[Sass] [SCSS] Add tests for things defined in the wrong spots.

test/sass/scss/css_test.rb

@@ -525,6 +525,17 @@ SCSS
     assert_not_parses('"{"', 'p<err># foo {a: b}')
   end
 
+  def test_no_properties_at_toplevel
+    render <<SCSS
+foo {a: b}
+a: b;
+SCSS
+    assert(false, "Expected error")
+  rescue Sass::SyntaxError => e
+    assert_equal "Properties aren't allowed at the root of a document.", e.message
+    assert_equal 2, e.sass_line
+  end
+
   private
 
   def assert_valid_string(ident)

test/sass/scss/scss_test.rb

@@ -271,4 +271,28 @@ CSS
 .foo {@include foo("bar", 12px)}
 SCSS
   end
+
+  ## Errors
+
+  def test_mixin_defs_only_at_toplevel
+    render <<SCSS
+foo {
+  @mixin bar {a: b}}
+SCSS
+    assert(false, "Expected syntax error")
+  rescue Sass::SyntaxError => e
+    assert_equal "Mixins may only be defined at the root of a document.", e.message
+    assert_equal 2, e.sass_line
+  end
+
+  def test_imports_only_at_toplevel
+    render <<SCSS
+foo {
+  @import foo.scss;}
+SCSS
+    assert(false, "Expected syntax error")
+  rescue Sass::SyntaxError => e
+    assert_equal "Import directives may only be used at the root of a document.", e.message
+    assert_equal 2, e.sass_line
+  end
 end