BUG: assert_series_equal does not compare indices exactly

[jaapaap79]

Pandas version checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

import pandas as pd

df1 = pd.DataFrame(
    [
        (20080813, "CLZ08", 1.5),
        (20080813, "CLZ09", -0.4),
        (20080813, "CLZ08", 1.5),
        (20080814, "CLZ09", -0.4),
    ],
    columns=["date", "asset", "value"],
).set_index(["date", "asset"])["value"]

df2 = pd.DataFrame(
    [
        (20080813, "CLZ08", 1.5),
        (20080813, "CLZ09", -0.4),
        (20080814, "CLZ08", 1.5),
        (20080814, "CLZ09", -0.4),
    ],
    columns=["date", "asset", "value"],
).set_index(["date", "asset"])["value"]

pd.testing.assert_series_equal(df1, df2, check_index_type=True, check_index=True)

Issue Description

Does not raise even though index is different

Expected Behavior

Raise because index is different

Installed Versions

INSTALLED VERSIONS ------------------ commit : 8dab54d python : 3.9.13.final.0 python-bits : 64 OS : Windows OS-release : 10 Version : 10.0.19044 machine : AMD64 processor : Intel64 Family 6 Model 154 Stepping 4, GenuineIntel byteorder : little LC_ALL : None LANG : en_US.UTF-8 LOCALE : English_United States.1252

pandas : 1.5.2
numpy : 1.21.2
pytz : 2021.1
dateutil : 2.8.2
setuptools : 63.4.1
pip : 22.1.2
Cython : None
pytest : 7.1.2
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : 4.8.0
html5lib : None
pymysql : None
psycopg2 : 2.9.1
jinja2 : 2.11.3
IPython : 8.5.0
pandas_datareader: 0.10.0
bs4 : None
bottleneck : None
brotli : None
fastparquet : None
fsspec : 2022.8.2
gcsfs : None
matplotlib : 3.5.1
numba : None
numexpr : None
odfpy : None
openpyxl : 3.0.9
pandas_gbq : None
pyarrow : 9.0.0
pyreadstat : None
pyxlsb : None
s3fs : 2022.8.2
scipy : 1.7.1
snappy : None
sqlalchemy : 1.3.24
tables : None
tabulate : 0.9.0
xarray : None
xlrd : 2.0.1
xlwt : 1.3.0
zstandard : None
tzdata : None

[dicristina]

For assert_series_equal the default value for check_exact is False. assert_series_equal goes on to call assert_index_equal but it propagates its check_exact value, which is False in the example. This causes the index comparison to be done by assert_almost_equal which does not raise because the values are in fact almost equal according to the default parameters.

The most obvious solution is to use check_exact=True but you could also use a data type other than int in the first index level if possible (like str or datetime64). Also you could use an rtol smaller than the default like 4e-8.

I recommend closing this issue.

[jaapaap79]

Does it really make sense to have assert_almost_equal on the index regardless?

[dicristina]

I guess that only for a small minority of tests would it be right to compare indices approximately but I cannot point out even one such test. One could argue for check_exact to be True by default for assert_series_equal, as it is for assert_index_equal .

[jaapaap79]

Or perhaps a separate flag check_index_exact that defaults to True and gets passed through to assert_index_equal?

[topper-123]

Thanks for the bug report, @jaapaap79. This is a duplicate of #40719. I suggest continuing the discussion there.