Added better error checking and tests for appropriate failures.

src/rail_segment.rs

@@ -6,19 +6,21 @@ use std::iter::Iterator;
 
 #[derive(Debug)]
 pub enum Error {
-    IndexError,
-    EndpointError,
-    OffsetError,
-    NeighborError,
+    IndexError(usize),
+    EndpointError(usize),
+    OffsetError(f32),
+    ConnectionError(usize),
+    StateError(f32),
 }
 
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            Self::IndexError => write!(f, "Nonexistent internal curve index"),
-            Self::EndpointError => write!(f, "Nonexistent endpoint index"),
-            Self::OffsetError => write!(f, "Invalid offset"),
-            Self::NeighborError => write!(f, "Invalid Neighbor"),
+            Self::IndexError(index) => write!(f, "Nonexistent sub-segment index: {index}."),
+            Self::EndpointError(endpoint) => write!(f, "Nonexistent endpoint index: {endpoint}."),
+            Self::OffsetError(offset) => write!(f, "Invalid offset: {offset}."),
+            Self::ConnectionError(endpoint) => write!(f, "Endpoint {endpoint} is not connected."),
+            Self::StateError(state) => write!(f, "Invalid state: {state}."),
         }
     }
 }
@@ -106,6 +108,9 @@ pub trait RailSegment {
     /** Borrow the connector associated with the given endpoint. */
     fn borrow_connection(&self, endpoint: usize) -> Result<&RailConnector, Error>;
     
+    /** Copy the connector associated with the given endpoint. */
+    fn get_connection(&self, endpoint: usize) -> Result<RailConnector, Error>;
+    
     /** Check if a connection is established on the given endpoint. */
     fn check_connection(&self, endpoint: usize) -> Result<bool, Error>;
     
@@ -132,5 +137,5 @@ pub trait RailSegment {
     fn get_state(&self) -> f32;
     
     /** Set the internal state float value. */
-    fn set_state(&mut self, value: f32);
+    fn set_state(&mut self, value: f32) -> Result<f32, Error>;
 }