DEMO: Simple proptest that repros the bug in lightningdevkit#1935

Author: MaxFangX

lightning/Cargo.toml

@@ -51,6 +51,7 @@ core2 = { version = "0.3.0", optional = true, default-features = false }
 [dev-dependencies]
 hex = "0.4"
 regex = "1.5.6"
+proptest = "1"
 
 [dev-dependencies.bitcoin]
 version = "0.29.0"

lightning/proptest-regressions/chain/keysinterface.txt

@@ -0,0 +1,7 @@
+# Seeds for failure cases proptest has generated in the past. It is
+# automatically read and these particular cases re-run before any
+# novel cases are generated.
+#
+# It is recommended to check this file in to source control so that
+# everyone who runs the test benefits from these saved cases.
+cc 15e12e1f6dd9cfa0f0e3ae317db6c67b066f0450d694f7ffd3ca740e51524d9e # shrinks to keys_manager = , channel_value_sat = 0, params = [0, 0, 0, 0, 128, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

lightning/src/chain/keysinterface.rs

@@ -1428,3 +1428,43 @@ impl PhantomKeysManager {
 pub fn dyn_sign() {
 	let _signer: Box<dyn BaseSign>;
 }
+
+#[cfg(test)]
+mod test {
+    use std::fmt::{self, Debug};
+
+    use proptest::strategy::{BoxedStrategy, Strategy};
+    use proptest::arbitrary::{any, Arbitrary};
+    use proptest::proptest;
+
+    use super::*;
+
+    impl Debug for KeysManager {
+        fn fmt(&self, _: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+            Ok(())
+        }
+    }
+
+    impl Arbitrary for KeysManager {
+        type Parameters = ();
+        type Strategy = BoxedStrategy<Self>;
+        fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy {
+            (any::<[u8; 32]>(), any::<u64>(), any::<u32>())
+                .prop_map(|(seed, secs, nanos)| {
+                    KeysManager::new(&seed, secs, nanos)
+                })
+                .boxed()
+        }
+    }
+
+    #[test]
+    fn derive_channel_keys_doesnt_panic() {
+        proptest!(|(
+            keys_manager in any::<KeysManager>(),
+            channel_value_sat in any::<u64>(),
+            params in any::<[u8; 32]>(),
+        )| {
+            keys_manager.derive_channel_keys(channel_value_sat, &params);
+        });
+    }
+}