Add missing tests

for the following fixes/features
- compiler-research/CPyCppyy#135
- compiler-research/CPyCppyy#137
- compiler-research/CPyCppyy#142

Author: Vipul-Cariappa

test/test_lowlevel.py

@@ -517,6 +517,22 @@ def test15_templated_arrays_gmpxx(self):
         g = cppyy.gbl
         assert g.test15_templated_arrays_gmpxx.vector.value_type[g.std.vector[g.mpz_class]]
 
+    def test16_addressof_nullptr(self):
+        import cppyy
+        from cppyy import gbl
+
+        cppyy.cppdef(r"""
+        namespace LLV {
+        int x = 10;
+        int *ptr_x = &x;
+        int *ptr_null = nullptr;
+        }
+        """)
+
+        assert type(gbl.LLV.ptr_x) == cppyy._backend.LowLevelView
+        assert type(gbl.LLV.ptr_null) == cppyy._backend.LowLevelView
+        assert cppyy.addressof(gbl.LLV.ptr_x)
+        assert cppyy.addressof(gbl.LLV.ptr_null) == 0
 
 class TestMULTIDIMARRAYS:
     def setup_class(cls):
@@ -746,3 +762,32 @@ def test05_char_multidim(self):
         for i, v in enumerate(("s1", "s23", "s456")):
             assert len(ns.str_array[i]) == 8
             assert list(ns.str_array[i])[:len(v)] == list(v)
+    
+    def test06_3D_custom_struct(self):
+        import cppyy
+        from cppyy import gbl
+
+        cppyy.cppdef(r"""
+        constexpr int S = 4;
+
+        struct Klass {
+            static int i;
+            int k;
+            Klass() : k(++i) {}
+        };
+        int Klass::i = 0;
+        Klass klasses[S][S + 3][S + 7];
+
+        bool consume_klass(Klass* c, int i, int j, int k) {
+            if (c->k == ((S + 7) * (i * (S + 3) + j) + (k + 1))) return true;
+            return false;
+        }
+        """)
+
+        assert gbl.klasses
+        # assert type(gbl.klasses) == cppyy._backend.LowLevelView # FIXME: https://github.com/compiler-research/CPyCppyy/issues/141
+
+        for i in range(gbl.S):
+            for j in range(gbl.S + 3):
+                for k in range(gbl.S + 7):
+                    assert gbl.consume_klass(gbl.klasses[i][j][k], i, j, k)

test/test_templates.py

@@ -1162,6 +1162,33 @@ def test34_cstring_template_argument(self):
         assert ns.stringify["const char*"]("Aap")                    == "Aap "
         assert ns.stringify(ctypes.c_char_p(bytes("Noot", "ascii"))) == "Noot "
 
+    def test35_templated_callbacks(self):
+        import cppyy
+
+        cppyy.cppdef(
+            r"""
+        std::string foo() { return "foo!";}
+
+        std::string bar(int a, float b) {
+          return "bar(" + std::to_string(a) + ", " + std::to_string(b) + ")";
+        }
+
+        template <typename T, typename U>
+        std::string baz(T a, U b, std::string c) {
+          return "baz(" + std::to_string(a) + ", " + std::to_string(b) + ", \"" + c + "\")";
+        }
+
+        template<typename F, typename... Args>
+        std::string dataframe_define_mock(F callable, Args&&... args) {
+            return callable(std::forward<Args>(args)...);
+        }
+        """
+        )
+
+        assert cppyy.gbl.dataframe_define_mock(cppyy.gbl.foo) == "foo!"
+        assert cppyy.gbl.dataframe_define_mock(cppyy.gbl.bar, 42, 11.11) == "bar(42, 11.110000)"
+        assert cppyy.gbl.dataframe_define_mock(cppyy.gbl.baz["int", "double"], 33, 101.101, "hello") == "baz(33, 101.101000, \"hello\")"
+
 
 @mark.skipif((IS_MAC and IS_CLING), reason="setup class fails with OS X cling")
 class TestTEMPLATED_TYPEDEFS: