diff -r 68bba7c8a1b3 -r b632733724a8 samples/contravariance/src-impl/test/ContravarianceTest.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/contravariance/src-impl/test/ContravarianceTest.java	Tue Oct 18 06:55:12 2011 +0200
@@ -0,0 +1,15 @@
+package test;
+
+import api.Contravariance;
+
+public class ContravarianceTest {
+    // BEGIN: variance.contravariance.test
+    public static void main(String[] args) {
+        boolean positive = Contravariance.isPositive(10);
+        boolean negative = Contravariance.isPositive(-5);
+        System.err.println("positive = " + positive + " negative = " + negative);
+        assert positive : "10 is positive";
+        assert !negative : "-5 is negative";
+    }
+    // END: variance.contravariance.test
+}