feat: mock da

Author: distractedm1nd

crates/da/src/lib.rs

@@ -66,6 +66,7 @@ impl From<EpochCommitments> for (Digest, Digest) {
 
 /// `VerifiableStateTransition` is a trait wrapper around `FinalizedEpoch` that allows for mocking.
 /// The only concrete implementation of this trait is by `FinalizedEpoch`.
+#[automock]
 pub trait VerifiableStateTransition: Send {
     fn verify(
         &self,

crates/node_types/lightclient/src/lib.rs

@@ -1,2 +1,5 @@
 pub mod lightclient;
 pub use lightclient::LightClient;
+
+#[cfg(test)]
+mod tests;

crates/node_types/lightclient/src/tests/mod.rs

@@ -0,0 +1,64 @@
+use std::collections::HashMap;
+
+use anyhow::Result;
+use prism_common::digest::Digest;
+use prism_da::{
+    EpochVerificationError, MockLightDataAvailabilityLayer, MockVerifiableStateTransition,
+    VerifiableEpoch, VerifiableStateTransition,
+};
+
+macro_rules! mock_da {
+    ($(($height:expr, $($spec:tt),+)),* $(,)?) => {{
+        let mut mock_da = MockLightDataAvailabilityLayer::new();
+        mock_da.expect_get_finalized_epoch().returning(move |height| {
+            match height {
+                $(
+                    $height => {
+                        let mut transitions = vec![];
+                        $(
+                            let mut epoch = MockVerifiableStateTransition::new();
+                            mock_da!(@make_epoch epoch, $spec);
+                            transitions.push(Box::new(epoch) as Box<dyn VerifiableStateTransition>);
+                        )+
+                        Ok(transitions)
+                    }
+                )*
+                _ => Ok(vec![]),
+            }
+        });
+        mock_da
+    }};
+
+    // Success case - tuple
+    (@make_epoch $epoch:ident, ($h1:expr, $h2:expr)) => {
+        let hash1 = $h1;
+        let hash2 = $h2;
+        $epoch.expect_verify().returning(move |_, _| {
+            Ok((Digest::hash(hash1), Digest::hash(hash2)))
+        });
+    };
+
+    // Error case - Err(...)
+    (@make_epoch $epoch:ident, Err($error:expr)) => {
+        let err = $error;
+        $epoch.expect_verify().returning(move |_, _| Err(err));
+    };
+
+    // String error shorthand
+    (@make_epoch $epoch:ident, $error:literal) => {
+        let err_msg = $error;
+        $epoch.expect_verify().returning(move |_, _| {
+            Err(EpochVerificationError::ProofVerificationError(err_msg.to_string()))
+        });
+    };
+}
+
+fn setup() {
+    let mut mock_da = MockLightDataAvailabilityLayer::new();
+    mock_da![
+        (5, ("abc", "def")),
+        (6, ("ghi", "jkl"), ("xyz", "yuu")),
+        (7, ("mno", "pqr")),
+        (8, "Expected Error")
+    ];
+}