Fix: Include conditional compilation for the tests.

Author: davenza

tests/add_edges_stable.rs

@@ -1,3 +1,4 @@
+#![cfg(feature = "stable_dag")]
 extern crate daggy;
 
 use daggy::WouldCycle;

tests/iterators_stable.rs

@@ -1,3 +1,4 @@
+#![cfg(feature = "stable_dag")]
 extern crate daggy;
 
 use daggy::stabledag::{StableDag, Walker};

tests/stable_indices.rs

@@ -1,8 +1,8 @@
+#![cfg(feature = "stable_dag")]
 extern crate daggy;
 
 use daggy::stabledag::StableDag;
 
-
 #[test]
 pub fn remove_nodes() {
     let mut dag = StableDag::<u32, u32, u32>::new();
@@ -12,16 +12,13 @@ pub fn remove_nodes() {
     let c = dag.add_node(3);
 
     dag.remove_node(b);
-
-
+    
     assert_eq!(Some(&0), dag.node_weight(root));
     assert_eq!(Some(&1), dag.node_weight(a));
     assert_eq!(None, dag.node_weight(b));
     assert_eq!(Some(&3), dag.node_weight(c));
-
 }
 
-
 #[test]
 fn remove_edges() {
     let mut dag = StableDag::<u32, u32, u32>::new();

tests/walkers_stable.rs

@@ -1,3 +1,4 @@
+#![cfg(feature = "stable_dag")]
 extern crate daggy;
 
 use daggy::stabledag::{StableDag, Walker};