Local app testing - selectbox format_func erroring out when using key

[sfc-gh-melnacouzi]

Checklist

• I have searched the existing issues for similar issues.
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• I have provided sufficient information below to help reproduce this issue.

Summary

If in your streamlit, there is a selectbox with format_func (returning a value different from the key), then we get the following error with streamlit app testing:

ValueError: 'key1' is not in list

I believe at.selectbox allows you to only select the displayed value (formatted), but you can't select by key.
Not sure if this is intended, but it does seem a bit counter-intuitive.

Reproducible Code Example

from streamlit.testing.v1 import AppTest
import pytest as pytest

def some_streamlit():
    import streamlit as st
    key_to_value = {'key1': 'value1', 'key2': 'value2'}
    st.selectbox('Select Value', key_to_value.keys(), format_func=lambda key: key_to_value[key], key='test')

def test_selectbox():
    at = AppTest.from_function(some_streamlit)
    at.run()
    at.selectbox('test').select('value1').run() # this works
    at.selectbox('test').select('key1').run() # this does not work
    assert not at.exception

Steps To Reproduce

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Expected Behavior

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Current Behavior

No response

Is this a regression?

• Yes, this used to work in a previous version.

Debug info

• Streamlit version:
• Python version:
• Operating System:
• Browser:

Additional Information

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[sfc-gh-jcarroll]

cc @AnOctopus - reported in Snowflake usage, I think this might be a duplicate of #7679 ? Or certainly related.