Add test for #63

Author: chrisburr

tests/test_issues.py

@@ -0,0 +1,16 @@
+import os
+
+import pandas as pd
+import root_pandas
+
+
+def test_issue_63():
+    df = pd.DataFrame({'a': [], 'b': []})
+    root_pandas.to_root(df, 'tmp_1.root', 'my_tree')
+    df = pd.DataFrame({'a': list(range(10)), 'b': list(range(10))})
+    root_pandas.to_root(df, 'tmp_2.root', 'my_tree')
+    result = list(root_pandas.read_root(['tmp_1.root', 'tmp_2.root'], 'my_tree', where='a > 2', chunksize=1))
+    assert len(result) == 7
+    assert all(len(df) == 1 for df in result)
+    os.remove('tmp_1.root')
+    os.remove('tmp_2.root')