Check for bad align value and raise. Wrote test for it too

Author: jmarrec

pandas/formats/style.py

@@ -1029,6 +1029,10 @@ def bar(self, subset=None, align='left', axis=0,
         elif align == 'mid':
             self.apply(self._bar_center_mid, subset=subset, axis=axis,
                        color=color, width=width, base=base)
+        else:
+            msg = ("`align` must be one of {'left', 'zero',' mid'}")
+            raise ValueError(msg)
+        
         return self
 
     def highlight_max(self, subset=None, color='yellow', axis=0):

pandas/tests/formats/test_style.py

@@ -452,6 +452,11 @@ def test_bar_align_mid_all_neg(self):
                              '#d65f5f 80.0%, #d65f5f 100.0%, transparent 100.0%)']}
         self.assertEqual(result, expected)
 
+    def test_bar_bad_align_raises(self):
+        df = pd.DataFrame({'A': [-100, -60, -30, -20]})
+        with tm.assertRaises(ValueError):
+            df.style.bar(align='poorly', color=['#d65f5f', '#5fba7d'])        
+
     def test_highlight_null(self, null_color='red'):
         df = pd.DataFrame({'A': [0, np.nan]})
         result = df.style.highlight_null()._compute().ctx