Add deterministic wildcard loading regression coverage

Require a good file after a broken file in the #1209 regression, independent
of filesystem traversal order. Check that the warning names the file and
parser error.

Exercise wildcard_load in eager and on-demand modes for built-in and custom
folders, including malformed YAML, binary data, read failures and empty YAML.
Verify normal wildcard expansion and preserve direct and lazy loader errors.

The scan-aborting mutation fails both regression cases; all 98 standalone
checks pass with the original PR implementation. This follow-up changes tests
only and is intended to be applied after #1209 is merged.

tests/wildcards/test_wildcard_encoding_strict.py

@@ -1,6 +1,7 @@
 """Strict UTF-8 wildcard decoding checks against the fixture ground truth."""
 import logging
 import os
+from pathlib import Path
 import sys
 import tempfile
 
@@ -203,15 +204,28 @@ def test_decoding_across_loaders(tmp_path, monkeypatch, caplog, encoding, file_t
         assert not caplog.records
 
 
+@pytest.fixture
+def wildcard_loading(monkeypatch):
+    for name in ("wildcard_dict", "loaded_wildcards", "available_wildcards"):
+        monkeypatch.setattr(wc, name, {})
+    monkeypatch.setattr(wc, "_on_demand_mode", False)
+    walk = wc.os.walk
+
+    def ordered_walk(*args, **kwargs):
+        for root, directories, files in walk(*args, **kwargs):
+            # The broken file must precede a good file, regardless of filesystem order.
+            yield root, directories, sorted(files)
+
+    monkeypatch.setattr(wc.os, "walk", ordered_walk)
+
+
 @pytest.mark.parametrize("on_demand", [False, True])
-def test_bad_file_is_skipped_and_named(tmp_path, monkeypatch, caplog, on_demand):
+def test_bad_file_is_skipped_and_named(tmp_path, wildcard_loading, caplog, on_demand):
     (tmp_path / "a_good.txt").write_text("red\nblue\n", encoding="utf-8")
     bad = tmp_path / "b_broken.yaml"
     bad.write_text("colors: [unclosed\n", encoding="utf-8")
     (tmp_path / "c_empty.yaml").write_text("", encoding="utf-8")
     (tmp_path / "d_good.yaml").write_text("shapes:\n  - circle\n", encoding="utf-8")
-    monkeypatch.setattr(wc, "wildcard_dict", {})
-    monkeypatch.setattr(wc, "loaded_wildcards", {})
 
     with caplog.at_level(logging.WARNING):
         wc.read_wildcard_dict(tmp_path, on_demand=on_demand)
@@ -220,6 +234,56 @@ def test_bad_file_is_skipped_and_named(tmp_path, monkeypatch, caplog, on_demand)
     assert list(wc.wildcard_dict["shapes"]) == ["circle"]
     assert len(caplog.records) == 1
     assert str(bad) in caplog.text
+    assert "ParserError" in caplog.text
+
+
+@pytest.mark.parametrize("on_demand", [False, True], ids=["eager", "on_demand"])
+@pytest.mark.parametrize("bad_directory", ["builtin", "custom"])
+@pytest.mark.parametrize("contents", [b"colors: [unclosed\n", b"\x00\x05\x16\x07MacOS\x00", None],
+                         ids=["syntax", "binary", "read_error"])
+def test_wildcard_load_continues_after_bad_file(tmp_path, wildcard_loading, monkeypatch, caplog,
+                                              on_demand, bad_directory, contents):
+    builtin, custom = tmp_path / "builtin", tmp_path / "custom"
+    for label, directory in (("builtin", builtin), ("custom", custom)):
+        directory.mkdir()
+        (directory / f"a_{label}.txt").write_text(f"{label}-before\n", encoding="utf-8")
+        (directory / "c_empty.yaml").write_text("", encoding="utf-8")
+        (directory / "d_after.yml").write_text(f"{label}_after: [{label}-after]\n", encoding="utf-8")
+    bad = tmp_path / bad_directory / "b_bad.yaml"
+    bad.write_bytes(contents if contents is not None else b"unreadable: [value]\n")
+    if contents is None:
+        read_text = wc._read_wildcard_text
+
+        def unreadable(path):
+            if Path(path) == bad:
+                raise OSError("wildcard fixture is unreadable")
+            return read_text(path)
+
+        monkeypatch.setattr(wc, "_read_wildcard_text", unreadable)
+    monkeypatch.setattr(wc, "wildcards_path", str(builtin))
+    monkeypatch.setattr(wc.config, "get_config", lambda: {
+        "custom_wildcards": str(custom), "wildcard_cache_limit_mb": 0 if on_demand else 50})
+
+    with caplog.at_level(logging.WARNING):
+        wc.wildcard_load()
+
+    assert wc.is_on_demand_mode() is on_demand
+    assert wc.process("__a_builtin__ __builtin_after__ __a_custom__ __custom_after__", seed=7) == (
+        "builtin-before builtin-after custom-before custom-after")
+    assert len(caplog.records) == 1
+    assert str(bad) in caplog.text
+
+
+@pytest.mark.parametrize("lazy", [False, True], ids=["direct", "lazy"])
+@pytest.mark.parametrize("contents", [b"colors: [unclosed\n", b"\x00\x05\x16\x07MacOS\x00"], ids=["syntax", "binary"])
+def test_single_file_loader_still_raises(tmp_path, lazy, contents):
+    bad = tmp_path / "bad.yaml"
+    bad.write_bytes(contents)
+    with pytest.raises(yaml.YAMLError):
+        if lazy:
+            wc.LazyWildcardLoader(bad, "yaml").get_data()
+        else:
+            wc.load_yaml_wildcard(bad)
 
 
 def test_invalid_yaml_is_not_redecoded_as_latin1(tmp_path, caplog):