test(e2e): relay across a Besu validator turnover

e2e/README.md

@@ -10,7 +10,7 @@ This repository-level surface hosts one black-box acceptance package. Its tests
 
 The root package covers ICS20 transfer, ICS27 GMP, IFT (burn/mint on top of GMP) relay behavior, timeout refunds, error acknowledgements, pending-packet status, Relayer and node recovery, attestor quorum loss and recovery, cross-route handling, and relaying through an attached RPC that `Environment` does not own. These are all acceptance criteria and run together by default.
 
-Besu light clients are covered through a two-chain Besu mesh, which requires the Besu provider and therefore skips in fast mode. `TestTransferBesuQBFT_AutoRelay` exercises client updates from sealed headers, membership proofs and acknowledgement; `TestTransferBesuQBFT_TimeoutRefund` exercises the non-membership proof of a timeout, letting the packet expire in real time; `TestTransferBesuIBFT2_AutoRelay` repeats the transfer on IBFT 2.0 chains. `TestDeployBesuQBFTIBFT2Connection` deploys a besu connection between a QBFT and an IBFT 2.0 chain with `ibc deploy client besu` alone, so each client detects a different consensus, and relays an IFT transfer over it; `TestDeployMixedBesuQBFTAttestationConnection` does the same for the production shape, a besu client on one end and an attestation client on the other, relaying a round trip so each client type proves both a receive and an acknowledgement. Client expiry is not exercised end-to-end: it would need the Besu clock moved past the trusting period.
+Besu light clients are covered through a two-chain Besu mesh, which requires the Besu provider and therefore skips in fast mode. `TestTransferBesuQBFT_AutoRelay` exercises client updates from sealed headers, membership proofs and acknowledgement; `TestTransferBesuQBFT_TimeoutRefund` exercises the non-membership proof of a timeout, letting the packet expire in real time; `TestTransferBesuIBFT2_AutoRelay` repeats the transfer on IBFT 2.0 chains. `TestDeployBesuQBFTIBFT2Connection` deploys a besu connection between a QBFT and an IBFT 2.0 chain with `ibc deploy client besu` alone, so each client detects a different consensus, and relays an IFT transfer over it; `TestDeployMixedBesuQBFTAttestationConnection` does the same for the production shape, a besu client on one end and an attestation client on the other, relaying a round trip so each client type proves both a receive and an acknowledgement. `TestTransferBesuQBFT_ValidatorTurnover` and `TestTransferBesuIBFT2_ValidatorTurnover` run the source chain on two nodes and, before any packet is relayed, vote the second node in as a validator and the first out, so the relayer must step the destination's client across both set changes to relay a transfer. Their clients are deployed at a trust level of one half through `NewBesuClient.TrustLevel`, since at the default two thirds the client cannot follow the removal. `ManagedBesu.Nodes` adds the follower nodes and `Chain.Validators` votes through them. Client expiry is not exercised end-to-end: it would need the Besu clock moved past the trusting period.
 
 ## Running the acceptance tests
 

e2e/internal/e2etest/matrix.go

@@ -167,7 +167,11 @@ func summarizeSpec(spec environment.Spec) MatrixSpec {
 		case environment.ManagedAnvil:
 			counts["Anvil"]++
 		case environment.ManagedBesu:
-			counts["Besu "+strings.ToUpper(string(chain.Consensus))]++
+			typ := "Besu " + strings.ToUpper(string(chain.Consensus))
+			if chain.Nodes > 1 {
+				typ += fmt.Sprintf(" (%d nodes)", chain.Nodes)
+			}
+			counts[typ]++
 		case environment.AttachedEVM:
 			counts["Attached EVM"]++
 		default:

e2e/internal/e2etest/matrix_test.go

@@ -56,7 +56,10 @@ func TestMatrixCollectorJoinsSelectionsAndSpec(t *testing.T) {
 
 	// new and existing Besu clients count alike, and never as attestors
 	besuSummary := summarizeSpec(environment.Spec{
-		Chains: []environment.ChainSpec{environment.ManagedBesu{Consensus: besu.IBFT2}},
+		Chains: []environment.ChainSpec{
+			environment.ManagedBesu{Consensus: besu.IBFT2},
+			environment.ManagedBesu{Consensus: besu.IBFT2, Nodes: 2},
+		},
 		Connections: []environment.ConnectionSpec{{
 			A: environment.NewBesuClient{},
 			B: environment.ExistingClient{Kind: clientkind.Besu},
@@ -65,7 +68,8 @@ func TestMatrixCollectorJoinsSelectionsAndSpec(t *testing.T) {
 	if besuSummary.BesuClients != 2 || besuSummary.Attestors != 0 {
 		t.Fatalf("besu summary = %#v", besuSummary)
 	}
-	if got := besuSummary.Chains; len(got) != 1 || got[0].Type != "Besu IBFT2" {
+	got := besuSummary.Chains
+	if len(got) != 2 || got[0].Type != "Besu IBFT2" || got[1].Type != "Besu IBFT2 (2 nodes)" {
 		t.Fatalf("besu ibft2 chain summary = %#v", got)
 	}
 }

e2e/internal/harness/chain/capabilities.go

@@ -28,3 +28,11 @@ type FaultInjector interface {
 type EOAFunder interface {
 	EnsureEOABalance(ctx context.Context, address common.Address, minimum *big.Int) error
 }
+
+// ValidatorVoter changes a BFT chain's validator set through header voting,
+// across nodes the managed Chain runs.
+type ValidatorVoter interface {
+	Nodes() []common.Address
+	Validators(ctx context.Context) ([]common.Address, error)
+	VoteValidator(ctx context.Context, validator common.Address, add bool) error
+}