1 files changed, 25 insertions, 8 deletions

diff --git a/nix-test/src/lib.rs b/nix-test/src/lib.rs
index 6cd3a1f4..26d7cd4d 100644
--- a/nix-test/src/lib.rs
+++ b/nix-test/src/lib.rs
@@ -6,24 +6,41 @@ use std::ffi::CString;
 use libc::{c_int};
 
 mod ffi {
-    use libc::{c_int, c_char};
+    use libc::{c_int, c_char, size_t};
 
     #[link(name = "nixtest", kind = "static")]
     extern {
         pub fn assert_errno_eq(errno: *const c_char) -> c_int;
+        pub fn size_of(ty: *const c_char) -> size_t;
     }
 }
 
-pub fn assert_errno_eq(err: &str, val: c_int) {
+pub fn assert_errno_eq(name: &str, actual: c_int) {
     unsafe {
-        let name = CString::new(err).unwrap();
-        let actual = ffi::assert_errno_eq(name.as_ptr());
+        let cstr = CString::new(name).unwrap();
+        let expect = ffi::assert_errno_eq(cstr.as_ptr());
 
-        assert!(actual > 0);
+        assert!(expect > 0, "undefined errno {}", name);
 
-        if val != actual {
-            panic!("incorrect value for errno {}; got={}; expected={}",
-                   err, val, actual);
+        if actual != expect {
+            panic!("incorrect value for errno {}; expect={}; actual={}",
+                   name, expect, actual);
+        }
+    }
+}
+
+pub fn assert_size_of<T>(name: &str) {
+    use std::mem;
+
+    unsafe {
+        let cstr = CString::new(name).unwrap();
+        let expect = ffi::size_of(cstr.as_ptr()) as usize;
+
+        assert!(expect > 0, "undefined type {}", name);
+
+        if mem::size_of::<T>() != expect {
+            panic!("incorrectly sized type; expect={}; actual={}",
+                   expect, mem::size_of::<T>());
         }
     }
 }