From 23d928184de45aa943d3aff7710285406d178e0c Mon Sep 17 00:00:00 2001
From: Simon Noetzlin <simon.ntz@gmail.com>
Date: Wed, 9 Oct 2024 16:49:54 +0200
Subject: [PATCH 1/2] Introduce two following changes to the `commitBlock`
 method in testing: * increment the proposer priority of validators * update
 the proposer address in the current header

---
 CHANGELOG.md          |  4 ++++
 testing/chain.go      |  5 ++++-
 testing/chain_test.go | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index e2225e03952..e68c1a222da 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -36,6 +36,10 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ## [Unreleased]
 
+### Testing
+
+* [\#7430](https://github.com/cosmos/ibc-go/pull/7430) Update the block proposer in test chains for each block.
+
 ### Dependencies
 
 * [\#7247](https://github.com/cosmos/ibc-go/pull/7247) Bump CometBFT to v0.38.12.
diff --git a/testing/chain.go b/testing/chain.go
index e7b254db2ee..a898b64fd3d 100644
--- a/testing/chain.go
+++ b/testing/chain.go
@@ -323,6 +323,9 @@ func (chain *TestChain) commitBlock(res *abci.ResponseFinalizeBlock) {
 	chain.Vals = chain.NextVals
 	chain.NextVals = ApplyValSetChanges(chain, chain.Vals, res.ValidatorUpdates)
 
+	// increment the proposer priority of validators
+	chain.Vals.IncrementProposerPriority(1)
+
 	// increment the current header
 	chain.ProposedHeader = cmtproto.Header{
 		ChainID: chain.ChainID,
@@ -333,7 +336,7 @@ func (chain *TestChain) commitBlock(res *abci.ResponseFinalizeBlock) {
 		Time:               chain.ProposedHeader.Time,
 		ValidatorsHash:     chain.Vals.Hash(),
 		NextValidatorsHash: chain.NextVals.Hash(),
-		ProposerAddress:    chain.ProposedHeader.ProposerAddress,
+		ProposerAddress:    chain.Vals.Proposer.Address,
 	}
 }
 
diff --git a/testing/chain_test.go b/testing/chain_test.go
index 512e426eaca..5cab5dd5dd4 100644
--- a/testing/chain_test.go
+++ b/testing/chain_test.go
@@ -6,6 +6,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	sdkmath "cosmossdk.io/math"
+	sdk "github.com/cosmos/cosmos-sdk/types"
 
 	"github.com/cosmos/cosmos-sdk/x/staking/types"
 
@@ -41,3 +42,36 @@ func TestChangeValSet(t *testing.T) {
 	err = path.EndpointB.UpdateClient()
 	require.NoError(t, err)
 }
+
+func TestJailProposerValidator(t *testing.T) {
+	coord := ibctesting.NewCoordinator(t, 2)
+	chainA := coord.GetChain(ibctesting.GetChainID(1))
+	chainB := coord.GetChain(ibctesting.GetChainID(2))
+
+	path := ibctesting.NewPath(chainA, chainB)
+	coord.Setup(path)
+
+	// save valset length before jailing
+	valsetLen := len(chainA.Vals.Validators)
+
+	// jail the proposer validator in chain A
+	propAddr := sdk.ConsAddress(chainA.Vals.Proposer.Address)
+
+	err := chainA.GetSimApp().StakingKeeper.Jail(
+		chainA.GetContext(), propAddr)
+	require.NoError(t, err)
+
+	coord.CommitBlock(chainA)
+
+	// verify that update clients works even after validator update goes into effect
+	err = path.EndpointB.UpdateClient()
+	require.NoError(t, err)
+	err = path.EndpointB.UpdateClient()
+	require.NoError(t, err)
+
+	// check that the jailing has taken effect in chain A
+	require.Equal(t, valsetLen-1, len(chainA.Vals.Validators))
+
+	// check that the valset in chain A has a new proposer
+	require.False(t, propAddr.Equals(sdk.ConsAddress(chainA.Vals.Proposer.Address)))
+}

From 796396886d128c5b454ff8a8923cdc3fea4fdd46 Mon Sep 17 00:00:00 2001
From: Simon Noetzlin <simon.ntz@gmail.com>
Date: Mon, 14 Oct 2024 14:31:12 +0200
Subject: [PATCH 2/2] fix linter

---
 testing/chain_test.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/testing/chain_test.go b/testing/chain_test.go
index 5cab5dd5dd4..e72057765b3 100644
--- a/testing/chain_test.go
+++ b/testing/chain_test.go
@@ -6,8 +6,8 @@ import (
 	"github.com/stretchr/testify/require"
 
 	sdkmath "cosmossdk.io/math"
-	sdk "github.com/cosmos/cosmos-sdk/types"
 
+	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/staking/types"
 
 	ibctesting "github.com/cosmos/ibc-go/v9/testing"