configuration: validation_upgrade_delay consistency

Closes #4248

Impose additional constraint on configuration consistency:
`validation_upgrade_delay` should not be less than or equal to 1.

See the original issue for more details.

runtime/parachains/src/configuration.rs

@@ -219,7 +219,7 @@ impl<BlockNumber: Default + From<u32>> Default for HostConfiguration<BlockNumber
  thread_availability_period: 1u32.into(),
  no_show_slots: 1u32.into(),
  validation_upgrade_frequency: Default::default(),
- validation_upgrade_delay: Default::default(),
+ validation_upgrade_delay: 2u32.into(),
  code_retention_period: Default::default(),
  max_code_size: Default::default(),
  max_pov_size: Default::default(),
@@ -288,9 +288,14 @@ pub enum InconsistentError<BlockNumber> {
  minimum_validation_upgrade_delay: BlockNumber,
  thread_availability_period: BlockNumber,
  },
+ /// `validation_upgrade_delay` is less than or equal 1.
+ ValidationUpgradeDelayIsTooLow { validation_upgrade_delay: BlockNumber },
 }
 
-impl<BlockNumber: Zero + PartialOrd + sp_std::fmt::Debug + Clone> HostConfiguration<BlockNumber> {
+impl<BlockNumber> HostConfiguration<BlockNumber>
+where
+ BlockNumber: Zero + PartialOrd + sp_std::fmt::Debug + Clone + From<u32>,
+{
  /// Checks that this instance is consistent with the requirements on each individual member.
  ///
  /// # Errors
@@ -341,6 +346,12 @@ impl<BlockNumber: Zero + PartialOrd + sp_std::fmt::Debug + Clone> HostConfigurat
  })
  }
 
+ if self.validation_upgrade_delay <= 1.into() {
+ return Err(ValidationUpgradeDelayIsTooLow {
+ validation_upgrade_delay: self.validation_upgrade_delay.clone(),
+ })
+ }
+
  Ok(())
  }
 
@@ -1499,6 +1510,11 @@ mod tests {
  Configuration::set_minimum_validation_upgrade_delay(Origin::root(), 9),
  Error::<Test>::InvalidNewValue
  );
+
+ assert_err!(
+ Configuration::set_validation_upgrade_delay(Origin::root(), 0),
+ Error::<Test>::InvalidNewValue
+ );
  });
  }
 

runtime/parachains/src/inclusion/tests.rs

@@ -1307,7 +1307,7 @@ fn candidate_checks() {
  {
  let cfg = Configuration::config();
  let expected_at = 10 + cfg.validation_upgrade_delay;
- assert_eq!(expected_at, 10);
+ assert_eq!(expected_at, 12);
  Paras::schedule_code_upgrade(chain_a, vec![1, 2, 3, 4].into(), expected_at, &cfg);
  }