add some tests for reports spanning multiple lines

Author: narpfel

src/write.rs

@@ -1071,6 +1071,30 @@ mod tests {
         "###);
     }
 
+    #[test]
+    fn two_labels_without_messages_on_different_lines() {
+        let source = "apple\n== orange;";
+        let msg = remove_trailing(
+            Report::build(ReportKind::Error, 0..0)
+                .with_config(no_color_and_ascii())
+                .with_message("can't compare apples with oranges")
+                .with_label(Label::new(0..5))
+                .with_label(Label::new(9..15))
+                .finish()
+                .write_to_string(Source::from(source)),
+        );
+        assert_snapshot!(msg, @r###"
+        Error: can't compare apples with oranges
+           ,-[ <unknown>:1:1 ]
+           |
+         1 | apple
+           | ^^^^^
+         2 | == orange;
+           |    ^^^^^^
+        ---'
+        "###);
+    }
+
     #[test]
     fn two_labels_with_messages() {
         let source = "apple == orange;";
@@ -1097,6 +1121,32 @@ mod tests {
         "###);
     }
 
+    #[test]
+    fn two_labels_with_messages_on_different_lines() {
+        let source = "apple ==\norange;";
+        let msg = remove_trailing(
+            Report::build(ReportKind::Error, 0..0)
+                .with_config(no_color_and_ascii())
+                .with_message("can't compare apples with oranges")
+                .with_label(Label::new(0..5).with_message("This is an apple"))
+                .with_label(Label::new(9..15).with_message("This is an orange"))
+                .finish()
+                .write_to_string(Source::from(source)),
+        );
+        assert_snapshot!(msg, @r###"
+        Error: can't compare apples with oranges
+           ,-[ <unknown>:1:1 ]
+           |
+         1 | apple ==
+           | ^^|^^
+           |   `---- This is an apple
+         2 | orange;
+           | ^^^|^^
+           |    `---- This is an orange
+        ---'
+        "###);
+    }
+
     #[test]
     fn multi_byte_chars() {
         let source = "äpplë == örängë;";