diff --git a/src/evaluate/env.rs b/src/evaluate/env.rs
index 0fde857..97e3bb2 100644
--- a/src/evaluate/env.rs
+++ b/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)
+                            format!("This module and the new module both define a variable named \"{name}\".", name = name)
                         , span).into());
                     }
                 }
diff --git a/src/parse/value.rs b/src/parse/value.rs
index 6f4960d..83c57d7 100644
--- a/src/parse/value.rs
+++ b/src/parse/value.rs
@@ -60,7 +60,7 @@ impl<'a, 'c, P: StylesheetParser<'a>> ValueParser<'a, 'c, P> {
         }
 
         if value_parser.inside_bracketed_list {
-            let start = parser.toks().cursor();
+            let bracket_start = parser.toks().cursor();
 
             parser.expect_char('[')?;
             parser.whitespace()?;
@@ -71,14 +71,12 @@ impl<'a, 'c, P: StylesheetParser<'a>> ValueParser<'a, 'c, P> {
                     separator: ListSeparator::Undecided,
                     brackets: Brackets::Bracketed,
                 })
-                .span(parser.toks_mut().span_from(start)));
+                .span(parser.toks_mut().span_from(bracket_start)));
             }
-
-            Some(start)
-        } else {
-            None
         };
 
+        value_parser.start = parser.toks().cursor();
+
         value_parser.single_expression = Some(value_parser.parse_single_expression(parser)?);
 
         let mut value = value_parser.parse_value(parser)?;
@@ -392,6 +390,7 @@ impl<'a, 'c, P: StylesheetParser<'a>> ValueParser<'a, 'c, P> {
                             self.reset_state(parser)?;
                             continue;
                         }
+                        // todo: does this branch ever get hit
                     }
 
                     if self.single_expression.is_none() {
@@ -400,7 +399,7 @@ impl<'a, 'c, P: StylesheetParser<'a>> ValueParser<'a, 'c, P> {
 
                     self.resolve_space_expressions(parser)?;
 
-                    // [resolveSpaceExpressions can modify [singleExpression_], but it
+                    // [resolveSpaceExpressions] can modify [singleExpression_], but it
                     // can't set it to null`.
                     self.comma_expressions
                         .get_or_insert_with(Default::default)
@@ -1368,62 +1367,6 @@ impl<'a, 'c, P: StylesheetParser<'a>> ValueParser<'a, 'c, P> {
         .span(span))
     }
 
-    fn try_parse_url_contents(
-        parser: &mut P,
-        name: Option<String>,
-    ) -> SassResult<Option<Interpolation>> {
-        let start = parser.toks().cursor();
-
-        if !parser.scan_char('(') {
-            return Ok(None);
-        }
-
-        parser.whitespace_without_comments();
-
-        // Match Ruby Sass's behavior: parse a raw URL() if possible, and if not
-        // backtrack and re-parse as a function expression.
-        let mut buffer = Interpolation::new();
-        buffer.add_string(name.unwrap_or_else(|| "url".to_owned()));
-        buffer.add_char('(');
-
-        while let Some(next) = parser.toks().peek() {
-            match next.kind {
-                '\\' => {
-                    buffer.add_string(parser.parse_escape(false)?);
-                }
-                '!' | '%' | '&' | '*'..='~' | '\u{80}'..=char::MAX => {
-                    parser.toks_mut().next();
-                    buffer.add_char(next.kind);
-                }
-                '#' => {
-                    if matches!(parser.toks().peek_n(1), Some(Token { kind: '{', .. })) {
-                        buffer.add_interpolation(parser.parse_single_interpolation()?);
-                    } else {
-                        parser.toks_mut().next();
-                        buffer.add_char(next.kind);
-                    }
-                }
-                ')' => {
-                    parser.toks_mut().next();
-                    buffer.add_char(next.kind);
-
-                    return Ok(Some(buffer));
-                }
-                ' ' | '\t' | '\n' | '\r' => {
-                    parser.whitespace_without_comments();
-
-                    if !parser.toks().next_char_is(')') {
-                        break;
-                    }
-                }
-                _ => break,
-            }
-        }
-
-        parser.toks_mut().set_cursor(start);
-        Ok(None)
-    }
-
     pub(crate) fn try_parse_special_function(
         parser: &mut P,
         name: &str,
@@ -1466,15 +1409,13 @@ impl<'a, 'c, P: StylesheetParser<'a>> ValueParser<'a, 'c, P> {
                 buffer.add_char('(');
             }
             "url" => {
-                return Ok(
-                    ValueParser::try_parse_url_contents(parser, None)?.map(|contents| {
-                        AstExpr::String(
-                            StringExpr(contents, QuoteKind::None),
-                            parser.toks_mut().span_from(start),
-                        )
-                        .span(parser.toks_mut().span_from(start))
-                    }),
-                )
+                return Ok(parser.try_url_contents(None)?.map(|contents| {
+                    AstExpr::String(
+                        StringExpr(contents, QuoteKind::None),
+                        parser.toks_mut().span_from(start),
+                    )
+                    .span(parser.toks_mut().span_from(start))
+                }))
             }
             _ => return Ok(None),
         }
diff --git a/src/utils/chars.rs b/src/utils/chars.rs
index afa1366..862789c 100644
--- a/src/utils/chars.rs
+++ b/src/utils/chars.rs
@@ -21,6 +21,6 @@ pub(crate) fn as_hex(c: char) -> u32 {
         '0'..='9' => c as u32 - '0' as u32,
         'A'..='F' => 10 + c as u32 - 'A' as u32,
         'a'..='f' => 10 + c as u32 - 'a' as u32,
-        _ => panic!(),
+        _ => unreachable!(),
     }
 }
diff --git a/src/utils/map_view.rs b/src/utils/map_view.rs
index e0a33ff..c3ea861 100644
--- a/src/utils/map_view.rs
+++ b/src/utils/map_view.rs
@@ -285,7 +285,7 @@ impl<V: fmt::Debug + Clone> MapView for MergedMapView<V> {
             }
         }
 
-        panic!("New entries may not be added to MergedMapView")
+        unreachable!("New entries may not be added to MergedMapView")
     }
 
     fn keys(&self) -> Vec<Identifier> {
diff --git a/src/value/mod.rs b/src/value/mod.rs
index ba85034..a98c6fd 100644
--- a/src/value/mod.rs
+++ b/src/value/mod.rs
@@ -55,26 +55,8 @@ impl PartialEq for Value {
                 Value::String(s2, ..) => s1 == s2,
                 _ => false,
             },
-            Value::Dimension(SassNumber {
-                num: n,
-                unit,
-                as_slash: _,
-            }) => match other {
-                Value::Dimension(SassNumber {
-                    num: n2,
-                    unit: unit2,
-                    as_slash: _,
-                }) => {
-                    if !unit.comparable(unit2) {
-                        return false;
-                    }
-
-                    if (*unit2 == Unit::None || *unit == Unit::None) && unit != unit2 {
-                        return false;
-                    }
-
-                    *n == n2.convert(unit2, unit)
-                }
+            Value::Dimension(n1) => match other {
+                Value::Dimension(n2) => n1 == n2,
                 _ => false,
             },
             Value::List(list1, sep1, brackets1) => match other {
diff --git a/src/value/sass_number.rs b/src/value/sass_number.rs
index f31378e..a498fd4 100644
--- a/src/value/sass_number.rs
+++ b/src/value/sass_number.rs
@@ -189,10 +189,20 @@ impl SassNumber {
 
 impl PartialEq for SassNumber {
     fn eq(&self, other: &Self) -> bool {
-        self.num == other.num && self.unit == other.unit
+        if !self.unit.comparable(&other.unit) {
+            return false;
+        }
+
+        if (other.unit == Unit::None || self.unit == Unit::None) && self.unit != other.unit {
+            return false;
+        }
+
+        self.num == other.num.convert(&other.unit, &self.unit)
     }
 }
 
+impl Eq for SassNumber {}
+
 impl Add<SassNumber> for SassNumber {
     type Output = SassNumber;
     fn add(self, rhs: SassNumber) -> Self::Output {
@@ -285,5 +295,3 @@ impl Div<SassNumber> for SassNumber {
         self.multiply_units(self.num.0 / rhs.num.0, rhs.unit.invert())
     }
 }
-
-impl Eq for SassNumber {}
diff --git a/tests/at-root.rs b/tests/at-root.rs
index 9379b2f..60e7e11 100644
--- a/tests/at-root.rs
+++ b/tests/at-root.rs
@@ -262,6 +262,15 @@ test!(
     }",
     "@unknown {\n  .bar {\n    a: b;\n  }\n}\n"
 );
+test!(
+    query_begins_with_interpolation,
+    "a {
+        @at-root (#{wi}th: rule) {
+            color: red;
+        }
+    }",
+    "a {\n  color: red;\n}\n"
+);
 error!(
     missing_closing_curly_brace,
     "@at-root {", "Error: expected \"}\"."
diff --git a/tests/color.rs b/tests/color.rs
index f6d95f9..ced9d2e 100644
--- a/tests/color.rs
+++ b/tests/color.rs
@@ -635,3 +635,26 @@ error!(
     single_arg_saturate_expects_number,
     "a {\n  color: saturate(red);\n}\n", "Error: $amount: red is not a number."
 );
+error!(
+    hex_color_starts_with_number_non_hex_digit_at_position_2,
+    "a {\n  color: #0zz;\n}\n", "Error: Expected hex digit."
+);
+error!(
+    hex_color_starts_with_number_non_hex_digit_at_position_3,
+    "a {\n  color: #00z;\n}\n", "Error: Expected hex digit."
+);
+test!(
+    hex_color_starts_with_number_non_hex_digit_at_position_4,
+    "a {\n  color: #000z;\n}\n",
+    "a {\n  color: #000 z;\n}\n"
+);
+test!(
+    #[ignore = "we don't emit 4 character hex colors correctly"]
+    hex_color_starts_with_number_non_hex_digit_at_position_5,
+    "a {\n  color: #0000z;\n}\n",
+    "a {\n  color: rgba(0, 0, 0, 0) z;\n}\n"
+);
+error!(
+    hex_color_starts_with_number_non_hex_digit_at_position_6,
+    "a {\n  color: #00000z;\n}\n", "Error: Expected hex digit."
+);
diff --git a/tests/comments.rs b/tests/comments.rs
index d915198..4785bfa 100644
--- a/tests/comments.rs
+++ b/tests/comments.rs
@@ -170,3 +170,4 @@ test!(
     "a {/**/}",
     "a { /**/ }\n"
 );
+test!(silent_comment_as_child, "a {\n// silent\n}\n", "");
diff --git a/tests/equality.rs b/tests/equality.rs
index 2b98c01..9f5287b 100644
--- a/tests/equality.rs
+++ b/tests/equality.rs
@@ -267,3 +267,10 @@ test!(
     }",
     "a {\n  color: true;\n}\n"
 );
+test!(
+    calculation_equality_converts_units,
+    "a {
+      color: calc(1in + 1rem) == calc(2.54cm + 1rem);
+    }",
+    "a {\n  color: true;\n}\n"
+);
diff --git a/tests/error.rs b/tests/error.rs
index 36e6852..50d5376 100644
--- a/tests/error.rs
+++ b/tests/error.rs
@@ -273,3 +273,7 @@ error!(
     nothing_after_dot_in_value_preceded_by_minus_sign,
     "a { color: -.", "Error: Expected digit."
 );
+error!(
+    nothing_after_bang_in_space_separated_list,
+    "a { color: a !", r#"Error: Expected "important"."#
+);
diff --git a/tests/functions.rs b/tests/functions.rs
index 09d93b1..3bc6841 100644
--- a/tests/functions.rs
+++ b/tests/functions.rs
@@ -409,6 +409,13 @@ test!(
     }",
     "a {\n  color: before;\n}\n"
 );
+test!(
+    can_parse_module_variable_declaration,
+    "@function foo() {
+        foo.$bar: red;
+    }",
+    ""
+);
 error!(
     function_no_return,
     "@function foo() {}
diff --git a/tests/imports.rs b/tests/imports.rs
index fa40860..4893912 100644
--- a/tests/imports.rs
+++ b/tests/imports.rs
@@ -523,6 +523,72 @@ test!(
 );
 error!(unclosed_single_quote, r#"@import '"#, "Error: Expected '.");
 error!(unclosed_double_quote, r#"@import ""#, "Error: Expected \".");
+error!(
+    dynamic_disallowed_inside_if,
+    r#"@if true {
+        @import "foo";
+    }"#,
+    "Error: This at-rule is not allowed here."
+);
+error!(
+    dynamic_disallowed_inside_while,
+    r#"@while true {
+        @import "foo";
+    }"#,
+    "Error: This at-rule is not allowed here."
+);
+error!(
+    dynamic_disallowed_inside_for,
+    r#"@for $i from 0 through 1 {
+        @import "foo";
+    }"#,
+    "Error: This at-rule is not allowed here."
+);
+error!(
+    dynamic_disallowed_inside_each,
+    r#"@each $i in a {
+        @import "foo";
+    }"#,
+    "Error: This at-rule is not allowed here."
+);
+test!(
+    static_allowed_inside_if,
+    r#"@if true {
+        @import "foo.css";
+    }"#,
+    "@import \"foo.css\";\n"
+);
+test!(
+    static_allowed_inside_while,
+    r#"
+    $a: 0;
+    @while $a == 0 {
+        @import "foo.css";
+        $a: 1;
+    }"#,
+    "@import \"foo.css\";\n"
+);
+test!(
+    static_allowed_inside_for,
+    r#"@for $i from 0 to 1 {
+        @import "foo.css";
+    }"#,
+    "@import \"foo.css\";\n"
+);
+test!(
+    static_allowed_inside_each,
+    r#"@each $i in a {
+        @import "foo.css";
+    }"#,
+    "@import \"foo.css\";\n"
+);
+error!(
+    dynamic_disallowed_inside_mixin,
+    r#"@mixin foo {
+        @import "foo";
+    }"#,
+    "Error: This at-rule is not allowed here."
+);
 
 // todo: edge case tests for plain css imports moved to top
 // todo: test for calling paths, e.g. `grass b\index.scss`
diff --git a/tests/list.rs b/tests/list.rs
index 51fc535..bd63c71 100644
--- a/tests/list.rs
+++ b/tests/list.rs
@@ -412,6 +412,26 @@ test!(
     "a {\n  color: [null];\n}\n",
     "a {\n  color: [];\n}\n"
 );
+test!(
+    space_separated_bracketed_list_in_parens,
+    "a {\n  color: ([a b]);\n}\n",
+    "a {\n  color: [a b];\n}\n"
+);
+test!(
+    does_not_eval_division_inside_space_separated_bracketed_list_in_parens,
+    "a {\n  color: ([1/2 1/2]);\n}\n",
+    "a {\n  color: [1/2 1/2];\n}\n"
+);
+test!(
+    comma_separated_bracketed_list_in_parens,
+    "a {\n  color: ([a, b]);\n}\n",
+    "a {\n  color: [a, b];\n}\n"
+);
+test!(
+    does_not_eval_division_inside_comma_separated_bracketed_list_in_parens,
+    "a {\n  color: ([1/2, 1/2]);\n}\n",
+    "a {\n  color: [1/2, 1/2];\n}\n"
+);
 test!(
     comma_separated_list_has_element_beginning_with_capital_A,
     "a {\n  color: a, A, \"Noto Color Emoji\";\n}\n",
diff --git a/tests/map.rs b/tests/map.rs
index 4087f73..6d3cb86 100644
--- a/tests/map.rs
+++ b/tests/map.rs
@@ -280,6 +280,27 @@ test!(
     "a {\n  color: (a: b)==(a: c);\n}\n",
     "a {\n  color: false;\n}\n"
 );
+test!(
+    important_as_key,
+    "a {\n  color: inspect((a: b, !important: c));\n}\n",
+    "a {\n  color: (a: b, !important: c);\n}\n"
+);
+error!(
+    bang_identifier_not_important_as_key,
+    "a {\n  color: inspect((a: b, !a: c));\n}\n", r#"Error: expected ")"."#
+);
+error!(
+    bang_identifier_not_important_but_starts_with_i_as_key,
+    "a {\n  color: inspect((a: b, !i: c));\n}\n", r#"Error: Expected "important"."#
+);
+error!(
+    bang_identifier_not_important_ascii_whitespace_as_key,
+    "a {\n  color: inspect((a: b, ! : c));\n}\n", r#"Error: Expected "important"."#
+);
+error!(
+    bang_identifier_not_important_loud_comment_as_key,
+    "a {\n  color: inspect((a: b, !/**/: c));\n}\n", r#"Error: expected ")"."#
+);
 test!(
     empty_with_single_line_comments,
     "$foo: (\n  \n  // :/a.b\n  \n  );
@@ -314,3 +335,7 @@ error!(
     denies_comma_separated_list_without_parens_as_key,
     "$map: (a: 1, b, c, d: e);", "Error: expected \":\"."
 );
+error!(
+    nothing_after_first_comma,
+    "$map: (a: b,", "Error: expected \")\"."
+);
diff --git a/tests/media.rs b/tests/media.rs
index e02f392..59fa1da 100644
--- a/tests/media.rs
+++ b/tests/media.rs
@@ -570,6 +570,17 @@ test!(
     }"#,
     "@media (min-width: \\0 ) {\n  a {\n    color: red;\n  }\n}\n"
 );
+test!(
+    simple_unmergeable,
+    "a {
+        @media a {
+            @media b {
+                color: red;
+            }
+        }
+    }",
+    ""
+);
 error!(
     media_query_has_quoted_closing_paren,
     r#"@media ('a)'w) {
diff --git a/tests/plain-css.rs b/tests/plain-css.rs
index d70c318..e792226 100644
--- a/tests/plain-css.rs
+++ b/tests/plain-css.rs
@@ -35,6 +35,32 @@ test!(
     "a {\n  color: 1 or 2;\n}\n",
     grass::Options::default().input_syntax(InputSyntax::Css)
 );
+test!(
+    simple_calculation,
+    "a {
+        color: calc(1 + 1);
+    }",
+    "a {\n  color: 2;\n}\n",
+    grass::Options::default().input_syntax(InputSyntax::Css)
+);
+test!(
+    simple_url_import,
+    r#"@import url("foo");"#,
+    "@import url(\"foo\");\n",
+    grass::Options::default().input_syntax(InputSyntax::Css)
+);
+test!(
+    import_no_file_extension,
+    r#"@import "foo";"#,
+    "@import \"foo\";\n",
+    grass::Options::default().input_syntax(InputSyntax::Css)
+);
+test!(
+    import_with_condition,
+    r#"@import "foo" screen and (foo: bar);"#,
+    "@import \"foo\" screen and (foo: bar);\n",
+    grass::Options::default().input_syntax(InputSyntax::Css)
+);
 test!(
     does_not_evaluate_not,
     "a {
@@ -155,6 +181,14 @@ error!(
     "Error: Operators aren't allowed in plain CSS.",
     grass::Options::default().input_syntax(InputSyntax::Css)
 );
+error!(
+    disallows_interpolation,
+    "a {
+        color: a#{b}c;
+    }",
+    "Error: Interpolation isn't allowed in plain CSS.",
+    grass::Options::default().input_syntax(InputSyntax::Css)
+);
 test!(
     allows_rgb_function,
     "a {
@@ -163,3 +197,13 @@ test!(
     "a {\n  color: rgb(true, a, b);\n}\n",
     grass::Options::default().input_syntax(InputSyntax::Css)
 );
+test!(
+    simple_supports,
+    "@supports (foo) {
+        a {
+            color: red;
+        }
+    }",
+    "@supports (foo) {\n  a {\n    color: red;\n  }\n}\n",
+    grass::Options::default().input_syntax(InputSyntax::Css)
+);
diff --git a/tests/sass.rs b/tests/sass.rs
index dde0b4b..b1c0845 100644
--- a/tests/sass.rs
+++ b/tests/sass.rs
@@ -81,6 +81,18 @@ test!(
     "/* loud */\n",
     grass::Options::default().input_syntax(InputSyntax::Sass)
 );
+test!(
+    special_mixin_and_include_characters,
+    r#"
+=foo
+    color: red
+
+a
+    +foo
+"#,
+    "a {\n  color: red;\n}\n",
+    grass::Options::default().input_syntax(InputSyntax::Sass)
+);
 error!(
     multiline_comment_in_value_position,
     r#"
@@ -90,3 +102,15 @@ loud */ red
     "Error: expected */.",
     grass::Options::default().input_syntax(InputSyntax::Sass)
 );
+error!(
+    document_starts_with_spaces,
+    r#"    "#,
+    "Error: Indenting at the beginning of the document is illegal.",
+    grass::Options::default().input_syntax(InputSyntax::Sass)
+);
+error!(
+    document_starts_with_tab,
+    "\t",
+    "Error: Indenting at the beginning of the document is illegal.",
+    grass::Options::default().input_syntax(InputSyntax::Sass)
+);
diff --git a/tests/selectors.rs b/tests/selectors.rs
index 628126a..accb7ff 100644
--- a/tests/selectors.rs
+++ b/tests/selectors.rs
@@ -927,6 +927,10 @@ error!(
     denies_optional_in_selector,
     "a !optional {}", "Error: expected \"{\"."
 );
+error!(
+    child_selector_starts_with_forward_slash,
+    "a { /b { } }", "Error: expected selector."
+);
 
 // todo:
 // [attr=url] {
diff --git a/tests/special-functions.rs b/tests/special-functions.rs
index c9b274d..221bab1 100644
--- a/tests/special-functions.rs
+++ b/tests/special-functions.rs
@@ -276,6 +276,30 @@ test!(
     "a {\n  color: calc(1dpi + 1dppx);\n}\n",
     "a {\n  color: 97dpi;\n}\n"
 );
+test!(
+    ternary_inside_calc,
+    "a {\n  color: calc(if(true, 1, unit(foo)));\n}\n",
+    "a {\n  color: 1;\n}\n"
+);
+test!(
+    retains_parens_around_var_in_calc,
+    "a {\n  color: calc((var(--a)) + 1rem);\n}\n",
+    "a {\n  color: calc((var(--a)) + 1rem);\n}\n"
+);
+test!(
+    removes_superfluous_parens_around_function_call_in_calc,
+    "a {\n  color: calc((foo(--a)) + 1rem);\n}\n",
+    "a {\n  color: calc(foo(--a) + 1rem);\n}\n"
+);
+test!(
+    calculation_inside_calc,
+    "a {\n  color: calc(calc(1px + 1rem) * calc(2px - 2in));\n}\n",
+    "a {\n  color: calc((1px + 1rem) * -190px);\n}\n"
+);
+error!(
+    escaped_close_paren_inside_calc,
+    "a {\n  color: calc(\\));\n}\n", r#"Error: Expected "(" or "."."#
+);
 error!(
     nothing_after_last_arg,
     "a { color: calc(1 + 1", r#"Error: expected "+", "-", "*", "/", or ")"."#
diff --git a/tests/unicode-range.rs b/tests/unicode-range.rs
index 0e00d4f..5e67c6b 100644
--- a/tests/unicode-range.rs
+++ b/tests/unicode-range.rs
@@ -21,6 +21,31 @@ test!(
     "a {\n  color: u+27a;\n}\n",
     "a {\n  color: u+27a;\n}\n"
 );
+test!(
+    second_element_in_list,
+    "a {\n  color: a u+55;\n}\n",
+    "a {\n  color: a u+55;\n}\n"
+);
+test!(
+    escaped_lowercase_u,
+    "a {\n  color: \\75+55;\n}\n",
+    "a {\n  color: u55;\n}\n"
+);
+test!(
+    escaped_uppercase_u,
+    "a {\n  color: \\55+55;\n}\n",
+    "a {\n  color: U55;\n}\n"
+);
+test!(
+    escaped_lowercase_u_with_space_after_escape,
+    "a {\n  color: \\75 +55;\n}\n",
+    "a {\n  color: u55;\n}\n"
+);
+test!(
+    escaped_uppercase_u_with_space_after_escape,
+    "a {\n  color: \\55 +55;\n}\n",
+    "a {\n  color: U55;\n}\n"
+);
 error!(
     interpolated_range,
     "a {\n  color: U+2A#{70}C;\n}\n", "Error: Expected end of identifier."
@@ -37,6 +62,19 @@ error!(
     length_of_6_with_question_mark,
     "a {\n  color: U+123456?;\n}\n", "Error: Expected at most 6 digits."
 );
-
-// todo: escaped u at start \75 and \55
-// with and without space
+error!(
+    nothing_after_plus_lowercase,
+    "a {\n  color: u+;\n}\n", r#"Error: Expected hex digit or "?"."#
+);
+error!(
+    nothing_after_plus_uppercase,
+    "a {\n  color: U+;\n}\n", r#"Error: Expected hex digit or "?"."#
+);
+error!(
+    second_part_of_range_is_empty,
+    "a {\n  color: u+55-;\n}\n", r#"Error: Expected hex digit."#
+);
+error!(
+    second_part_of_range_is_more_than_6_chars,
+    "a {\n  color: u+55-1234567;\n}\n", r#"Error: Expected at most 6 digits."#
+);
diff --git a/tests/url.rs b/tests/url.rs
index 1d12c13..4d55e0e 100644
--- a/tests/url.rs
+++ b/tests/url.rs
@@ -171,6 +171,11 @@ test!(
     "a {\n  color: url(#);\n}\n",
     "a {\n  color: url(#);\n}\n"
 );
+test!(
+    escaped_close_paren,
+    "a {\n  color: url(\\));\n}\n",
+    "a {\n  color: url(\\));\n}\n"
+);
 error!(
     url_nothing_after_forward_slash_in_interpolation,
     "a { color: url(#{/", "Error: Expected expression."