BUG-20591 test custom na values

Author: JustinZhengBC

pandas/io/parsers.py

@@ -1672,7 +1672,7 @@ def _convert_to_ndarrays(self, dct, na_values, na_fvalues, verbose=False,
                     try:
                         if (is_bool_dtype(cast_type) and
                                 not is_categorical_dtype(cast_type)
-                                and set(values) - set(col_na_values)):
+                                and na_count > 0):
                             raise ValueError("Bool column has NA values in "
                                              "column {column}"
                                              .format(column=c))

pandas/tests/io/parser/test_na_values.py

@@ -423,16 +423,19 @@ def test_na_values_with_dtype_str_and_na_filter(all_parsers, na_filter):
     tm.assert_frame_equal(result, expected)
 
 
-@pytest.mark.parametrize("data", [
-    "false,1\n,1\ntrue,",
-    "false,1\nnull,1\ntrue,",
-    "false,1\nnan,1\ntrue,",
+@pytest.mark.parametrize("data, na_values", [
+    ("false,1\n,1\ntrue", None),
+    ("false,1\nnull,1\ntrue", None),
+    ("false,1\nnan,1\ntrue", None),
+    ("false,1\nfoo,1\ntrue", 'foo'),
+    ("false,1\nfoo,1\ntrue", ['foo']),
+    ("false,1\nfoo,1\ntrue", {'a': 'foo'}),
 ])
-def test_cast_NA_to_bool_raises_error(all_parsers, data):
+def test_cast_NA_to_bool_raises_error(all_parsers, data, na_values):
     parser = all_parsers
     msg = ("(Bool column has NA values in column [0a])|"
            "(cannot safely convert passed user dtype of "
-           " bool for object dtyped data in column 0)")
+           "bool for object dtyped data in column 0)")
     with pytest.raises(ValueError, match=msg):
         parser.read_csv(StringIO(data), header=None, names=['a', 'b'],
-                        dtype={'a': 'bool'})
+                        dtype={'a': 'bool'}, na_values=na_values)