From 9e5cd23e425d83fae3a0fcd2a1fc40f058ecb0c9 Mon Sep 17 00:00:00 2001
From: teor <teor@riseup.net>
Date: Tue, 13 Oct 2020 08:52:03 +1000
Subject: [PATCH] Test difficulty is valid for all block test vectors

---
 zebra-consensus/src/block/tests.rs | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/zebra-consensus/src/block/tests.rs b/zebra-consensus/src/block/tests.rs
index 6a5afa3c5..ee0bc19ff 100644
--- a/zebra-consensus/src/block/tests.rs
+++ b/zebra-consensus/src/block/tests.rs
@@ -6,6 +6,7 @@ use super::*;
 
 use std::sync::Arc;
 
+use block::Height;
 use chrono::Utc;
 use color_eyre::eyre::{eyre, Report};
 use once_cell::sync::Lazy;
@@ -145,6 +146,32 @@ fn coinbase_is_first_for_historical_blocks() -> Result<(), Report> {
     Ok(())
 }
 
+#[test]
+fn difficulty_is_valid_for_historical_blocks() -> Result<(), Report> {
+    difficulty_is_valid_for_network(Network::Mainnet)?;
+    difficulty_is_valid_for_network(Network::Testnet)?;
+
+    Ok(())
+}
+
+fn difficulty_is_valid_for_network(network: Network) -> Result<(), Report> {
+    let block_iter = match network {
+        Network::Mainnet => zebra_test::vectors::MAINNET_BLOCKS.iter(),
+        Network::Testnet => zebra_test::vectors::TESTNET_BLOCKS.iter(),
+    };
+
+    for (&height, block) in block_iter {
+        let block = block
+            .zcash_deserialize_into::<Block>()
+            .expect("block is structurally valid");
+
+        check::difficulty_is_valid(&block.header, network, &Height(height), &block.hash())
+            .expect("the difficulty from a historical block should be valid");
+    }
+
+    Ok(())
+}
+
 #[test]
 fn equihash_is_valid_for_historical_blocks() -> Result<(), Report> {
     let block_iter = zebra_test::vectors::BLOCKS.iter();