expect_column_value_z_scores_to_be_less_than work wrongly when the column contain only 0

[syrineMH]

Describe the bug i have problem implementing the expect_column_value_z_scores_to_be_less_than . My column has only 0. what i should get is the sucess of the operation but i'am getting the error below

To Reproduce Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

**Expected behavior the formula is mean\std_dev. Since the mean and column equal to 0. There can not be a division. So what i expect is to prevent the division and get a status success.

Environment (please complete the following information):

• Operating System: Windows
• Great Expectations Version: v.0.15.16

Additional context Add any other context about the problem here.

[austiezr]

Hey @syrineMH ! Thanks for raising this; we'll review internally and be in touch.

[tyler-hoffman]

I was able to reproduce this with great-expectations 0.16.16. This issue appears to not be unique to bigquery. e.g. with pandas dataframes, we get back success=False if all values in the column are the same value.

[r34ctor]

Hi @syrineMH, unfortunately this is not something we will be able to address. However, if you'd like to contribute, we'd be more than happy to support you.

[r34ctor]

We'll close this issue off for now, but please feel free to re-open it!