Add a fuzzer target

fuzz/test_differential_fuzzer.py

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+import sys
+import math
+import os
+import pytest
+
+from msgpack import _cmsgpack, fallback
+
+
+def replace_nan(data, sentinel):
+    if type(data) == float and math.isnan(data):
+        return sentinel
+    if type(data) == list:
+        return [replace_nan(x, sentinel) for x in data]
+    if type(data) == dict:
+        return {k: replace_nan(v, sentinel) for k, v in data.items()}
+    return data
+
+
+def TestOneInput(data):
+    try:
+        from_extension = _cmsgpack.unpackb(data)
+    except:
+        return
+    try:
+        from_fallback = fallback.unpackb(data)
+    except:
+        return
+    sentinel = object()
+    if replace_nan(from_extension, sentinel) != replace_nan(from_fallback, sentinel):
+        raise RuntimeError(
+            f"Decoding disagreement: input: {data}, from extension: {from_extension}, from fallback: {from_fallback}"
+        )
+
+
+SCRIPT_DIR = os.path.dirname(__file__)
+CORPUS_DIR = os.path.join(SCRIPT_DIR, "test_differential_fuzzer_seed_corpus")
+if os.path.exists(CORPUS_DIR):
+    CORPUS = [
+        open(os.path.join(CORPUS_DIR, f), "rb").read() for f in os.listdir(CORPUS_DIR)
+    ]
+else:
+    # When this file is executed as a fuzz target the dirrectory
+    # test_differential_fuzzer_seed_corpus does not exist
+    CORPUS = []
+
+
+@pytest.mark.parametrize("data", CORPUS)
+def test_try_the_seed_corpus(data):
+    TestOneInput(data)
+
+
+def main():
+    import atheris
+
+    atheris.Setup(sys.argv, TestOneInput)
+    atheris.Fuzz()
+
+
+if __name__ == "__main__":
+    main()

fuzz/test_differential_fuzzer_seed_corpus/EmptyArray.bin

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fuzz/test_differential_fuzzer_seed_corpus/EmptyObject.bin

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fuzz/test_differential_fuzzer_seed_corpus/ExcessiveNesting.bin

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