Add tests and whatsnew entries for (pandas-dev#18326) and (pandas-dev…

…#19981)

doc/source/whatsnew/v0.23.0.txt

@@ -1149,6 +1149,8 @@ I/O
 - Bug in :func:`read_sas` where a file with 0 variables gave an ``AttributeError`` incorrectly. Now it gives an ``EmptyDataError`` (:issue:`18184`)
 - Bug in :func:`DataFrame.to_latex()` where pairs of braces meant to serve as invisible placeholders were escaped (:issue:`18667`)
 - Bug in :func:`DataFrame.to_latex()` where a ``NaN`` in a ``MultiIndex`` would cause an ``IndexError`` or incorrect output (:issue:`14249`)
+- Bug in :func:`DataFrame.to_latex()` where a non-string index-level name would result in an ``AttributeError`` (:issue:`19981`)
+- Bug in :func:`DataFrame.to_latex()` where the combination of an index name and the `index_names=False` option would result in incorrect output (:issue:`18326`)
 - Bug in :func:`read_json` where large numeric values were causing an ``OverflowError`` (:issue:`18842`)
 - Bug in :func:`DataFrame.to_parquet` where an exception was raised if the write destination is S3 (:issue:`19134`)
 - :class:`Interval` now supported in :func:`DataFrame.to_excel` for all Excel file types (:issue:`19242`)

pandas/tests/io/formats/test_to_latex.py

@@ -643,3 +643,35 @@ def test_to_latex_multiindex_nans(self, one_row):
 \end{tabular}
 """
         assert observed == expected
+
+    def test_to_latex_non_string_index(self):
+        # GH 19981
+        observed = pd.DataFrame([[1, 2, 3]] * 2).set_index([0, 1]).to_latex()
+        expected = r"""\begin{tabular}{llr}
+\toprule
+  &   &  2 \\
+0 & 1 &    \\
+\midrule
+1 & 2 &  3 \\
+  & 2 &  3 \\
+\bottomrule
+\end{tabular}
+"""
+        assert observed == expected
+
+    def test_to_latex_midrule_location(self):
+        # GH 18326
+        df = pd.DataFrame({'a': [1, 2]})
+        df.index.name = 'foo'
+        observed = df.to_latex(index_names=False)
+        expected = r"""\begin{tabular}{lr}
+\toprule
+{} &  a \\
+\midrule
+0 &  1 \\
+1 &  2 \\
+\bottomrule
+\end{tabular}
+"""
+
+        assert observed == expected