skip tests whose optional dependency is not installed

With pywikidiff2 and mediawiki-utilities no longer installed by default,
the tests covering --diff, -p wikidiff2, and -p legacy cannot run on a
base install. Mark them so a base install reports skips rather than
failures, and keep the markers in wikiq_test_utils.py so all three test
modules share one definition of what each feature needs.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
(cherry picked from commit 59d5a9d46a04320bad5d81e0edf5ecd11f9c2a9b)

test/Wikiq_Unit_Test.py

@@ -23,6 +23,8 @@ from wikiq_test_utils import (
     TWINPEAKS,
     WIKIQ,
     WikiqTester,
+    requires_mediawiki_utilities,
+    requires_pywikidiff2,
 )
 
 
@@ -205,6 +207,7 @@ def test_collapse_user():
     baseline = pd.read_table(tester.baseline_file)
     assert_frame_equal(test, baseline, check_like=True)
 
+@requires_pywikidiff2
 def test_pwr_wikidiff2():
     tester = WikiqTester(SAILORMOON, "persistence_wikidiff2", in_compression="7z")
 
@@ -229,6 +232,7 @@ def test_pwr_segment():
     baseline = pd.read_table(tester.baseline_file)
     assert_frame_equal(test, baseline, check_like=True)
 
+@requires_mediawiki_utilities
 def test_pwr_legacy():
     tester = WikiqTester(SAILORMOON, "persistence_legacy", in_compression="7z")
 
@@ -255,6 +259,7 @@ def test_pwr():
     test = test.reindex(columns=sorted(test.columns))
     assert_frame_equal(test, baseline, check_like=True)
 
+@requires_pywikidiff2
 def test_diff():
     tester = WikiqTester(SAILORMOON, "diff", in_compression="7z", out_format='jsonl')
 
@@ -268,6 +273,7 @@ def test_diff():
     assert "diff_timeout" in test.columns, "diff_timeout column should exist"
     assert len(test) > 0, "Should have output rows"
 
+@requires_pywikidiff2
 def test_diff_plus_pwr():
     tester = WikiqTester(SAILORMOON, "diff_pwr", in_compression="7z", out_format='jsonl')
 
@@ -281,6 +287,7 @@ def test_diff_plus_pwr():
     assert "token_revs" in test.columns, "token_revs column should exist"
     assert len(test) > 0, "Should have output rows"
 
+@requires_pywikidiff2
 def test_text():
     tester = WikiqTester(SAILORMOON, "text", in_compression="7z", out_format='jsonl')