Remove redundant overflow checks, properly handle pixel_size < 1, and implement test for invalid arguments

Author: oddbookworm

src_c/transform.c

@@ -4246,15 +4246,9 @@ surf_pixelate(PyObject *self, PyObject *args, PyObject *kwargs)
     double testWidth = round((double)src->surf->w / pixel_size);
     double testHeight = round((double)src->surf->h / pixel_size);
 
-    if (testWidth > INT_MAX || testWidth <= 0) {
-        PyErr_SetString(PyExc_OverflowError,
-                        "Cannot scale width outside the range (0, INT_MAX]");
-        return NULL;
-    }
-
-    if (testHeight > INT_MAX || testHeight <= 0) {
-        PyErr_SetString(PyExc_OverflowError,
-                        "Cannot scale height outside the range (0, INT_MAX]");
+    if (pixel_size < 1) {
+        PyErr_SetString(PyExc_ValueError,
+                        "Pixel size must be a nonnegative integer");
         return NULL;
     }
 

test/transform_test.py

@@ -1892,6 +1892,21 @@ def test_pixelate(self):
 
         self.assertTrue(surfaces_have_same_pixels(square_pixelated, square_resized))
 
+        # test a variety of arguments raise an exception
+        for arg in (0, -1):
+            with self.assertRaises(ValueError, msg=f"Running with pixel_size = {arg}"):
+                pygame.transform.pixelate(image, arg)
+
+        for arg in (-1_000_000_000_000_000_000, 1_000_000_000_000_000_000):
+            with self.assertRaises(
+                OverflowError, msg=f"Running with pixel_size = {arg}"
+            ):
+                pygame.transform.pixelate(image, arg)
+
+        for arg in ("one", 1.0, None):
+            with self.assertRaises(TypeError, msg=f"Running with pixel_size = {arg}"):
+                pygame.transform.pixelate(image, arg)
+
 
 class TransformDisplayModuleTest(unittest.TestCase):
     def setUp(self):