Add test for boolean keys in map

Author: dtolnay

tests/test.rs

@@ -2018,6 +2018,14 @@ fn test_deny_non_finite_f64_key() {
     assert!(serde_json::to_value(map).is_err());
 }
 
+#[test]
+fn test_boolean_key() {
+    let map = treemap!(false => 0, true => 1);
+    let j = r#"{"false":0,"true":1}"#;
+    test_encode_ok(&[(&map, j)]);
+    test_parse_ok(vec![(j, map)]);
+}
+
 #[test]
 fn test_borrowed_key() {
     let map: BTreeMap<&str, ()> = from_str("{\"borrowed\":null}").unwrap();