revive test func

pttodoer/src/main.rs

@@ -248,13 +248,19 @@ impl Task {
       }
    }
 
+   fn set(&mut self, k: String, v: String) {
+      self.0.insert(
+         serde_yaml::Value::String(k),
+         serde_yaml::Value::String(v),
+      );
+   }
+
    fn set_value(&mut self, k: String, v: serde_yaml::Value) {
       self.0.insert(
          serde_yaml::Value::String(k),
          v
       );
    }
-
 }
 
 #[cfg(test)]