Handle newlines more correctly

Author: jrobsonchase

rls/src/actions/format.rs

@@ -88,16 +88,27 @@ impl Rustfmt {
                 let start_line = u64::from(item.line_number_orig) - 1;
                 let end_line = start_line + u64::from(item.lines_removed);
 
+                let mut new_text = item.lines.join(newline);
+
+                // Rustfmt represents an added line as start_line == end_line, new_text == "",
+                // which is a no-op, so we need to add a terminating newline.
+                if start_line == end_line && new_text.len() == 0 {
+                    new_text.push_str(newline);
+                }
+
+                // Line deletions are represented as start_line != end_line, new_text == "".
+                // If we're not deleting a line, there should always be a terminating newline.
+                let delete_only = start_line != end_line && new_text.len() == 0;
+                if !delete_only && !new_text.ends_with(newline) {
+                    new_text.push_str(newline);
+                }
+
                 TextEdit {
                     range: Range {
                         start: Position::new(start_line, 0),
                         end: Position::new(end_line, 0),
                     },
-                    new_text: item.lines.iter().fold(String::new(), |mut acc, s| {
-                        acc.push_str(s);
-                        acc.push_str(newline);
-                        acc
-                    }),
+                    new_text,
                 }
             })
             .collect())
@@ -224,13 +235,13 @@ mod tests {
             )
         }
         // Handle single-line text wrt. added/removed trailing newline
-        test_case("fn main() {} ", vec![(0, 0, 1, 0, "fn main() {}\n\n")]);
+        test_case("fn main() {} ", vec![(0, 0, 1, 0, "fn main() {}\n")]);
         test_case("fn main() {} \n", vec![(0, 0, 1, 0, "fn main() {}\n")]);
         test_case("\nfn main() {} \n", vec![(0, 0, 2, 0, "fn main() {}\n")]);
         // Check that we send two separate edits
         test_case(
             "  struct Upper ;\n\nstruct Lower ;",
-            vec![(0, 0, 1, 0, "struct Upper;\n"), (2, 0, 3, 0, "struct Lower;\n\n")],
+            vec![(0, 0, 1, 0, "struct Upper;\n"), (2, 0, 3, 0, "struct Lower;\n")],
         );
     }
 }

tests/client.rs

@@ -935,7 +935,7 @@ fn client_format_utf16_range() {
         result.unwrap().iter().map(|edit| edit.new_text.as_str().replace('\r', "")).collect();
     // Actual formatting isn't important - what is, is that the buffer isn't
     // malformed and code stays semantically equivalent.
-    assert_eq!(new_text, vec!["/* 😢😢😢😢😢😢😢 */\nfn main() {}\n\n"]);
+    assert_eq!(new_text, vec!["/* 😢😢😢😢😢😢😢 */\nfn main() {}\n"]);
 }
 
 #[test]