2 files changed, 30 insertions, 0 deletions
diff --git a/src/descriptor.rs b/src/descriptor.rs
index 8461413..c0d3314 100644
--- a/src/descriptor.rs
+++ b/src/descriptor.rs
@@ -1,4 +1,5 @@
 #[derive(Clone, Copy, Debug)]
+#[repr(u8)]
 pub enum DescriptorType {
     Device = 1,
     Configuration = 2,
@@ -66,3 +67,30 @@ pub struct EndpointDescriptor {
     pub w_max_packet_size: u16,
     pub b_interval: u8,
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    use core::mem;
+
+    #[test]
+    fn device_descriptor_layout() {
+        assert_eq!(mem::size_of::<DeviceDescriptor>(), 18);
+    }
+
+    #[test]
+    fn configuration_descriptor_layout() {
+        assert_eq!(mem::size_of::<ConfigurationDescriptor>(), 9);
+    }
+
+    #[test]
+    fn interface_descriptor_layout() {
+        assert_eq!(mem::size_of::<InterfaceDescriptor>(), 9);
+    }
+
+    #[test]
+    fn endpoint_descriptor_layout() {
+        assert_eq!(mem::size_of::<EndpointDescriptor>(), 7);
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 551824a..742e02c 100755..100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,5 @@
+//! Traits for a hardware-agnostic USB host interface.
+
 #![no_std]
 
 mod descriptor;