Refactor 5 FFI test sites to NonNull / as_ref().expect() for clearer non-null contracts

Author: ciaranra

crates/pecos-qis-ffi/src/ffi.rs

@@ -1567,18 +1567,16 @@ mod tests {
 
     #[test]
     fn test_heap_alloc_and_free() {
-        let ptr = unsafe { heap_alloc(100) };
-        assert!(!ptr.is_null());
+        let ptr = std::ptr::NonNull::new(unsafe { heap_alloc(100) })
+            .expect("heap_alloc(100) should return non-null");
 
-        // SAFETY: `ptr` was just allocated by `heap_alloc(100)` and asserted non-null
-        // above; the test scope owns it exclusively until `heap_free` below.
+        // SAFETY: `ptr` owns this allocation exclusively for the test scope;
+        // `heap_alloc` returns a properly-aligned `u8` allocation.
         unsafe {
-            std::ptr::write(ptr, 42u8);
-            assert_eq!(std::ptr::read(ptr), 42u8);
+            std::ptr::write(ptr.as_ptr(), 42u8);
+            assert_eq!(std::ptr::read(ptr.as_ptr()), 42u8);
+            heap_free(ptr.as_ptr());
         }
-
-        // Free should not crash
-        unsafe { heap_free(ptr) };
     }
 
     #[test]

crates/pecos-qis-ffi/src/lib.rs

@@ -1046,11 +1046,11 @@ mod tests {
 
         // Get pending operations
         let ptr = pecos_get_pending_operations();
-        assert!(!ptr.is_null());
-
-        // SAFETY: `pecos_get_pending_operations` returns a fresh leaked Box;
-        // non-null asserted above; the test scope owns it until `pecos_free_operations`.
-        let collector = unsafe { &*ptr };
+        // SAFETY: `pecos_get_pending_operations` returns null or a leaked
+        // `Box<OperationCollector>` (properly initialised + aligned);
+        // ownership stays here until `pecos_free_operations` below.
+        let collector =
+            unsafe { ptr.as_ref() }.expect("pecos_get_pending_operations returned null");
         assert_eq!(collector.operations.len(), 2);
 
         // Free the collector
@@ -1341,10 +1341,8 @@ mod tests {
 
         // Verify operations were exported
         let ops_ptr = pecos_get_pending_operations();
-        assert!(!ops_ptr.is_null());
-        // SAFETY: `pecos_get_pending_operations` returns a fresh leaked Box;
-        // non-null asserted above; freed below via `pecos_free_operations`.
-        let ops = unsafe { &*ops_ptr };
+        // SAFETY: see `pecos_get_pending_operations` -- null-or-leaked-Box invariant.
+        let ops = unsafe { ops_ptr.as_ref() }.expect("pecos_get_pending_operations returned null");
         assert_eq!(ops.operations.len(), 2);
         unsafe { pecos_free_operations(ops_ptr) };
 
@@ -1409,21 +1407,17 @@ mod tests {
         let needed_id = pecos_wait_for_need_result(500);
         assert_eq!(needed_id, 0);
         let ops_ptr = pecos_get_pending_operations();
-        assert!(!ops_ptr.is_null());
-        // SAFETY: `pecos_get_pending_operations` returns a fresh leaked Box;
-        // non-null asserted above; freed below via `pecos_free_operations`.
-        let ops = unsafe { &*ops_ptr };
+        // SAFETY: see `pecos_get_pending_operations` -- null-or-leaked-Box invariant.
+        let ops = unsafe { ops_ptr.as_ref() }.expect("pecos_get_pending_operations returned null");
         assert_eq!(ops.operations, vec![Operation::AllocateQubit { id: 0 }]);
         unsafe { pecos_free_operations(ops_ptr) };
         pecos_signal_result_ready();
 
         let needed_id = pecos_wait_for_need_result(500);
         assert_eq!(needed_id, 1);
         let ops_ptr = pecos_get_pending_operations();
-        assert!(!ops_ptr.is_null());
-        // SAFETY: `pecos_get_pending_operations` returns a fresh leaked Box;
-        // non-null asserted above; freed below via `pecos_free_operations`.
-        let ops = unsafe { &*ops_ptr };
+        // SAFETY: see `pecos_get_pending_operations` -- null-or-leaked-Box invariant.
+        let ops = unsafe { ops_ptr.as_ref() }.expect("pecos_get_pending_operations returned null");
         assert_eq!(ops.operations, vec![Operation::Quantum(QuantumOp::H(0))]);
         unsafe { pecos_free_operations(ops_ptr) };
         pecos_signal_result_ready();