Report duplicate keys in check_json
Raise ValueError and return 1 if json contains duplicate keys
diff --git a/pre_commit_hooks/check_json.py b/pre_commit_hooks/check_json.py
index 6026270..db589d0 100644
--- a/pre_commit_hooks/check_json.py
+++ b/pre_commit_hooks/check_json.py
@@ -1,7 +1,23 @@
import argparse
import json
+from typing import Any
+from typing import Dict
+from typing import List
from typing import Optional
from typing import Sequence
+from typing import Tuple
+
+
+def raise_duplicate_keys(
+ ordered_pairs: List[Tuple[str, Any]],
+) -> Dict[str, Any]:
+ d = {}
+ for key, val in ordered_pairs:
+ if key in d:
+ raise ValueError(f'Duplicate key: {key}')
+ else:
+ d[key] = val
+ return d
def main(argv: Optional[Sequence[str]] = None) -> int:
@@ -13,7 +29,7 @@
for filename in args.filenames:
with open(filename, 'rb') as f:
try:
- json.load(f)
+ json.load(f, object_pairs_hook=raise_duplicate_keys)
except ValueError as exc:
print(f'{filename}: Failed to json decode ({exc})')
retval = 1
diff --git a/testing/resources/duplicate_key_json.json b/testing/resources/duplicate_key_json.json
new file mode 100644
index 0000000..8a43262
--- /dev/null
+++ b/testing/resources/duplicate_key_json.json
@@ -0,0 +1,4 @@
+{
+ "hello": "world",
+ "hello": "planet"
+}
diff --git a/tests/check_json_test.py b/tests/check_json_test.py
index c63dc4c..e010faa 100644
--- a/tests/check_json_test.py
+++ b/tests/check_json_test.py
@@ -9,6 +9,7 @@
('bad_json.notjson', 1),
('bad_json_latin1.nonjson', 1),
('ok_json.json', 0),
+ ('duplicate_key_json.json', 1),
),
)
def test_main(capsys, filename, expected_retval):
