Make the unit test platform independent

Author: Jasper van Herpt

src/fs/file.rs

@@ -905,14 +905,12 @@ mod tests {
 
     #[test]
     fn async_file_create_error () {
+        let file_name = Path::new("/tmp/does_not_exist/test");
+        let expect = std::fs::File::create(file_name).unwrap_err();
+
         crate::task::block_on(async move {
-            let file_name = Path::new("/tmp/does_not_exist/test");
-            match File::create(file_name).await {
-                Ok(_) => (),
-                Err(e) => {
-                    assert_eq!("No such file or directory (os error 2)", format!("{}", e));
-                }
-            };
+            let actual = File::create(file_name).await.unwrap_err();
+            assert_eq!(format!("{}", expect), format!("{}", actual));     
         })
     }
 }