#[derive(Debug)]
pub struct Rectangle {
    length: u32,
    width: u32
}

impl Rectangle {
    pub fn can_hold(&self, other: &Rectangle) -> bool {
        self.length > other.length && self.width > other.width
    }
}

#[cfg(test)]
mod tests {
    #[test]
    fn it_works() {
    }

    #[test]
    fn it_panics() {
        panic!("Make this test fail!");
    }
}

#[cfg(test)]
mod tests {
    #[test]
    fn it_works() {
    }
}

--- 
+++ 
@@ -1,23 +1,6 @@
-#[derive(Debug)]
-pub struct Rectangle {
-    length: u32,
-    width: u32
-}
-
-impl Rectangle {
-    pub fn can_hold(&self, other: &Rectangle) -> bool {
-        self.length > other.length && self.width > other.width
-    }
-}
-
 #[cfg(test)]
 mod tests {
     #[test]
     fn it_works() {
     }
-
-    #[test]
-    fn it_panics() {
-        panic!("Make this test fail!");
-    }
 }
Add struct and method for testing
