[flake8-simplify] Only trigger SIM401 on known dictionaries (SIM401)

[junhsonjb]

Summary

This change resolves #15814 to ensure that SIM401 is only triggered on known dictionary types. Before, the rule was getting triggered even on types that resemble a dictionary but are not actually a dictionary.

I did this using the is_known_to_be_of_type_dict(...) functionality. The logic for this function was duplicated in a few spots, so I moved the code to a central location, removed redundant definitions, and updated existing calls to use the single definition of the function!

Test Plan

Since this PR only modifies an existing rule, I made changes to the existing test instead of adding new ones. I made sure that SIM401 is triggered on types that are clearly dictionaries and that it's not triggered on a simple custom dictionary-like type (using a modified version of the code in the issue)

The additional changes to de-duplicate is_known_to_be_of_type_dict don't break any existing tests -- I think this should be fine since the logic remains the same (please let me know if you think otherwise, I'm excited to get feedback and work towards a good fix 🙂).

[github-actions]

ruff-ecosystem results

Linter (stable)

ℹ️ ecosystem check detected linter changes. (+0 -5 violations, +0 -0 fixes in 3 projects; 52 projects unchanged)

apache/airflow (+0 -2 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --no-fix --output-format concise --no-preview --select ALL

- providers/src/airflow/providers/databricks/operators/databricks.py:87:29: SIM401 Use `error = run_output.get("error", run_state.state_message)` instead of an `if` block
- providers/src/airflow/providers/databricks/triggers/databricks.py:107:29: SIM401 Use `error = run_output.get("error", run_state.state_message)` instead of an `if` block

binary-husky/gpt_academic (+0 -1 violations, +0 -0 fixes)

- toolbox.py:437:9: SIM401 Use `current = chatbot._cookies.get("files_to_promote", [])` instead of an `if` block

zulip/zulip (+0 -2 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --no-fix --output-format concise --no-preview --select ALL

- zerver/data_import/mattermost.py:553:9: SIM401 Use `post_team = post.get("team", team_name)` instead of an `if` block
- zproject/computed_settings.py:1186:5: SIM401 Use `path = idp_dict.get("x509cert_path", f"/etc/zulip/saml/idps/{idp_name}.crt")` instead of an `if` block

Changes by rule (1 rules affected)

code	total	+ violation	- violation	+ fix	- fix
SIM401	5	0	5	0	0

Linter (preview)

ℹ️ ecosystem check detected linter changes. (+0 -5 violations, +0 -0 fixes in 3 projects; 52 projects unchanged)

apache/airflow (+0 -2 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --no-fix --output-format concise --preview --select ALL

- providers/src/airflow/providers/databricks/operators/databricks.py:87:29: SIM401 Use `error = run_output.get("error", run_state.state_message)` instead of an `if` block
- providers/src/airflow/providers/databricks/triggers/databricks.py:107:29: SIM401 Use `error = run_output.get("error", run_state.state_message)` instead of an `if` block

binary-husky/gpt_academic (+0 -1 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --no-fix --output-format concise --preview

- toolbox.py:437:9: SIM401 Use `current = chatbot._cookies.get("files_to_promote", [])` instead of an `if` block

zulip/zulip (+0 -2 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --no-fix --output-format concise --preview --select ALL

- zerver/data_import/mattermost.py:553:9: SIM401 Use `post_team = post.get("team", team_name)` instead of an `if` block
- zproject/computed_settings.py:1186:5: SIM401 Use `path = idp_dict.get("x509cert_path", f"/etc/zulip/saml/idps/{idp_name}.crt")` instead of an `if` block

Changes by rule (1 rules affected)

code	total	+ violation	- violation	+ fix	- fix
SIM401	5	0	5	0	0

[MichaReiser]

Going through the ecosystem results. It's somewhat unfortunate that most of those were true-positives but I still think this is the right trade-off and improvements to the type inference will help to detect the false-negatives in the future.

[MichaReiser]

Thanks