def test_dataframe_empty_concat():
gdf1 = DataFrame()
gdf1['a'] = []
gdf1['b'] = []
gdf2 = gdf1.copy()
gdf3 = gd.concat([gdf1, gdf2])
assert len(gdf3) == 0
assert len(gdf3.columns) == 2
def test_dataframe_copy_shallow():
# Test for copy dataframe using class method
df = DataFrame()
df['a'] = [1, 2, 3]
df2 = df.copy()
df2['b'] = [4, 2, 3]
got = df.to_string()
print(got)
expect = '''
a
0 1
1 2
2 3
'''
# values should match despite whitespace difference
assert got.split() == expect.split()