
+);
+error!(
+    adjust_hue_one_arg,
+    "a {\n  color: adjust-hue(red);\n}\n", "Error: Missing argument $degrees."
+);
+error!(
+    lighten_no_args,
+    "a {\n  color: lighten();\n}\n", "Error: Missing argument $color."
+);
+error!(
+    lighten_one_arg,
+    "a {\n  color: lighten(red);\n}\n", "Error: Missing argument $amount."
+);
+error!(
+    darken_no_args,
+    "a {\n  color: darken();\n}\n", "Error: Missing argument $color."
+);
+error!(
+    darken_one_arg,
+    "a {\n  color: darken(red);\n}\n", "Error: Missing argument $amount."
+);
+error!(
+    saturate_single_named_arg_not_amount,
+    "a {\n  color: saturate($a: red);\n}\n", "Error: Missing argument $amount."
+);
+error!(
+    saturate_no_args,
+    "a {\n  color: saturate();\n}\n", "Error: Missing argument $amount."
+);
+error!(
+    saturate_one_arg,
+    "a {\n  color: saturate(red);\n}\n", "Error: $amount: red is not a number."
+);
+error!(
+    desaturate_no_args,
+    "a {\n  color: desaturate();\n}\n", "Error: Missing argument $color."
+);
+error!(
+    desaturate_one_arg,
+    "a {\n  color: desaturate(red);\n}\n", "Error: Missing argument $amount."
+);
+error!(
+    complement_no_args,
+    "a {\n  color: complement();\n}\n", "Error: Missing argument $color."
+);

crates/lib/tests/color_hwb.rs

@@ -11,6 +11,17 @@ test!(
     "@use \"sass:color\";\na {\n  color: color.blackness(white);\n}\n",
     "a {\n  color: 0%;\n}\n"
 );
+
+test!(
+    whiteness_black,
+    "@use \"sass:color\";\na {\n  color: color.whiteness(black);\n}\n",
+    "a {\n  color: 0%;\n}\n"
+);
+test!(
+    whiteness_white,
+    "@use \"sass:color\";\na {\n  color: color.whiteness(white);\n}\n",
+    "a {\n  color: 100%;\n}\n"
+);
 test!(
     blackness_approx_50_pct,
     "@use \"sass:color\";\na {\n  color: color.blackness(color.hwb(0, 0%, 50%));\n}\n",
@@ -111,3 +122,18 @@ error!(
     "@use \"sass:color\";\na {\n  color: color.hwb(0, 30%, 101%, 0.5);\n}\n",
     "Error: $blackness: Expected 101% to be within 0% and 100%."
 );
+error!(
+    blackness_no_args,
+    "@use \"sass:color\";\na {\n  color: color.blackness();\n}\n",
+    "Error: Missing argument $color."
+);
+error!(
+    whiteness_no_args,
+    "@use \"sass:color\";\na {\n  color: color.whiteness();\n}\n",
+    "Error: Missing argument $color."
+);
+error!(
+    hwb_var_channels,
+    "@use \"sass:color\";\na {\n  color: color.hwb(var(--foo));\n}\n",
+    "Error: Expected numeric channels, got \"hwb(var(--foo))\"."
+);

crates/lib/tests/debug.rs

@@ -3,3 +3,10 @@ mod macros;
 
 test!(simple_debug, "@debug 2", "");
 test!(simple_debug_with_semicolon, "@debug 2;", "");
+test!(
+    // todo: test stdout
+    debug_while_quiet,
+    "@debug 2;",
+    "",
+    grass::Options::default().quiet(true)
+);

crates/lib/tests/forward.rs

@@ -317,6 +317,23 @@ fn member_as_variable_assignment_toplevel() {
     );
 }
 
+#[test]
+fn forward_module_with_error() {
+    let mut fs = TestFs::new();
+
+    fs.add_file("_error.scss", r#"a { color: 1 + red; }"#);
+
+    let input = r#"
+        @forward "error";
+    "#;
+
+    assert_err!(
+        input,
+        r#"Error: Undefined operation "1 + red"."#,
+        grass::Options::default().fs(&fs)
+    );
+}
+
 error!(
     after_style_rule,
     r#"

crates/lib/tests/imports.rs

@@ -315,6 +315,41 @@ fn imports_absolute_scss() {
     );
 }
 
+#[test]
+fn imports_same_file_twice() {
+    let mut fs = TestFs::new();
+
+    fs.add_file("a.scss", r#"a { color: red; }"#);
+
+    let input = r#"
+        @import "a";
+        @import "a";
+    "#;
+
+    assert_eq!(
+        "a {\n  color: red;\n}\n\na {\n  color: red;\n}\n",
+        &grass::from_string(input.to_string(), &grass::Options::default().fs(&fs)).expect(input)
+    );
+}
+
+#[test]
+fn imports_same_file_thrice() {
+    let mut fs = TestFs::new();
+
+    fs.add_file("a.scss", r#"a { color: red; }"#);
+
+    let input = r#"
+        @import "a";
+        @import "a";
+        @import "a";
+    "#;
+
+    assert_eq!(
+        "a {\n  color: red;\n}\n\na {\n  color: red;\n}\n\na {\n  color: red;\n}\n",
+        &grass::from_string(input.to_string(), &grass::Options::default().fs(&fs)).expect(input)
+    );
+}
+
 #[test]
 fn imports_explicit_file_extension() {
     let mut fs = TestFs::new();

crates/lib/tests/list.rs

@@ -437,6 +437,31 @@ test!(
     "a {\n  color: a, A, \"Noto Color Emoji\";\n}\n",
     "a {\n  color: a, A, \"Noto Color Emoji\";\n}\n"
 );
+test!(
+    list_separator_of_map,
+    "a {\n  color: list-separator((a: b, c: d));\n}\n",
+    "a {\n  color: comma;\n}\n"
+);
+test!(
+    list_separator_of_empty_parens,
+    "a {\n  color: list-separator(());\n}\n",
+    "a {\n  color: space;\n}\n"
+);
+test!(
+    list_separator_of_unquoted_string,
+    "a {\n  color: list-separator(a);\n}\n",
+    "a {\n  color: space;\n}\n"
+);
+test!(
+    list_separator_of_arglist,
+    "@function foo($a...) {
+        @return list-separator($a);
+    }
+    a {
+        color: foo();
+    }",
+    "a {\n  color: comma;\n}\n"
+);
 test!(
     list_separator_of_empty_list_after_join,
     "a {

crates/lib/tests/macros.rs

@@ -112,6 +112,19 @@ macro_rules! assert_err {
             ),
         }
     };
+    ($input:expr, $err:expr, $options:expr) => {
+        match grass::from_string($input.to_string(), &$options) {
+            Ok(..) => panic!("did not fail"),
+            Err(e) => assert_eq!(
+                $err,
+                e.to_string()
+                    .chars()
+                    .take_while(|c| *c != '\n')
+                    .collect::<String>()
+                    .as_str()
+            ),
+        }
+    };
 }
 
 /// Suitable for simple import tests. Does not properly implement path resolution --

crates/lib/tests/math.rs

@@ -158,3 +158,31 @@ error!(
     comparable_non_number_arg_last,
     "a {\n  color: comparable(1, b);\n}\n", "Error: $number2: b is not a number."
 );
+error!(
+    percentage_no_args,
+    "a {\n  color: percentage();\n}\n", "Error: Missing argument $number."
+);
+error!(
+    round_no_args,
+    "a {\n  color: round();\n}\n", "Error: Missing argument $number."
+);
+error!(
+    ceil_no_args,
+    "a {\n  color: ceil();\n}\n", "Error: Missing argument $number."
+);
+error!(
+    floor_no_args,
+    "a {\n  color: floor();\n}\n", "Error: Missing argument $number."
+);
+error!(
+    abs_no_args,
+    "a {\n  color: abs();\n}\n", "Error: Missing argument $number."
+);
+error!(
+    comparable_no_args,
+    "a {\n  color: comparable();\n}\n", "Error: Missing argument $number1."
+);
+error!(
+    comparable_one_arg,
+    "a {\n  color: comparable(1);\n}\n", "Error: Missing argument $number2."
+);

crates/lib/tests/meta.rs

@@ -26,6 +26,23 @@ test!(
     "a {\n  color: if(false, 1, 2);\n}\n",
     "a {\n  color: 2;\n}\n"
 );
+test!(
+    if_is_global_fn,
+    "a {
+        $a: get-function(if);
+        color: call($a, true, 2, 3);
+        color: call($a, false, 2, 3);
+    }",
+    "a {\n  color: 2;\n  color: 3;\n}\n"
+);
+error!(
+    if_inside_call_does_not_lazily_eval_args,
+    "a {
+        $a: get-function(if);
+        color: call($a, true, 2, red % 5);
+    }",
+    "Error: Undefined operation \"red % 5\"."
+);
 test!(
     feature_exists_dbl_quoted,
     "a {\n  color: feature-exists(\"at-error\")\n}\n",
@@ -359,5 +376,17 @@ test!(
     }",
     "a {\n  color: get-function(\"empty\");\n}\n"
 );
+error!(
+    feature_exists_no_args,
+    "a {\n  color: feature-exists();\n}\n", "Error: Missing argument $feature."
+);
+error!(
+    unit_no_args,
+    "a {\n  color: unit();\n}\n", "Error: Missing argument $number."
+);
+error!(
+    unitless_no_args,
+    "a {\n  color: unitless();\n}\n", "Error: Missing argument $number."
+);
 
 // todo: if() with different combinations of named and positional args

crates/lib/tests/modulo.rs

@@ -175,6 +175,11 @@ test!(
     "a {\n  color: -5 % (-1/0);\n}\n",
     "a {\n  color: NaN;\n}\n"
 );
+test!(
+    zero_mod_negative,
+    "a {\n  color: 0 % -5;\n}\n",
+    "a {\n  color: 0;\n}\n"
+);
 error!(
     calculation_mod_calculation,
     "a {\n  color: calc(1rem + 1px) % calc(1rem + 1px);\n}\n",

crates/lib/tests/plain-css-fn.rs

@@ -81,6 +81,16 @@ test!(
     "a {\n  color: or(foo);\n}\n",
     "a {\n  color: or(foo);\n}\n"
 );
+test!(
+    rest_arg,
+    "a {
+        color: foo(red...);
+        color: foo(a, red...);
+        color: f#{o}o(red...);
+        color: f#{o}o(a, red...);
+    }",
+    "a {\n  color: foo(red);\n  color: foo(a, red);\n  color: foo(red);\n  color: foo(a, red);\n}\n"
+);
 error!(
     denies_keyword_arguments_to_interpolated_function,
     "a {\n  color: f#{o}o($a: red);\n}\n",

crates/lib/tests/special-functions.rs

@@ -251,6 +251,16 @@ test!(
     "a {\n  color: calc(1% + 3px - 2px);\n}\n",
     "a {\n  color: calc(1% + 3px - 2px);\n}\n"
 );
+test!(
+    inspect_calc,
+    "a {\n  color: inspect(calc(1% + 3px - 2px));\n}\n",
+    "a {\n  color: calc(1% + 3px - 2px);\n}\n"
+);
+test!(
+    calc_ne_number,
+    "a {\n  color: calc(1% + 3px - 2px) == 1px;\n}\n",
+    "a {\n  color: false;\n}\n"
+);
 test!(
     calc_num_plus_interpolation,
     "a {\n  color: calc(1 + #{c});\n}\n",

crates/lib/tests/strings.rs

@@ -254,3 +254,48 @@ test!(
     "a {\n  color: str-index(\"c\\0308 a\", \"a\");\n}\n",
     "a {\n  color: 3;\n}\n"
 );
+error!(
+    to_lower_case_no_args,
+    "a {\n  color: to_lower_case();\n}\n", "Error: Missing argument $string."
+);
+error!(
+    str_length_no_args,
+    "a {\n  color: str_length();\n}\n", "Error: Missing argument $string."
+);
+error!(
+    quote_no_args,
+    "a {\n  color: quote();\n}\n", "Error: Missing argument $string."
+);
+error!(
+    unquote_no_args,
+    "a {\n  color: unquote();\n}\n", "Error: Missing argument $string."
+);
+error!(
+    str_slice_no_args,
+    "a {\n  color: str_slice();\n}\n", "Error: Missing argument $string."
+);
+error!(
+    str_index_no_args,
+    "a {\n  color: str_index();\n}\n", "Error: Missing argument $string."
+);
+error!(
+    str_insert_no_args,
+    "a {\n  color: str_insert();\n}\n", "Error: Missing argument $string."
+);
+test!(
+    unique_id_is_unique,
+    "$init: unique-id();
+    @for $_ from 0 to 100 {
+        @if $init == unique-id() {
+            @error 'got duplicate unique id: #{$init}';
+        }
+    }",
+    ""
+);
+test!(
+    unique_id_is_valid_identifier,
+    "@for $_ from 0 to 100 {
+        #{unique-id()} {}
+    }",
+    ""
+);

crates/lib/tests/supports.rs

@@ -138,7 +138,7 @@ test!(
 );
 test!(supports_empty_body, "@supports (a: b) {}", "");
 test!(
-    does_not_simplify_calculation_in_args,
+    calculation_not_in_declaration,
     "@supports (calc(1 + 1)) {
         a {
             color: red;
@@ -146,6 +146,24 @@ test!(
     }",
     "@supports (calc(1 + 1)) {\n  a {\n    color: red;\n  }\n}\n"
 );
+test!(
+    ident_addition_on_rhs_of_declaration,
+    "@supports (a: a + b) {
+        a {
+            color: red;
+        }
+    }",
+    "@supports (a: ab) {\n  a {\n    color: red;\n  }\n}\n"
+);
+test!(
+    calculation_on_rhs_of_declaration,
+    "@supports (a: calc(1px + 1px)) {
+        a {
+            color: red;
+        }
+    }",
+    "@supports (a: calc(1px + 1px)) {\n  a {\n    color: red;\n  }\n}\n"
+);
 error!(
     supports_inside_declaration_body,
     "@mixin foo() {

crates/lib/tests/use.rs

@@ -640,4 +640,66 @@ fn module_functions_through_forward() {
     );
 }
 
+#[test]
+fn use_variable_declared_in_this_and_other_module() {
+    let mut fs = TestFs::new();
+
+    fs.add_file(
+        "_a.scss",
+        r#"
+        $a: blue;
+    "#,
+    );
+
+    let input = r#"
+        $a: red;
+        @use "a" as *;
+
+        a {
+            color: $a;
+        }
+    "#;
+
+    assert_err!(
+        input,
+        "Error: This module and the new module both define a variable named \"$a\".",
+        grass::Options::default().fs(&fs)
+    );
+}
+
+#[test]
+#[ignore = "we don't check for this"]
+fn use_variable_declared_in_two_modules() {
+    let mut fs = TestFs::new();
+
+    fs.add_file(
+        "_a.scss",
+        r#"
+        $a: blue;
+    "#,
+    );
+
+    fs.add_file(
+        "_b.scss",
+        r#"
+        $a: red;
+    "#,
+    );
+
+    let input = r#"
+        @use "a" as *;
+        @use "b" as *;
+
+        a {
+            color: $a;
+        }
+    "#;
+
+    assert_err!(
+        input,
+        "Error: This variable is available from multiple global modules.",
+        grass::Options::default().fs(&fs)
+    );
+}
+
 // todo: refactor these tests to use testfs where possible

crates/lib/tests/warn.rs

@@ -2,3 +2,10 @@
 mod macros;
 
 test!(simple_warn, "@warn 2", "");
+test!(
+    // todo: test stdout
+    warn_while_quiet,
+    "@warn 2;",
+    "",
+    grass::Options::default().quiet(true)
+);