Added test to check that overloaded assignment works.

tests/run/cpp_assignment_overload.srctree

+# tag: cpp
+
+"""
+PYTHON setup.py build_ext --inplace
+PYTHON -c "from assignment_overload import test; test()"
+"""
+
+######## setup.py ########
+
+from distutils.core import setup
+from Cython.Build import cythonize
+setup(ext_modules=cythonize("*.pyx", language='c++'))
+
+######## assign.cpp ########
+
+class wrapped_int {
+public:
+  long long val;
+  wrapped_int() { val = 0; }
+  wrapped_int(long long val) { this->val = val; }
+  wrapped_int &operator=(const wrapped_int &other) {
+    this->val = other.val;
+    return *this;
+  }
+};
+
+######## assign.pxd ########
+
+cdef extern from "assign.cpp" nogil:
+    cppclass wrapped_int:
+        long long val
+        wrapped_int()
+        wrapped_int(long long val)
+        wrapped_int& operator=(const wrapped_int &other)
+
+######## assignment_overload.pyx ########
+
+from assign cimport wrapped_int
+def test():
+    cdef wrapped_int a=wrapped_int(2), b=wrapped_int(3)
+    a = b
+    assert &a != &b
+    assert a.val == b.val