[pygobject] gtype: raise ValueError when converting an invalid GType to C

[Christoph Reiter <creiter src gnome org>]

commit eea9716a8351dead3bdcdb8a20bbf8d94f132249
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Sun Nov 25 12:17:32 2018 +0100

    gtype: raise ValueError when converting an invalid GType to C
    
    Instead of complaining that the type is wrong, which isn't the case here.

 gi/pygi-basictype.c             | 6 +++++-
 tests/test_generictreemodel.py  | 2 +-
 tests/test_overrides_gobject.py | 8 +++++---
 3 files changed, 11 insertions(+), 5 deletions(-)
---
diff --git a/gi/pygi-basictype.c b/gi/pygi-basictype.c
index 82b43c54..dafddf27 100644
--- a/gi/pygi-basictype.c
+++ b/gi/pygi-basictype.c
@@ -259,7 +259,11 @@ pygi_gtype_from_py (PyObject *py_arg, GType *type)
     GType temp = pyg_type_from_object (py_arg);
 
     if (temp == 0) {
-        PyErr_Format (PyExc_TypeError, "Must be gobject.GType, not %s",
+        if (!PyErr_Occurred ()) {
+            PyErr_SetString (PyExc_ValueError, "Invalid GType");
+            return FALSE;
+        }
+        PyErr_Format (PyExc_TypeError, "Must be GObject.GType, not %s",
                       Py_TYPE (py_arg)->tp_name);
         return FALSE;
     }
diff --git a/tests/test_generictreemodel.py b/tests/test_generictreemodel.py
index 5e9d716e..acb6028c 100644
--- a/tests/test_generictreemodel.py
+++ b/tests/test_generictreemodel.py
@@ -378,7 +378,7 @@ class TestReturnsAfterError(unittest.TestCase):
         self.assertEqual(count, 0)
 
     def test_get_column_type(self):
-        with ExceptHook(NotImplementedError, TypeError):
+        with ExceptHook(NotImplementedError, ValueError):
             col_type = self.model.get_column_type(0)
         self.assertEqual(col_type, GObject.TYPE_INVALID)
 
diff --git a/tests/test_overrides_gobject.py b/tests/test_overrides_gobject.py
index 3c7cc04b..b902564f 100644
--- a/tests/test_overrides_gobject.py
+++ b/tests/test_overrides_gobject.py
@@ -66,9 +66,11 @@ def test_value_no_init():
 
 
 def test_value_invalid_type():
-    # FIXME: this complains that the value isn't a GType
-    # GObject.Value(GObject.TYPE_INVALID)
-    pass
+    v = GObject.Value()
+    assert v.g_type == GObject.TYPE_INVALID
+    assert isinstance(GObject.TYPE_INVALID, GObject.GType)
+    with pytest.raises(ValueError, match="Invalid GType"):
+        v.init(GObject.TYPE_INVALID)
 
 
 def test_value_long():