From fc974bced0cd6afd78a38fcba2d0471cfd81cf1b Mon Sep 17 00:00:00 2001
From: Claude Paroz <claude@2xlibre.net>
Date: Sat, 24 Feb 2024 12:44:29 +0100
Subject: [PATCH] Add test for passing None to add_formatter

---
 src/tablib/core.py   |  2 +-
 tests/test_tablib.py | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/tablib/core.py b/src/tablib/core.py
index 2679fd24..522a4920 100644
--- a/src/tablib/core.py
+++ b/src/tablib/core.py
@@ -643,7 +643,7 @@ def add_formatter(self, col, handler):
             else:
                 raise KeyError
 
-        if not col > self.width:
+        if col is None or col <= self.width:
             self._formatters.append((col, handler))
         else:
             raise InvalidDatasetIndex
diff --git a/tests/test_tablib.py b/tests/test_tablib.py
index 63f6d659..0c0db38d 100755
--- a/tests/test_tablib.py
+++ b/tests/test_tablib.py
@@ -578,6 +578,22 @@ def _formatter(cell_value):
         # Test once more as the result should be the same
         self.assertEqual(self.founders.dict, expected)
 
+    def test_formatters_all_cols(self):
+        """
+        Passing None as first add_formatter param apply formatter to all columns.
+        """
+
+        def _formatter(cell_value):
+            return str(cell_value).upper()
+
+        self.founders.add_formatter(None, _formatter)
+
+        self.assertEqual(self.founders.dict, [
+            {'first_name': 'JOHN', 'last_name': 'ADAMS', 'gpa': '90'},
+            {'first_name': 'GEORGE', 'last_name': 'WASHINGTON', 'gpa': '67'},
+            {'first_name': 'THOMAS', 'last_name': 'JEFFERSON', 'gpa': '50'},
+        ])
+
     def test_unicode_renders_markdown_table(self):
         # add another entry to test right field width for
         # integer