Add wrapper fn is_time_valid_at in zebra_consensus::block::check

This commit doesn't move the fn itself because it's tests can't
depend on `generate` code which is not exposed to other crates.

zebra-chain/src/block/header.rs

@@ -68,20 +68,8 @@ pub struct Header {
 }
 
 impl Header {
-    /// Check if `self.time` is less than or equal to
+    /// TODO Inline this function in zebra_consensus::block::check see
-    /// 2 hours in the future, according to the node's local clock (`now`).
+    /// https://github.com/ZcashFoundation/zebra/issues/1021 for more details
-    ///
-    /// This is a non-deterministic rule, as clocks vary over time, and
-    /// between different nodes.
-    ///
-    /// "In addition, a full validator MUST NOT accept blocks with nTime
-    /// more than two hours in the future according to its clock. This
-    /// is not strictly a consensus rule because it is nondeterministic,
-    /// and clock time varies between nodes. Also note that a block that
-    /// is rejected by this rule at a given point in time may later be
-    /// accepted." [§7.5][7.5]
-    ///
-    /// [7.5]: https://zips.z.cash/protocol/protocol.pdf#blockheader
     pub fn is_time_valid_at(&self, now: DateTime<Utc>) -> Result<(), Error> {
         let two_hours_in_the_future = now
             .checked_add_signed(Duration::hours(2))

zebra-chain/src/block/tests/vectors.rs

@@ -1,7 +1,4 @@
-use std::{
+use std::io::{Cursor, Write};
-    io::{Cursor, Write},
-    sync::Arc,
-};
 
 use chrono::{DateTime, Duration, LocalResult, TimeZone, Utc};
 
@@ -145,25 +142,6 @@ fn block_limits_single_tx() {
     Block::zcash_deserialize(&data[..]).expect_err("block should not deserialize");
 }
 
-#[test]
-fn time_check_past_block() {
-    // This block is also verified as part of the BlockVerifier service
-    // tests.
-    let block =
-        Arc::<Block>::zcash_deserialize(&zebra_test::vectors::BLOCK_MAINNET_415000_BYTES[..])
-            .expect("block should deserialize");
-    let now = Utc::now();
-
-    // This check is non-deterministic, but BLOCK_MAINNET_415000 is
-    // a long time in the past. So it's unlikely that the test machine
-    // will have a clock that's far enough in the past for the test to
-    // fail.
-    block
-        .header
-        .is_time_valid_at(now)
-        .expect("the header time from a mainnet block should be valid");
-}
-
 /// Test wrapper for `BlockHeader.is_time_valid_at`.
 ///
 /// Generates a block header, sets its `time` to `block_header_time`, then

zebra-consensus/src/block.rs

@@ -107,7 +107,7 @@ where
 
             // Field validity and structure checks
             let now = Utc::now();
-            block.header.is_time_valid_at(now)?;
+            check::is_time_valid_at(&block.header, now)?;
             check::is_coinbase_first(&block)?;
 
             // TODO:

zebra-consensus/src/block/check.rs

@@ -1,6 +1,7 @@
 //! Consensus check functions
 
 use super::*;
+use chrono::{DateTime, Utc};
 use zebra_chain::{
     block::{Block, Header},
     work::equihash,
@@ -29,6 +30,25 @@ pub fn is_coinbase_first(block: &Block) -> Result<(), Error> {
     Ok(())
 }
 
+/// Returns true if the header is valid based on its `EquihashSolution`
 pub fn is_equihash_solution_valid(header: &Header) -> Result<(), equihash::Error> {
     header.solution.check(&header)
 }
+
+/// Check if `header.time` is less than or equal to
+/// 2 hours in the future, according to the node's local clock (`now`).
+///
+/// This is a non-deterministic rule, as clocks vary over time, and
+/// between different nodes.
+///
+/// "In addition, a full validator MUST NOT accept blocks with nTime
+/// more than two hours in the future according to its clock. This
+/// is not strictly a consensus rule because it is nondeterministic,
+/// and clock time varies between nodes. Also note that a block that
+/// is rejected by this rule at a given point in time may later be
+/// accepted." [§7.5][7.5]
+///
+/// [7.5]: https://zips.z.cash/protocol/protocol.pdf#blockheader
+pub fn is_time_valid_at(header: &Header, now: DateTime<Utc>) -> Result<(), Error> {
+    header.is_time_valid_at(now)
+}

zebra-consensus/src/block/tests.rs

@@ -2,6 +2,8 @@
 
 use super::*;
 
+use std::sync::Arc;
+
 use chrono::Utc;
 use color_eyre::eyre::{eyre, Report};
 use once_cell::sync::Lazy;
@@ -121,3 +123,20 @@ async fn check_transcripts() -> Result<(), Report> {
     }
     Ok(())
 }
+
+#[test]
+fn time_check_past_block() {
+    // This block is also verified as part of the BlockVerifier service
+    // tests.
+    let block =
+        Arc::<Block>::zcash_deserialize(&zebra_test::vectors::BLOCK_MAINNET_415000_BYTES[..])
+            .expect("block should deserialize");
+    let now = Utc::now();
+
+    // This check is non-deterministic, but BLOCK_MAINNET_415000 is
+    // a long time in the past. So it's unlikely that the test machine
+    // will have a clock that's far enough in the past for the test to
+    // fail.
+    check::is_time_valid_at(&block.header, now)
+        .expect("the header time from a mainnet block should be valid");
+}