More strict style, now via bugbear.

The unevaluated* validators will definitely need rewriting,
what they do right now is completely incorrect (which bugbear
points out at least, though poking at them trivially also does).

9 files changed, 29 insertions, 26 deletions

diff --git a/jsonschema/_format.py b/jsonschema/_format.py
index d99c717..db4c2eb 100644
--- a/jsonschema/_format.py
+++ b/jsonschema/_format.py
@@ -402,8 +402,8 @@ else:
     @_checks_drafts(draft3="color", raises=(ValueError, TypeError))
     def is_css21_color(instance):
         if (
-            not isinstance(instance, str) or
-            instance.lower() in CSS21_NAMES_TO_HEX
+            not isinstance(instance, str)
+            or instance.lower() in CSS21_NAMES_TO_HEX
         ):
             return True
         return is_css_color_code(instance)
@@ -450,7 +450,7 @@ else:
         for i, character in enumerate(instance):
             if character.isdigit():
                 # digits with a leading "0" are not allowed
-                if i > 0 and int(instance[i-1]) == 0:
+                if i > 0 and int(instance[i - 1]) == 0:
                     return False
 
                 non_negative_integer.append(character)
diff --git a/jsonschema/_types.py b/jsonschema/_types.py
index 2f6196c..5e3aa27 100644
--- a/jsonschema/_types.py
+++ b/jsonschema/_types.py
@@ -180,8 +180,8 @@ draft4_type_checker = draft3_type_checker.remove("any")
 draft6_type_checker = draft4_type_checker.redefine(
     "integer",
     lambda checker, instance: (
-        is_integer(checker, instance) or
-        isinstance(instance, float) and instance.is_integer()
+        is_integer(checker, instance)
+        or isinstance(instance, float) and instance.is_integer()
     ),
 )
 draft7_type_checker = draft6_type_checker
diff --git a/jsonschema/_utils.py b/jsonschema/_utils.py
index 54f9c22..f9fdd2c 100644
--- a/jsonschema/_utils.py
+++ b/jsonschema/_utils.py
@@ -332,7 +332,7 @@ def find_evaluated_property_keys_by_schema(validator, instance, schema):
 
     if "patternProperties" in schema:
         for property, value in instance.items():
-            for pattern, subschema in schema["patternProperties"].items():
+            for pattern, _ in schema["patternProperties"].items():
                 if re.search(pattern, property) and validator.is_valid(
                         {property: value}, schema["patternProperties"],
                 ):
diff --git a/jsonschema/_validators.py b/jsonschema/_validators.py
index 2784c09..11bd2a4 100644
--- a/jsonschema/_validators.py
+++ b/jsonschema/_validators.py
@@ -92,8 +92,8 @@ def items(validator, items, instance, schema):
 
 def additionalItems(validator, aI, instance, schema):
     if (
-        not validator.is_type(instance, "array") or
-        validator.is_type(schema.get("items", {}), "object")
+        not validator.is_type(instance, "array")
+        or validator.is_type(schema.get("items", {}), "object")
     ):
         return
 
@@ -225,17 +225,17 @@ def maxItems(validator, mI, instance, schema):
 
 def uniqueItems(validator, uI, instance, schema):
     if (
-        uI and
-        validator.is_type(instance, "array") and
-        not uniq(instance)
+        uI
+        and validator.is_type(instance, "array")
+        and not uniq(instance)
     ):
         yield ValidationError(f"{instance!r} has non-unique elements")
 
 
 def pattern(validator, patrn, instance, schema):
     if (
-        validator.is_type(instance, "string") and
-        not re.search(patrn, instance)
+        validator.is_type(instance, "string")
+        and not re.search(patrn, instance)
     ):
         yield ValidationError(f"{instance!r} does not match {patrn!r}")
 
@@ -435,14 +435,10 @@ def unevaluatedItems(validator, unevaluatedItems, instance, schema):
     evaluated_item_indexes = find_evaluated_item_indexes_by_schema(
         validator, instance, schema,
     )
-    unevaluated_items = []
-    for k, v in enumerate(instance):
-        if k not in evaluated_item_indexes:
-            for error in validator.descend(
-                v, unevaluatedItems, schema_path="unevaluatedItems",
-            ):
-                unevaluated_items.append(v)
-
+    unevaluated_items = [
+        item for index, item in enumerate(instance)
+        if index not in evaluated_item_indexes
+    ]
     if unevaluated_items:
         error = "Unevaluated items are not allowed (%s %s unexpected)"
         yield ValidationError(error % extras_msg(unevaluated_items))
@@ -453,9 +449,9 @@ def unevaluatedProperties(validator, unevaluatedProperties, instance, schema):
         validator, instance, schema,
     )
     unevaluated_property_keys = []
-    for property, subschema in instance.items():
+    for property in instance:
         if property not in evaluated_property_keys:
-            for error in validator.descend(
+            for _ in validator.descend(
                 instance[property],
                 unevaluatedProperties,
                 path=property,
diff --git a/jsonschema/cli.py b/jsonschema/cli.py
index cfad6d1..1d7c650 100644
--- a/jsonschema/cli.py
+++ b/jsonschema/cli.py
@@ -40,7 +40,7 @@ class _Outputter(object):
     def load(self, path):
         try:
             file = open(path)
-        except (IOError, OSError) as error:
+        except OSError as error:
             if error.errno != errno.ENOENT:
                 raise
             self.filenotfound_error(path=path, exc_info=sys.exc_info())
diff --git a/jsonschema/tests/test_cli.py b/jsonschema/tests/test_cli.py
index ce2d298..1a23ea6 100644
--- a/jsonschema/tests/test_cli.py
+++ b/jsonschema/tests/test_cli.py
@@ -10,6 +10,8 @@ import subprocess
 import sys
 import tempfile
 
+from pyrsistent import m
+
 from jsonschema import Draft4Validator, Draft202012Validator, __version__, cli
 from jsonschema.exceptions import (
     RefResolutionError,
@@ -59,7 +61,7 @@ def _message_for(non_json):
 
 class TestCLI(TestCase):
     def run_cli(
-        self, argv, files={}, stdin=StringIO(), exit_code=0, **override,
+        self, argv, files=m(), stdin=StringIO(), exit_code=0, **override,
     ):
         arguments = cli.parse_args(argv)
         arguments.update(override)
diff --git a/jsonschema/validators.py b/jsonschema/validators.py
index 371c6f1..3d5e861 100644
--- a/jsonschema/validators.py
+++ b/jsonschema/validators.py
@@ -719,7 +719,7 @@ class RefResolver(object):
             if key in schema:
                 results.append(schema)
 
-            for k, v in schema.items():
+            for v in schema.values():
                 if isinstance(v, dict):
                     results += self._finditem(v, key)
 
diff --git a/setup.cfg b/setup.cfg
index 1d002e3..b8f6659 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -65,6 +65,10 @@ inline-quotes = "
 exclude =
     jsonschema/__init__.py
     jsonschema/_reflect.py
+ignore =
+    B008,  # Barring function calls in default args. Ha, no.
+    B306,  # See https://github.com/PyCQA/flake8-bugbear/issues/131
+    W503,  # (flake8 default) old PEP8 boolean operator line breaks
 
 [pydocstyle]
 match = (?!(test_|_|compat|cli)).*\.py  # see PyCQA/pydocstyle#323
diff --git a/tox.ini b/tox.ini
index a0cf3f1..71c7633 100644
--- a/tox.ini
+++ b/tox.ini
@@ -83,6 +83,7 @@ commands = {envbindir}/detect-secrets scan {toxinidir}
 [testenv:style]
 deps =
     flake8
+    flake8-bugbear
     flake8-commas
     flake8-quotes
     flake8-broken-line