Cleaned up test cases

Author: WillAyd

pandas/core/generic.py

@@ -1147,10 +1147,10 @@ def rename(
         if mapper is None and index is None and columns is None:
             raise TypeError("must pass an index to rename")
 
-        if (index or columns):
+        if (index is not None or columns is not None):
             if axis is not None:
                 raise TypeError("Cannot specify both 'axis' and any of 'index' or 'columns'")
-            elif mapper:
+            elif mapper is not None:
                 raise TypeError("Cannot specify both 'mapper' and any of 'index' or 'columns'")
         else:
             # use the mapper argument

pandas/tests/frame/test_alter_axes.py

@@ -1358,11 +1358,42 @@ def test_reindex_api_equivalence(self):
             tm.assert_frame_equal(res1, res)
 
     def test_rename_positional_raises(self):
+        # GH 29136
         df = DataFrame(columns=["A", "B"])
         msg = r"rename\(\) takes from 1 to 2 positional arguments"
+
         with pytest.raises(TypeError, match=msg):
             df.rename(None, str.lower)
 
+    def test_rename_no_mappings_raises(self):
+        # GH 29136
+        df = DataFrame([[1]])
+        msg = "must pass an index to rename"
+        with pytest.raises(TypeError, match=msg):
+            df.rename()
+
+        with pytest.raises(TypeError, match=msg):
+            df.rename(None, index=None)
+
+        with pytest.raises(TypeError, match=msg):
+            df.rename(None, columns=None)
+
+        with pytest.raises(TypeError, match=msg):
+            df.rename(None, columns=None, index=None)            
+
+    def test_rename_mapper_and_positional_arguments_raises(self):
+        # GH 29136
+        df = DataFrame([[1]])
+        msg = "Cannot specify both 'mapper' and any of 'index' or 'columns'"
+        with pytest.raises(TypeError, match=msg):
+            df.rename({}, index={})
+
+        with pytest.raises(TypeError, match=msg):
+            df.rename({}, columns={})
+
+        with pytest.raises(TypeError, match=msg):
+            df.rename({}, columns={}, index={})
+
     def test_assign_columns(self, float_frame):
         float_frame["hi"] = "there"