Add example wasm bindgen test

tests/wasm.rs

@@ -1 +1,7 @@
+use wasm_bindgen_test::wasm_bindgen_test;
+
 wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);
+#[wasm_bindgen_test]
+fn pass() {
+    let _ = String::new();
+}