Add tests for bidirectional cursor

cli/src/tests/tree_test.rs

@@ -306,7 +306,7 @@ fn test_tree_cursor() {
         .parse(
             "
                 struct Stuff {
-                    a: A;
+                    a: A,
                     b: Option<B>,
                 }
             ",
@@ -331,6 +331,49 @@ fn test_tree_cursor() {
     assert!(cursor.goto_next_sibling());
     assert_eq!(cursor.node().kind(), "field_declaration_list");
     assert_eq!(cursor.node().is_named(), true);
+
+    assert!(cursor.goto_last_child());
+    assert_eq!(cursor.node().kind(), "}");
+    assert_eq!(cursor.node().is_named(), false);
+    assert_eq!(cursor.node().start_position(), Point { row: 4, column: 16 });
+
+    assert!(cursor.goto_previous_sibling());
+    assert_eq!(cursor.node().kind(), ",");
+    assert_eq!(cursor.node().is_named(), false);
+    assert_eq!(cursor.node().start_position(), Point { row: 3, column: 32 });
+
+    assert!(cursor.goto_previous_sibling());
+    assert_eq!(cursor.node().kind(), "field_declaration");
+    assert_eq!(cursor.node().is_named(), true);
+    assert_eq!(cursor.node().start_position(), Point { row: 3, column: 20 });
+
+    assert!(cursor.goto_previous_sibling());
+    assert_eq!(cursor.node().kind(), ",");
+    assert_eq!(cursor.node().is_named(), false);
+    assert_eq!(cursor.node().start_position(), Point { row: 2, column: 24 });
+
+    assert!(cursor.goto_previous_sibling());
+    assert_eq!(cursor.node().kind(), "field_declaration");
+    assert_eq!(cursor.node().is_named(), true);
+    assert_eq!(cursor.node().start_position(), Point { row: 2, column: 20 });
+
+    assert!(cursor.goto_previous_sibling());
+    assert_eq!(cursor.node().kind(), "{");
+    assert_eq!(cursor.node().is_named(), false);
+    assert_eq!(cursor.node().start_position(), Point { row: 1, column: 29 });
+
+    let mut copy = tree.walk();
+    copy.reset_to(cursor);
+
+    assert_eq!(copy.node().kind(), "{");
+    assert_eq!(copy.node().is_named(), false);
+
+    assert!(copy.goto_parent());
+    assert_eq!(copy.node().kind(), "field_declaration_list");
+    assert_eq!(copy.node().is_named(), true);
+
+    assert!(copy.goto_parent());
+    assert_eq!(copy.node().kind(), "struct_item");
 }
 
 #[test]