1 files changed, 44 insertions, 0 deletions
diff --git a/src/lib.rs b/src/lib.rs
index 88eb0a3..fc0400e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -18,3 +18,47 @@ mod ffi
 
     include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
 }
+
+#[cfg(test)]
+mod tests
+{
+    use std::mem::transmute;
+    use std::sync::atomic::{AtomicBool, Ordering};
+
+    use super::*;
+
+    #[test]
+    fn can_set_and_use_command_function()
+    {
+        static HAS_CALLED_FUNC: AtomicBool = AtomicBool::new(false);
+
+        extern "C" fn func(x: GLint, y: GLint, width: GLsizei, height: GLsizei)
+        {
+            assert_eq!(x, 123);
+            assert_eq!(y, 9);
+            assert_eq!(width, 1920);
+            assert_eq!(height, 1080);
+
+            HAS_CALLED_FUNC.store(true, Ordering::Relaxed);
+        }
+
+        unsafe {
+            functions::glViewport = transmute(func as *const ());
+        }
+
+        unsafe {
+            Viewport(123, 9, 1920, 1080);
+        }
+
+        assert!(HAS_CALLED_FUNC.load(Ordering::Relaxed));
+    }
+
+    #[test]
+    #[should_panic]
+    fn no_set_command_function_ptr_panics()
+    {
+        unsafe {
+            AttachShader(2, 30);
+        }
+    }
+}