also test provided_path

tests/wasm-pack.rs

@@ -1,8 +1,6 @@
 extern crate dir_diff;
 extern crate wasm_pack;
 
-use std::fs;
-
 #[test]
 fn it_gets_the_crate_name_default_path() {
     assert!(wasm_pack::get_crate_name(".").is_ok());
@@ -27,5 +25,8 @@ fn it_creates_a_package_json_default_path() {
 #[test]
 fn it_creates_a_package_json_provided_path() {
     assert!(wasm_pack::write_package_json("./examples/js-hello-world").is_ok());
-    assert!(fs::metadata("./examples/js-hello-world/pkg/package.json").is_ok());
+    assert!(!dir_diff::is_different(
+        "./examples/js-hello-world/pkg",
+        "./test/fixtures/package-json"
+    ).unwrap());
 }