Adopt ruff for linting

[simonw]

https://beta.ruff.rs/docs/

[simonw]

I tried it just now and got some interesting results.

I dropped in a ruff.toml file:

line-length = 160

Because the default line length limit of 88 was causing a lot of noisy errors.

Then run:

pip install ruff
ruff check .

Plenty of warnings about unused imports - running ruff check . --fix fixed those automatically, but I think I still need to manually review them as some might be imports which are deliberate and should be in __all__ to ensure they are visible from that module as well.

Some lines in tests are longer than even 160 chars, e.g.:

datasette/tests/test_html.py

Lines 673 to 681 in 99ba051

	expected_tds = [
	[
	'<td class="col-data"><a class="blob-download" href="/fixtures.blob?sql=select+*+from+binary_data&amp;_blob_column=data&amp;_blob_hash=f3088978da8f9aea479ffc7f631370b968d2e855eeb172bea7f6c7a04262bb6d">&lt;Binary:\xa07\xa0bytes&gt;</a></td>'
	],
	[
	'<td class="col-data"><a class="blob-download" href="/fixtures.blob?sql=select+*+from+binary_data&amp;_blob_column=data&amp;_blob_hash=b835b0483cedb86130b9a2c280880bf5fadc5318ddf8c18d0df5204d40df1724">&lt;Binary:\xa07\xa0bytes&gt;</a></td>'
	],
	['<td class="col-data">\xa0</td>'],
	]

These can have # noqa: E501 added to the end of those lines to skip the check for them.

That got it down to:

% ruff check . 
datasette/views/table.py:23:5: F811 Redefinition of unused `format_bytes` from line 19
run_tests.py:2:5: E401 Multiple imports on one line
tests/test_api.py:591:40: F811 Redefinition of unused `app_client_no_files` from line 7
tests/test_api.py:629:35: F811 Redefinition of unused `app_client_no_files` from line 7
tests/test_api.py:635:54: F811 Redefinition of unused `app_client_with_dot` from line 8
tests/test_api.py:661:25: F811 Redefinition of unused `app_client_shorter_time_limit` from line 9
tests/test_api.py:759:25: F811 Redefinition of unused `app_client_two_attached_databases_one_immutable` from line 10
tests/test_api.py:892:28: F811 Redefinition of unused `app_client_larger_cache_size` from line 11
tests/test_api.py:928:5: F811 Redefinition of unused `app_client_with_cors` from line 12
tests/test_api.py:929:5: F811 Redefinition of unused `app_client_two_attached_databases_one_immutable` from line 10
tests/test_api.py:969:38: F811 Redefinition of unused `app_client_two_attached_databases` from line 13
tests/test_api.py:976:39: F811 Redefinition of unused `app_client_conflicting_database_names` from line 14
tests/test_api.py:987:38: F811 Redefinition of unused `app_client_immutable_and_inspect_file` from line 15
tests/test_api.py:1002:24: F811 Redefinition of unused `app_client` from line 6
tests/test_csv.py:67:33: F811 Redefinition of unused `app_client_with_cors` from line 6
tests/test_csv.py:157:21: F811 Redefinition of unused `app_client_csv_max_mb_one` from line 5
tests/test_csv.py:198:20: F811 Redefinition of unused `app_client_with_trace` from line 7
tests/test_csv.py:209:53: F811 Redefinition of unused `app_client_with_trace` from line 7
tests/test_csv.py:215:53: F811 Redefinition of unused `app_client_with_trace` from line 7
tests/test_filters.py:102:11: F811 Redefinition of unused `test_through_filters_from_request` from line 81
tests/test_html.py:19:19: F811 Redefinition of unused `app_client_two_attached_databases` from line 7
tests/test_html.py:175:25: F811 Redefinition of unused `app_client_shorter_time_limit` from line 6
tests/test_html.py:469:51: F811 Redefinition of unused `app_client` from line 4
tests/test_html.py:797:26: F811 Redefinition of unused `app_client_base_url_prefix` from line 5
tests/test_html.py:840:44: F811 Redefinition of unused `app_client_base_url_prefix` from line 5
tests/test_html.py:850:51: F811 Redefinition of unused `app_client_base_url_prefix` from line 5
tests/test_pagination.py:50:43: F821 Undefined name `parse_next`
tests/test_pagination.py:82:7: F811 Redefinition of unused `KeysetPaginator` from line 36
tests/test_plugins.py:115:15: E741 Ambiguous variable name: `l`
tests/test_plugins.py:482:161: E501 Line too long (170 > 160 characters)
tests/test_plugins.py:543:29: E741 Ambiguous variable name: `l`
tests/test_plugins.py:563:161: E501 Line too long (170 > 160 characters)
tests/test_plugins.py:940:62: E741 Ambiguous variable name: `l`
tests/test_table_api.py:739:5: F811 Redefinition of unused `app_client_returned_rows_matches_page_size` from line 6
tests/test_table_api.py:1066:45: F811 Redefinition of unused `app_client_with_trace` from line 5
tests/test_table_html.py:484:29: E741 Ambiguous variable name: `l`
tests/test_table_html.py:524:29: E741 Ambiguous variable name: `l`
tests/test_table_html.py:675:161: E501 Line too long (165 > 160 characters)
tests/test_table_html.py:897:161: E501 Line too long (164 > 160 characters)
tests/test_table_html.py:902:161: E501 Line too long (164 > 160 characters)
tests/test_utils.py:141:161: E501 Line too long (176 > 160 characters)
Found 41 errors.

Those "Redefinition of unused app_client_two_attached_databases" lines are caused because of the fixtures pattern I'm using here:

datasette/tests/test_html.py

Lines 3 to 20 in 99ba051

	from .fixtures import ( # noqa
	app_client,
	app_client_base_url_prefix,
	app_client_shorter_time_limit,
	app_client_two_attached_databases,
	make_app_client,
	METADATA,
	)
	from .utils import assert_footer_links, inner_html
	import json
	import pathlib
	import pytest
	import re
	import urllib.parse
	def test_homepage(app_client_two_attached_databases):
	response = app_client_two_attached_databases.get("/")

I could fix that by getting rid of fixtures.py and moving those into conftest.py.

[simonw]

Decided to fix just those "Ambiguous variable name" ones:

ruff check . | grep E741

Then iterated through and fixed them all.