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')
 

test/test_resume.py

@@ -15,6 +15,7 @@ from wikiq_test_utils import (
     TEST_OUTPUT_DIR,
     WIKIQ,
     WikiqTester,
+    requires_pywikidiff2,
 )
 
 
@@ -65,6 +66,7 @@ def test_resume():
     assert_frame_equal(df_full, df_resumed)
 
 
+@requires_pywikidiff2
 def test_resume_with_diff():
     """Test that --resume correctly computes diff values after resume.
 
@@ -305,6 +307,7 @@ def test_resume_data_equivalence():
     assert_frame_equal(df_full, df_resumed)
 
 
+@requires_pywikidiff2
 def test_resume_with_persistence():
     """Test that --resume correctly handles persistence state after resume.
 
@@ -403,6 +406,7 @@ def test_resume_corrupted_jsonl_last_line():
     assert_frame_equal(df_full, df_resumed)
 
 
+@requires_pywikidiff2
 def test_resume_diff_persistence_combined():
     """Test that --resume correctly handles both diff and persistence state together.
 
@@ -448,6 +452,7 @@ def test_resume_diff_persistence_combined():
     assert_frame_equal(df_full, df_resumed)
 
 
+@requires_pywikidiff2
 def test_resume_mid_page():
     """Test resume from the middle of a page with many revisions.
 
@@ -501,6 +506,7 @@ def test_resume_mid_page():
     assert_frame_equal(df_full, df_resumed)
 
 
+@requires_pywikidiff2
 def test_resume_page_boundary():
     """Test resume at the exact start of a new page.
 

test/test_wiki_diff_matcher.py

@@ -7,6 +7,10 @@ from typing import List
 from deltas import Delete, Equal, Insert, wikitext_split
 from mwpersistence import Token
 from wikiq.wiki_diff_matcher import WikiDiffMatcher
+from wikiq_test_utils import requires_pywikidiff2
+
+# every test here drives wikidiff2 directly
+pytestmark = requires_pywikidiff2
 
 def _replace_whitespace(match):
     if match.group(1):  # If spaces matched (e.g., '  ')

test/wikiq_test_utils.py

@@ -1,8 +1,27 @@
+import importlib.util
 import os
 import shutil
 import subprocess
 from typing import Final, Union
 
+import pytest
+
+
+def _installed(module: str) -> bool:
+    return importlib.util.find_spec(module) is not None
+
+
+# wikiq's two optional dependencies. Tests exercising --diff, -p wikidiff2, or
+# -p legacy cannot run on a base install, so they skip rather than fail.
+requires_pywikidiff2 = pytest.mark.skipif(
+    not _installed("pywikidiff2"),
+    reason="needs the optional pywikidiff2 extension (--diff, -p wikidiff2)",
+)
+requires_mediawiki_utilities = pytest.mark.skipif(
+    not _installed("mw"),
+    reason="needs the optional mediawiki-utilities package (-p legacy)",
+)
+
 TEST_DIR: Final[str] = os.path.dirname(os.path.realpath(__file__))
 WIKIQ: Final[str] = os.path.join(os.path.join(TEST_DIR, ".."), "src/wikiq/__init__.py")
 TEST_OUTPUT_DIR: Final[str] = os.path.join(TEST_DIR, "test_output")