diff --git a/src/parse/stylesheet.rs b/src/parse/stylesheet.rs
index 8e6808e..2f5e1e4 100644
--- a/src/parse/stylesheet.rs
+++ b/src/parse/stylesheet.rs
@@ -54,7 +54,7 @@ pub(crate) trait StylesheetParser<'a>: BaseParser<'a> + Sized {
             | None => Ok(()),
             _ => {
                 self.expect_char(';')?;
-                Ok(())
+                unreachable!();
             }
         }
     }
diff --git a/tests/extend.rs b/tests/extend.rs
index 6765f9d..759a549 100644
--- a/tests/extend.rs
+++ b/tests/extend.rs
@@ -1972,6 +1972,11 @@ error!(
     }",
     "Error: complex selectors may not be extended."
 );
+error!(
+    extend_at_root_of_document,
+    "@extend a;",
+    "Error: @extend may only be used within style rules."
+);
 
 // todo: extend_loop (massive test)
 // todo: extend tests in folders
diff --git a/tests/forward.rs b/tests/forward.rs
index d35b8fa..622f062 100644
--- a/tests/forward.rs
+++ b/tests/forward.rs
@@ -208,3 +208,11 @@ fn member_import_precedence_top_level() {
         &grass::from_string(input.to_string(), &grass::Options::default().fs(&fs)).expect(input)
     );
 }
+error!(
+    after_style_rule,
+    r#"
+        a {}
+        @forward "foo";
+    "#,
+    "Error: @forward rules must be written before any other rules."
+);
\ No newline at end of file
diff --git a/tests/media.rs b/tests/media.rs
index 59fa1da..7f2b3f6 100644
--- a/tests/media.rs
+++ b/tests/media.rs
@@ -581,6 +581,42 @@ test!(
     }",
     ""
 );
+test!(
+    query_is_identifier_and_not_parens,
+    "@media screen and not (foo) {
+        a {
+            color: red;
+        }
+    }",
+    "@media screen and not (foo) {\n  a {\n    color: red;\n  }\n}\n"
+);
+test!(
+    query_is_identifier_identifier_and_parens,
+    "@media only screen and (foo) {
+        a {
+            color: red;
+        }
+    }",
+    "@media only screen and (foo) {\n  a {\n    color: red;\n  }\n}\n"
+);
+test!(
+    query_is_paren_and_paren,
+    "@media (foo) and (bar) {
+        a {
+            color: red;
+        }
+    }",
+    "@media (foo) and (bar) {\n  a {\n    color: red;\n  }\n}\n"
+);
+test!(
+    query_is_paren_or_paren,
+    "@media (foo) or (bar) {
+        a {
+            color: red;
+        }
+    }",
+    "@media (foo) or (bar) {\n  a {\n    color: red;\n  }\n}\n"
+);
 error!(
     media_query_has_quoted_closing_paren,
     r#"@media ('a)'w) {
diff --git a/tests/mixins.rs b/tests/mixins.rs
index 8625513..561488a 100644
--- a/tests/mixins.rs
+++ b/tests/mixins.rs
@@ -647,6 +647,24 @@ test!(
     }"#,
     ".environment-locality {\n  var: before;\n  var: before;\n}\n"
 );
+test!(
+    parses_extend_inside_mixin_not_in_style_rule,
+    "@mixin foo {
+        @extend a;
+    }",
+    ""
+);
+error!(
+    parses_extend_inside_content_block_not_in_style_rule,
+    "@mixin foo {
+        @content;
+    }
+
+    @include foo {
+        @extend a;
+    }",
+    "Error: @extend may only be used within style rules."
+);
 error!(
     mixin_in_function,
     "@function foo() {
diff --git a/tests/plain-css.rs b/tests/plain-css.rs
index e792226..c3ad180 100644
--- a/tests/plain-css.rs
+++ b/tests/plain-css.rs
@@ -157,6 +157,12 @@ error!(
     "Error: Sass variables aren't allowed in plain CSS.",
     grass::Options::default().input_syntax(InputSyntax::Css)
 );
+error!(
+    disallows_variable_decl,
+    "$bar: red;",
+    "Error: Sass variables aren't allowed in plain CSS.",
+    grass::Options::default().input_syntax(InputSyntax::Css)
+);
 error!(
     disallows_parent_selector_expr,
     "a {
diff --git a/tests/sass.rs b/tests/sass.rs
index b1c0845..71be04f 100644
--- a/tests/sass.rs
+++ b/tests/sass.rs
@@ -93,6 +93,16 @@ a
     "a {\n  color: red;\n}\n",
     grass::Options::default().input_syntax(InputSyntax::Sass)
 );
+test!(
+    style_rule_begins_with_plus,
+    r#"
+a
+    + b
+        color: red
+"#,
+    "a + b {\n  color: red;\n}\n",
+    grass::Options::default().input_syntax(InputSyntax::Sass)
+);
 error!(
     multiline_comment_in_value_position,
     r#"