Add ChainTime associated type (#410)

* add HeaderTimestamp associated type

* use Header Timestamp

* rename HeaderTimestamp to ChainTime

* add unit test

* deal with clippy

* Apply suggestions from code review

Commit review suggestions

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* code review

* cargo fmt

* get rid of additional test runtime

* unit test asserts against concrete import context

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

bridges/modules/ethereum/src/mock.rs

@@ -18,7 +18,7 @@ pub use crate::test_utils::{insert_header, validator_utils::*, validators_change
 pub use bp_eth_poa::signatures::secret_to_address;
 
 use crate::validators::{ValidatorsConfiguration, ValidatorsSource};
-use crate::{AuraConfiguration, GenesisConfig, PruningStrategy, Trait};
+use crate::{AuraConfiguration, ChainTime, GenesisConfig, PruningStrategy, Trait};
 use bp_eth_poa::{Address, AuraHeader, H256, U256};
 use frame_support::{impl_outer_origin, parameter_types, weights::Weight};
 use secp256k1::SecretKey;
@@ -83,6 +83,7 @@ impl Trait for TestRuntime {
 	type ValidatorsConfiguration = TestValidatorsConfiguration;
 	type FinalityVotesCachingInterval = TestFinalityVotesCachingInterval;
 	type PruningStrategy = KeepSomeHeadersBehindBest;
+	type ChainTime = ConstChainTime;
 	type OnHeadersSubmitted = ();
 }
 
@@ -168,3 +169,14 @@ impl PruningStrategy for KeepSomeHeadersBehindBest {
 		best_number.saturating_sub(self.0)
 	}
 }
+
+/// Constant chain time
+#[derive(Default)]
+pub struct ConstChainTime;
+
+impl ChainTime for ConstChainTime {
+	fn is_timestamp_ahead(&self, timestamp: u64) -> bool {
+		let now = i32::max_value() as u64 / 2;
+		timestamp > now
+	}
+}