some more tests

src/std/list.rs

@@ -1,7 +1,7 @@
 use std::collections::HashMap;
-use std::fmt::{self, Debug, Formatter, Write};
+use std::fmt::{self, Debug, Formatter};
 use std::marker::PhantomData;
-use std::mem;
+
 use std::ptr::NonNull;
 
 use symbol::Symbol;
@@ -110,6 +110,15 @@ impl<T> List<T> {
         IntoIter(self.head)
     }
 
+    /// Returns the head of the list
+    pub fn head(&self) -> Option<&T> {
+        if let Some(ref node) = self.head {
+            unsafe { node.as_ref() }.data.as_ref()
+        } else {
+            None
+        }
+    }
+
     /// Returns the tail of the list
     pub fn tail(&self) -> Option<&T> {
         if let Some(ref node) = self.tail {
@@ -186,11 +195,23 @@ mod tests {
             prop_assert!(list.iter().eq(vec.iter()));
         }
 
+        #[test]
+        fn return_ends(vec in vec(any::<u32>(), SizeRange::default())) {
+            prop_assume!(vec.len() > 0, "can't return any elements of a 0-sized vec");
+            let mut list = List::new();
+            for item in vec.iter() {
+                list.insert(*item);
+            }
+
+            prop_assert_eq!(list.head(), vec.first(), "heads");
+            prop_assert_eq!(list.tail(), vec.last(), "tails");
+        }
+
         #[test]
         fn test_remove_by_key(mut vec in vec(any::<u32>(), SizeRange::default()), index in any::<Index>()) {
-            prop_assume!(vec.len() == 0, "can't remove from a 0-sized vec");
+            prop_assume!(vec.len() > 0, "can't remove from a 0-sized vec");
             let index = index.index(vec.len());
-            prop_assume!(index >= vec.len(), "ind is bigger than vec");
+            prop_assume!(index < vec.len(), "ind is bigger than vec");
 
             let mut list = List::new();
             let mut saved_key = None;