From cff07e787a94d97ca150ce848675c0ab9fe28783 Mon Sep 17 00:00:00 2001
From: sumanjeet0012 <sumanjeet0012@gmail.com>
Date: Mon, 13 Jul 2026 22:48:07 +0530
Subject: [PATCH 1/3] Add fuzz testing

---
 newsfragments/72.feature.rst |  1 +
 tests/test_fuzz.py           | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+)
 create mode 100644 newsfragments/72.feature.rst
 create mode 100644 tests/test_fuzz.py

diff --git a/newsfragments/72.feature.rst b/newsfragments/72.feature.rst
new file mode 100644
index 0000000..70a2d7f
--- /dev/null
+++ b/newsfragments/72.feature.rst
@@ -0,0 +1 @@
+Add property-based fuzz testing using `hypothesis` to ensure CID parsing and encoding are robust against arbitrary input and do not crash.
diff --git a/tests/test_fuzz.py b/tests/test_fuzz.py
new file mode 100644
index 0000000..a0e23aa
--- /dev/null
+++ b/tests/test_fuzz.py
@@ -0,0 +1,24 @@
+import pytest
+from hypothesis import given, strategies as st, settings
+from cid import make_cid, CIDv1, CIDv0
+
+@given(st.binary(max_size=200))
+@settings(max_examples=1000)
+def test_from_bytes_never_crashes(data):
+    """from_bytes should raise ValueError, KeyError, or TypeError, not crash."""
+    try:
+        make_cid(data)
+    except (ValueError, KeyError, TypeError):
+        pass  # Any exception is fine, just no crashes
+
+@given(st.binary(min_size=34, max_size=100))
+@settings(max_examples=500)
+def test_cid_roundtrip_never_crashes(data):
+    """CID encode/decode should never crash."""
+    try:
+        cid = make_cid(data)
+        _ = cid.encode()
+        _ = str(cid)
+        _ = cid.prefix()
+    except (ValueError, KeyError, TypeError):
+        pass

From 89618f1bc28f65b1d9c78ab9e71f1e24a92e3f1e Mon Sep 17 00:00:00 2001
From: sumanjeet0012 <sumanjeet0012@gmail.com>
Date: Mon, 13 Jul 2026 22:53:23 +0530
Subject: [PATCH 2/3] Fix lint errors in test_fuzz.py

---
 tests/test_fuzz.py | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/tests/test_fuzz.py b/tests/test_fuzz.py
index a0e23aa..a10c650 100644
--- a/tests/test_fuzz.py
+++ b/tests/test_fuzz.py
@@ -1,6 +1,11 @@
-import pytest
-from hypothesis import given, strategies as st, settings
-from cid import make_cid, CIDv1, CIDv0
+from hypothesis import (
+    given,
+    settings,
+    strategies as st,
+)
+
+from cid import make_cid
+
 
 @given(st.binary(max_size=200))
 @settings(max_examples=1000)

From b69adbe5230f38edd86e8bc94e5f41c07dc6b977 Mon Sep 17 00:00:00 2001
From: sumanjeet0012 <sumanjeet0012@gmail.com>
Date: Mon, 13 Jul 2026 22:55:49 +0530
Subject: [PATCH 3/3] Fix formatting issues

---
 tests/test_fuzz.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/test_fuzz.py b/tests/test_fuzz.py
index a10c650..a3a5983 100644
--- a/tests/test_fuzz.py
+++ b/tests/test_fuzz.py
@@ -16,6 +16,7 @@ def test_from_bytes_never_crashes(data):
     except (ValueError, KeyError, TypeError):
         pass  # Any exception is fine, just no crashes
 
+
 @given(st.binary(min_size=34, max_size=100))
 @settings(max_examples=500)
 def test_cid_roundtrip_never_crashes(data):