improve handling of newlines around comments

src/output.rs

@@ -231,17 +231,28 @@ impl Css {
 
     fn parse_stylesheet(mut self, stmts: Vec<Stmt>) -> SassResult<Css> {
         let mut is_first = true;
+        let mut last_was_comment = false;
         for stmt in stmts {
             let v = self.parse_stmt(stmt)?;
             // this is how we print newlines between unrelated styles
             // it could probably be refactored
             if !v.is_empty() {
-                if let Some(Toplevel::MultilineComment(..)) = v.first() {
+                if matches!(v.first(), Some(Toplevel::MultilineComment(..))) {
+                    if !last_was_comment && !is_first {
+                        self.blocks.push(Toplevel::Newline);
+                    }
+
+                    last_was_comment = true;
                 } else if is_first {
-                    is_first = false;
+                    last_was_comment = false;
                 } else {
-                    self.blocks.push(Toplevel::Newline);
+                    if !last_was_comment {
+                        self.blocks.push(Toplevel::Newline);
+                    }
+
+                    last_was_comment = false;
                 }
+                is_first = false;
                 self.blocks.extend(v);
             }
         }
@@ -502,7 +513,14 @@ impl Formatter for ExpandedFormatter {
                     writeln!(buf, "{}}}", padding)?;
                 }
                 Toplevel::MultilineComment(s) => {
+                    if has_written && should_emit_newline {
+                        writeln!(buf)?;
+                    }
+
                     has_written = true;
+
+                    should_emit_newline = false;
+
                     writeln!(buf, "{}/*{}*/", padding, s)?;
                 }
                 Toplevel::Import(s) => {

tests/comments.rs

@@ -34,7 +34,7 @@ test!(
 test!(
     preserves_toplevel_comment_after,
     "a {\n  color: red;\n}\n/* foo */\n",
-    "a {\n  color: red;\n}\n/* foo */\n"
+    "a {\n  color: red;\n}\n\n/* foo */\n"
 );
 test!(
     removes_single_line_comment,
@@ -79,3 +79,22 @@ test!(
     a /** */ b {x: y}",
     "a b {\n  x: y;\n}\n\na b {\n  x: y;\n}\n\na b {\n  x: y;\n}\n\na b {\n  x: y;\n}\n"
 );
+test!(
+    comment_has_newline_above_and_not_below_when_between_two_rulesets,
+    r"a {
+      color: red;
+    }
+    
+    /**/
+    
+    a {
+      color: green;
+    }",
+    "a {\n  color: red;\n}\n\n/**/\na {\n  color: green;\n}\n"
+);
+test!(
+    no_extra_newline_between_two_comments,
+    r"/**/
+      /**/",
+    "/**/\n/**/\n"
+);

tests/each.rs

@@ -84,7 +84,7 @@ test!(
             color: $b;
         }
     }  /**/  ",
-    "/**/\n/**/\na {\n  color: a;\n}\n/**/\n\na {\n  color: b;\n}\n/**/\n"
+    "/**/\n/**/\na {\n  color: a;\n}\n\n/**/\na {\n  color: b;\n}\n\n/**/\n"
 );
 error!(
     list_of_single_map,