add failing test case

src/lib.rs

@@ -607,9 +607,9 @@ where
                 Ok(())
             }
             TagEnd::Strikethrough => formatter.write_str("~~"),
-            TagEnd::DefinitionList => todo!(),
-            TagEnd::DefinitionListTitle => todo!(),
-            TagEnd::DefinitionListDefinition => todo!(),
+            TagEnd::DefinitionList => Ok(()),
+            TagEnd::DefinitionListTitle => Ok(()),
+            TagEnd::DefinitionListDefinition => Ok(()),
         },
         HardBreak => formatter.write_str("  \n").and(padding(formatter, &state.padding)),
         SoftBreak => formatter.write_char('\n').and(padding(formatter, &state.padding)),

tests/fmt.rs

@@ -1503,3 +1503,21 @@ key = value2
         }
     }
 }
+
+mod definition_list {
+    use super::assert_events_eq;
+
+    #[test]
+    fn round_trip() {
+        let input = r"
+First Term
+: This is the definition of the first term.
+
+Second Term
+: This is one definition of the second term.
+: This is another definition of the second term.
+";
+
+    assert_events_eq(input);
+    }
+}