Set format_checker when checking schemas

This allows the `check_schema` call to succeed when it requires that
the regex implementation is regress. Patterns which can compile as
regress patterns are thereby supported.

Add initial acceptance tests for regress 'pattern' support, which
revealed this issue.

src/check_jsonschema/schema_loader/main.py

@@ -173,7 +173,7 @@ def _get_validator(
         if self.validator_class is None:
             # get the correct validator class and check the schema under its metaschema
             validator_cls = jsonschema.validators.validator_for(schema)
-            validator_cls.check_schema(schema)
+            validator_cls.check_schema(schema, format_checker=format_checker)
         else:
             # for a user-provided validator class, don't check_schema
             # on the grounds that it might *not* be valid but the user wants to use

tests/acceptance/test_example_files.py

@@ -63,7 +63,7 @@ def test_hook_positive_examples(case_name, run_line):
 
     hook_id = POSITIVE_HOOK_CASES[case_name]
     ret = run_line(HOOK_CONFIG[hook_id] + [rcase.path] + rcase.add_args)
-    assert ret.exit_code == 0, _format_cli_result(rcase, ret)
+    assert ret.exit_code == 0, _format_cli_result(ret, rcase)
 
 
 @pytest.mark.parametrize("case_name", NEGATIVE_HOOK_CASES.keys())
@@ -72,7 +72,7 @@ def test_hook_negative_examples(case_name, run_line):
 
     hook_id = NEGATIVE_HOOK_CASES[case_name]
     ret = run_line(HOOK_CONFIG[hook_id] + [rcase.path] + rcase.add_args)
-    assert ret.exit_code == 1, _format_cli_result(rcase, ret)
+    assert ret.exit_code == 1, _format_cli_result(ret, rcase)
 
 
 @pytest.mark.parametrize("case_name", _get_explicit_cases("positive"))
@@ -102,7 +102,37 @@ def test_explicit_positive_examples(case_name, run_line):
             str(instance),
         ]
     )
-    assert ret.exit_code == 0
+    assert ret.exit_code == 0, _format_cli_result(ret)
+
+
+@pytest.mark.parametrize("case_name", _get_explicit_cases("negative"))
+def test_explicit_negative_examples(case_name, run_line):
+    _check_file_format_skip(case_name)
+    casedir = EXAMPLE_EXPLICIT_FILES / "negative" / case_name
+
+    instance = casedir / "instance.json"
+    if not instance.exists():
+        instance = casedir / "instance.yaml"
+    if not instance.exists():
+        instance = casedir / "instance.toml"
+    if not instance.exists():
+        raise Exception("could not find an instance file for test case")
+
+    schema = casedir / "schema.json"
+    if not schema.exists():
+        schema = casedir / "schema.yaml"
+    if not schema.exists():
+        raise Exception("could not find a schema file for test case")
+
+    ret = run_line(
+        [
+            "check-jsonschema",
+            "--schemafile",
+            str(schema),
+            str(instance),
+        ]
+    )
+    assert ret.exit_code == 1, _format_cli_result(ret)
 
 
 def _check_file_format_skip(case_name):
@@ -166,10 +196,12 @@ def _package_is_installed(pkg: str) -> bool:
     return True
 
 
-def _format_cli_result(rcase: ResolvedCase, result) -> str:
+def _format_cli_result(result, rcase: ResolvedCase | None = None) -> str:
+    prefix = ""
+    if rcase is not None:
+        prefix = f"config.add_args={rcase.add_args}\n"
     return (
-        "\n"
-        f"config.add_args={rcase.add_args}\n"
+        f"\n{prefix}"
         f"{result.exit_code=}\n"
         f"result.stdout={result.output}\n"
         f"{result.stderr=}"

tests/example-files/explicit-schema/negative/unicode_pattern/instance.json

@@ -0,0 +1,4 @@
+{
+  "key": "foo 1",
+  "value": "bar 2"
+}

tests/example-files/explicit-schema/negative/unicode_pattern/schema.json

@@ -0,0 +1,20 @@
+{
+  "additionalProperties": false,
+  "properties": {
+    "key": {
+      "description": "some key",
+      "maxLength": 128,
+      "minLength": 1,
+      "pattern": "^\\p{L}\\p{Z}\\p{N}$",
+      "type": "string"
+    },
+    "value": {
+      "description": "some value",
+      "maxLength": 256,
+      "minLength": 0,
+      "pattern": "^\\p{L}\\p{Z}\\p{N}$",
+      "type": "string"
+    }
+  },
+  "type": "object"
+}

tests/example-files/explicit-schema/positive/unicode_pattern/instance.json

@@ -0,0 +1,4 @@
+{
+  "key": "a 1",
+  "value": "b 2"
+}

tests/example-files/explicit-schema/positive/unicode_pattern/schema.json

@@ -0,0 +1,20 @@
+{
+  "additionalProperties": false,
+  "properties": {
+    "key": {
+      "description": "some key",
+      "maxLength": 128,
+      "minLength": 1,
+      "pattern": "^\\p{L}\\p{Z}\\p{N}$",
+      "type": "string"
+    },
+    "value": {
+      "description": "some value",
+      "maxLength": 256,
+      "minLength": 0,
+      "pattern": "^\\p{L}\\p{Z}\\p{N}$",
+      "type": "string"
+    }
+  },
+  "type": "object"
+}