From 2d2da001b9801d2fb7b159e74e15cf1eee9b6ef7 Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Thu, 6 Dec 2018 19:50:33 +1100
Subject: [PATCH] Implement tests for attestation validation

---
 .../src/validate_for_block.rs                 | 119 +++++++++++++++++-
 1 file changed, 117 insertions(+), 2 deletions(-)

diff --git a/beacon_chain/attestation_validation/src/validate_for_block.rs b/beacon_chain/attestation_validation/src/validate_for_block.rs
index 0094f5c59..b0e6d5d60 100644
--- a/beacon_chain/attestation_validation/src/validate_for_block.rs
+++ b/beacon_chain/attestation_validation/src/validate_for_block.rs
@@ -1,7 +1,7 @@
 use super::{Error, Invalid, Outcome};
 
 /// Check that an attestation is valid to be included in some block.
-pub fn validate_attestation_for_block<T>(
+pub fn validate_attestation_for_block(
     attestation_slot: u64,
     block_slot: u64,
     parent_block_slot: u64,
@@ -16,7 +16,9 @@ pub fn validate_attestation_for_block<T>(
      * block it is contained in.
      */
     verify_or!(
-        attestation_slot <= block_slot.saturating_sub(min_attestation_inclusion_delay),
+        // TODO: this differs from the spec as it does not handle underflows correctly.
+        // https://github.com/sigp/lighthouse/issues/95
+        attestation_slot < block_slot.saturating_sub(min_attestation_inclusion_delay - 1),
         reject!(Invalid::AttestationTooRecent)
     );
 
@@ -31,3 +33,116 @@ pub fn validate_attestation_for_block<T>(
 
     accept!()
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_inclusion_delay_minimal() {
+        let parent_block_slot = 99;
+        let min_attestation_inclusion_delay = 10;
+        let epoch_length = 20;
+        let block_slot = 100;
+        let attestation_slot = block_slot - min_attestation_inclusion_delay;
+
+        let outcome = validate_attestation_for_block(
+            attestation_slot,
+            block_slot,
+            parent_block_slot,
+            min_attestation_inclusion_delay,
+            epoch_length,
+        );
+        assert_eq!(outcome, Ok(Outcome::Valid));
+    }
+
+    #[test]
+    fn test_inclusion_delay_maximal() {
+        let parent_block_slot = 99;
+        let min_attestation_inclusion_delay = 10;
+        let epoch_length = 20;
+        let block_slot = 100;
+        let attestation_slot = block_slot - epoch_length;
+
+        let outcome = validate_attestation_for_block(
+            attestation_slot,
+            block_slot,
+            parent_block_slot,
+            min_attestation_inclusion_delay,
+            epoch_length,
+        );
+        assert_eq!(outcome, Ok(Outcome::Valid));
+    }
+
+    #[test]
+    fn test_inclusion_delay_insufficient() {
+        let parent_block_slot = 99;
+        let min_attestation_inclusion_delay = 10;
+        let epoch_length = 20;
+        let block_slot = 100;
+        let attestation_slot = block_slot - (min_attestation_inclusion_delay - 1);
+
+        let outcome = validate_attestation_for_block(
+            attestation_slot,
+            block_slot,
+            parent_block_slot,
+            min_attestation_inclusion_delay,
+            epoch_length,
+        );
+        assert_eq!(outcome, Ok(Outcome::Invalid(Invalid::AttestationTooRecent)));
+    }
+
+    #[test]
+    fn test_inclusion_delay_first_possible_slot() {
+        let min_attestation_inclusion_delay = 10;
+        let epoch_length = 20;
+        let block_slot = min_attestation_inclusion_delay;
+        let attestation_slot = 0;
+        let parent_block_slot = block_slot - 1;
+
+        let outcome = validate_attestation_for_block(
+            attestation_slot,
+            block_slot,
+            parent_block_slot,
+            min_attestation_inclusion_delay,
+            epoch_length,
+        );
+        assert_eq!(outcome, Ok(Outcome::Valid));
+    }
+
+    #[test]
+    fn test_inclusion_delay_saturation_non_zero_slot() {
+        let min_attestation_inclusion_delay = 10;
+        let epoch_length = 20;
+        let block_slot = min_attestation_inclusion_delay - 1;
+        let parent_block_slot = block_slot - 1;
+        let attestation_slot = 0;
+
+        let outcome = validate_attestation_for_block(
+            attestation_slot,
+            block_slot,
+            parent_block_slot,
+            min_attestation_inclusion_delay,
+            epoch_length,
+        );
+        assert_eq!(outcome, Ok(Outcome::Invalid(Invalid::AttestationTooRecent)));
+    }
+
+    #[test]
+    fn test_inclusion_delay_saturation_zero_slot() {
+        let min_attestation_inclusion_delay = 10;
+        let epoch_length = 20;
+        let block_slot = min_attestation_inclusion_delay - 1;
+        let parent_block_slot = block_slot - 1;
+        let attestation_slot = 0;
+
+        let outcome = validate_attestation_for_block(
+            attestation_slot,
+            block_slot,
+            parent_block_slot,
+            min_attestation_inclusion_delay,
+            epoch_length,
+        );
+        assert_eq!(outcome, Ok(Outcome::Invalid(Invalid::AttestationTooRecent)));
+    }
+}