1 files changed, 29 insertions, 0 deletions
diff --git a/tests/pos/t0031.scala b/tests/pos/t0031.scala
new file mode 100644
index 000000000..d4050c818
--- /dev/null
+++ b/tests/pos/t0031.scala
@@ -0,0 +1,29 @@
+object Main {
+
+    trait Ensure[a] {
+        def ensure(postcondition: a => Boolean): a
+    }
+
+    def require[a](precondition: => Boolean)(command: => a): Ensure[a] =
+        if (precondition)
+            new Ensure[a] {
+	        def ensure(postcondition: a => Boolean): a = {
+	            val result = command;
+	            if (postcondition(result)) result
+	            else sys.error("Assertion error")
+                }
+	    }
+        else
+            sys.error("Assertion error");
+
+    def arb[a](s: List[a]) =
+        require (! s.isEmpty) {
+           s.head
+        } ensure (result => s contains result);
+
+    def main(args: Array[String]) = {
+    	val s = List(1, 2);
+        Console.println(arb(s))
+    }
+
+}