1 files changed, 21 insertions, 0 deletions
diff --git a/Test/test21/Boxing.bpl b/Test/test21/Boxing.bpl
new file mode 100644
index 00000000..08967891
--- /dev/null
+++ b/Test/test21/Boxing.bpl
@@ -0,0 +1,21 @@
+
+type Box;
+
+function box<a>(a) returns (Box);
+function unbox<a>(Box) returns (a);
+
+axiom (forall<a> x:a :: unbox(box(x)) == x);
+
+var b1: Box;
+var b2: Box;
+var b3: Box;
+
+procedure P() returns ()
+  modifies b1, b2, b3; {
+  b1 := box(13);
+  b2 := box(true);
+  b3 := box(b1);
+
+  assert unbox(b1) == 13 && unbox(b2) == true && unbox(unbox(b3)) == 13;
+  assert unbox(b1) == true;    // error
+}
+\ No newline at end of file