C++: Add a way to test the behavior of 'asExpr' and 'toString' on dataflow nodes.

cpp/ql/test/library-tests/dataflow/asExpr/test.cpp

@@ -0,0 +1,23 @@
+void take_const_ref_int(const int &);
+
+void test_materialize_temp_int()
+{
+  take_const_ref_int(42); // $ asExpr=42 numberOfNodes="42: 2" asIndirectExpr=42 numberOfIndirectNodes="42: 2"
+}
+
+struct A {};
+
+A get();
+void take_const_ref(const A &);
+
+void test1(){
+  take_const_ref(get()); // $ asExpr="call to get" numberOfNodes="call to get: 2" asIndirectExpr="call to get" numberOfIndirectNodes="call to get: 2"
+}
+
+void take_ref(A &);
+
+A& get_ref();
+
+void test2() {
+  take_ref(get_ref()); // $ asExpr="call to get_ref" asIndirectExpr="call to get_ref"
+}