added tests for throwing from .old()

test/function/old_throw.cpp

@@ -0,0 +1,46 @@
+
+// Test throw from free function .old().
+
+#include "../aux_/oteststream.hpp"
+#include <boost/contract/function.hpp>
+#include <boost/contract/guard.hpp>
+#include <boost/detail/lightweight_test.hpp>
+#include <sstream>
+
+boost::contract::aux::test::oteststream out;
+
+struct err {};
+
+void f() {
+    boost::contract::guard c = boost::contract::function()
+        .precondition([&] { out << "f::pre" << std::endl; })
+        .old([&] {
+            out << "f::old" << std::endl;
+            throw err(); // Test .old() throws.
+        })
+        .postcondition([&] { out << "f::post" << std::endl; })
+    ;
+    out << "f::body" << std::endl;
+}
+
+int main() {
+    std::ostringstream ok;
+
+    boost::contract::set_postcondition_failed(
+            [] (boost::contract::from) { throw; });
+
+    try {
+        out.str("");
+        f();
+        BOOST_TEST(false);
+    } catch(err const&) {
+        ok.str(""); ok
+            << "f::pre" << std::endl
+            << "f::old" << std::endl // Test this threw.
+        ;
+        BOOST_TEST(out.eq(ok.str()));
+    } catch(...) { BOOST_TEST(false); }
+
+    return boost::report_errors();
+}
+