From 527a11a2bbe59e172649d5c22b87878d86859806 Mon Sep 17 00:00:00 2001
From: Cian Hatton <cian@interchain.io>
Date: Wed, 6 Jul 2022 11:04:28 +0100
Subject: [PATCH 1/9] Script to dynamically generate list of e2e tests (E2E #1)
 (#1644)

---
 .github/scripts/build_test_matrix.go      | 130 +++++++++++++++++
 .github/scripts/build_test_matrix_test.go | 162 ++++++++++++++++++++++
 .github/workflows/test.yml                |   2 +-
 Makefile                                  |   2 +-
 4 files changed, 294 insertions(+), 2 deletions(-)
 create mode 100644 .github/scripts/build_test_matrix.go
 create mode 100644 .github/scripts/build_test_matrix_test.go

diff --git a/.github/scripts/build_test_matrix.go b/.github/scripts/build_test_matrix.go
new file mode 100644
index 00000000000..c86324b31f8
--- /dev/null
+++ b/.github/scripts/build_test_matrix.go
@@ -0,0 +1,130 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+const (
+	testNamePrefix     = "Test"
+	testFileNameSuffix = "_test.go"
+	e2eTestDirectory   = "e2e"
+)
+
+// GithubActionTestMatrix represents
+type GithubActionTestMatrix struct {
+	Include []TestSuitePair `json:"include"`
+}
+
+type TestSuitePair struct {
+	Test  string `json:"test"`
+	Suite string `json:"suite"`
+}
+
+func main() {
+	githubActionMatrix, err := getGithubActionMatrixForTests(e2eTestDirectory)
+	if err != nil {
+		fmt.Printf("error generating github action json: %s", err)
+		os.Exit(1)
+	}
+
+	ghBytes, err := json.Marshal(githubActionMatrix)
+	if err != nil {
+		fmt.Printf("error marshalling github action json: %s", err)
+		os.Exit(1)
+	}
+	fmt.Println(string(ghBytes))
+}
+
+// getGithubActionMatrixForTests returns a json string representing the contents that should go in the matrix
+// field in a github action workflow. This string can be used with `fromJSON(str)` to dynamically build
+// the workflow matrix to include all E2E tests under the e2eRootDirectory directory.
+func getGithubActionMatrixForTests(e2eRootDirectory string) (GithubActionTestMatrix, error) {
+	testSuiteMapping := map[string][]string{}
+	fset := token.NewFileSet()
+	err := filepath.Walk(e2eRootDirectory, func(path string, info fs.FileInfo, err error) error {
+		// only look at test files
+		if !strings.HasSuffix(path, testFileNameSuffix) {
+			return nil
+		}
+
+		f, err := parser.ParseFile(fset, path, nil, 0)
+		if err != nil {
+			return fmt.Errorf("failed parsing file: %s", err)
+		}
+
+		suiteNameForFile, testCases, err := extractSuiteAndTestNames(f)
+		if err != nil {
+			return fmt.Errorf("failed extracting test suite name and test cases: %s", err)
+		}
+
+		testSuiteMapping[suiteNameForFile] = testCases
+
+		return nil
+	})
+
+	if err != nil {
+		return GithubActionTestMatrix{}, err
+	}
+
+	gh := GithubActionTestMatrix{
+		Include: []TestSuitePair{},
+	}
+
+	for testSuiteName, testCases := range testSuiteMapping {
+		for _, testCaseName := range testCases {
+			gh.Include = append(gh.Include, TestSuitePair{
+				Test:  testCaseName,
+				Suite: testSuiteName,
+			})
+		}
+	}
+
+	return gh, nil
+}
+
+// extractSuiteAndTestNames extracts the name of the test suite function as well
+// as all tests associated with it in the same file.
+func extractSuiteAndTestNames(file *ast.File) (string, []string, error) {
+	var suiteNameForFile string
+	var testCases []string
+
+	for _, d := range file.Decls {
+		if f, ok := d.(*ast.FuncDecl); ok {
+			functionName := f.Name.Name
+			if isTestSuiteMethod(f) {
+				if suiteNameForFile != "" {
+					return "", nil, fmt.Errorf("found a second test function: %s when %s was already found", f.Name.Name, suiteNameForFile)
+				}
+				suiteNameForFile = functionName
+				continue
+			}
+			if isTestFunction(f) {
+				testCases = append(testCases, functionName)
+			}
+		}
+	}
+	if suiteNameForFile == "" {
+		return "", nil, fmt.Errorf("file %s had no test suite test case", file.Name.Name)
+	}
+	return suiteNameForFile, testCases, nil
+}
+
+// isTestSuiteMethod returns true if the function is a test suite function.
+// e.g. func TestFeeMiddlewareTestSuite(t *testing.T) { ... }
+func isTestSuiteMethod(f *ast.FuncDecl) bool {
+	return strings.HasPrefix(f.Name.Name, testNamePrefix) && len(f.Type.Params.List) == 1
+}
+
+// isTestFunction returns true if the function name starts with "Test" and has no parameters.
+// as test suite functions do not accept a *testing.T.
+func isTestFunction(f *ast.FuncDecl) bool {
+	return strings.HasPrefix(f.Name.Name, testNamePrefix) && len(f.Type.Params.List) == 0
+}
diff --git a/.github/scripts/build_test_matrix_test.go b/.github/scripts/build_test_matrix_test.go
new file mode 100644
index 00000000000..47de4d981c2
--- /dev/null
+++ b/.github/scripts/build_test_matrix_test.go
@@ -0,0 +1,162 @@
+package main
+
+import (
+	"os"
+	"path"
+	"sort"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+const (
+	nonTestFile       = "not_test_file.go"
+	goTestFileNameOne = "first_go_file_test.go"
+	goTestFileNameTwo = "second_go_file_test.go"
+)
+
+func TestGetGithubActionMatrixForTests(t *testing.T) {
+	t.Run("empty dir does not fail", func(t *testing.T) {
+		testingDir := t.TempDir()
+		_, err := getGithubActionMatrixForTests(testingDir)
+		assert.NoError(t, err)
+	})
+
+	t.Run("only test functions are picked up", func(t *testing.T) {
+		testingDir := t.TempDir()
+		createFileWithTestSuiteAndTests(t, "FeeMiddlewareTestSuite", "TestA", "TestB", testingDir, goTestFileNameOne)
+
+		gh, err := getGithubActionMatrixForTests(testingDir)
+		assert.NoError(t, err)
+
+		expected := GithubActionTestMatrix{
+			Include: []TestSuitePair{
+				{
+					Suite: "TestFeeMiddlewareTestSuite",
+					Test:  "TestA",
+				},
+				{
+					Suite: "TestFeeMiddlewareTestSuite",
+					Test:  "TestB",
+				},
+			},
+		}
+		assertGithubActionTestMatricesEqual(t, expected, gh)
+	})
+
+	t.Run("all files are picked up", func(t *testing.T) {
+		testingDir := t.TempDir()
+		createFileWithTestSuiteAndTests(t, "FeeMiddlewareTestSuite", "TestA", "TestB", testingDir, goTestFileNameOne)
+		createFileWithTestSuiteAndTests(t, "TransferTestSuite", "TestC", "TestD", testingDir, goTestFileNameTwo)
+
+		gh, err := getGithubActionMatrixForTests(testingDir)
+		assert.NoError(t, err)
+
+		expected := GithubActionTestMatrix{
+			Include: []TestSuitePair{
+				{
+					Suite: "TestTransferTestSuite",
+					Test:  "TestC",
+				},
+				{
+					Suite: "TestFeeMiddlewareTestSuite",
+					Test:  "TestA",
+				},
+				{
+					Suite: "TestFeeMiddlewareTestSuite",
+					Test:  "TestB",
+				},
+				{
+					Suite: "TestTransferTestSuite",
+					Test:  "TestD",
+				},
+			},
+		}
+
+		assertGithubActionTestMatricesEqual(t, expected, gh)
+	})
+
+	t.Run("non test files are not picked up", func(t *testing.T) {
+		testingDir := t.TempDir()
+		createFileWithTestSuiteAndTests(t, "FeeMiddlewareTestSuite", "TestA", "TestB", testingDir, nonTestFile)
+
+		gh, err := getGithubActionMatrixForTests(testingDir)
+		assert.NoError(t, err)
+		assert.Empty(t, gh.Include)
+	})
+
+	t.Run("fails when there are multiple suite runs", func(t *testing.T) {
+		testingDir := t.TempDir()
+		createFileWithTestSuiteAndTests(t, "FeeMiddlewareTestSuite", "TestA", "TestB", testingDir, nonTestFile)
+
+		fileWithTwoSuites := `package foo
+func SuiteOne(t *testing.T) {
+	suite.Run(t, new(FeeMiddlewareTestSuite))
+}
+
+func SuiteTwo(t *testing.T) {
+	suite.Run(t, new(FeeMiddlewareTestSuite))
+}
+
+type FeeMiddlewareTestSuite struct {}
+`
+
+		err := os.WriteFile(path.Join(testingDir, goTestFileNameOne), []byte(fileWithTwoSuites), os.FileMode(777))
+		assert.NoError(t, err)
+
+		_, err = getGithubActionMatrixForTests(testingDir)
+		assert.Error(t, err)
+	})
+}
+
+func assertGithubActionTestMatricesEqual(t *testing.T, expected, actual GithubActionTestMatrix) {
+	// sort by both suite and test as the order of the end result does not matter as
+	// all tests will be run.
+	sort.SliceStable(expected.Include, func(i, j int) bool {
+		memberI := expected.Include[i]
+		memberJ := expected.Include[j]
+		if memberI.Suite == memberJ.Suite {
+			return memberI.Test < memberJ.Test
+		}
+		return memberI.Suite < memberJ.Suite
+	})
+
+	sort.SliceStable(actual.Include, func(i, j int) bool {
+		memberI := actual.Include[i]
+		memberJ := actual.Include[j]
+		if memberI.Suite == memberJ.Suite {
+			return memberI.Test < memberJ.Test
+		}
+		return memberI.Suite < memberJ.Suite
+	})
+	assert.Equal(t, expected.Include, actual.Include)
+}
+
+func goTestFileContents(suiteName, fnName1, fnName2 string) string {
+
+	replacedSuiteName := strings.ReplaceAll(`package foo
+
+func TestSuiteName(t *testing.T) {
+	suite.Run(t, new(SuiteName))
+}
+
+type SuiteName struct {}
+
+func (s *SuiteName) fnName1() {}
+func (s *SuiteName) fnName2() {}
+
+func (s *SuiteName) suiteHelper() {}
+
+func helper() {}
+`, "SuiteName", suiteName)
+
+	replacedFn1Name := strings.ReplaceAll(replacedSuiteName, "fnName1", fnName1)
+	return strings.ReplaceAll(replacedFn1Name, "fnName2", fnName2)
+}
+
+func createFileWithTestSuiteAndTests(t *testing.T, suiteName, fn1Name, fn2Name, dir, filename string) {
+	goFileContents := goTestFileContents(suiteName, fn1Name, fn2Name)
+	err := os.WriteFile(path.Join(dir, filename), []byte(goFileContents), os.FileMode(777))
+	assert.NoError(t, err)
+}
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index c915db779cd..ff8ed4d65d9 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -63,7 +63,7 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - name: Create a file with all the pkgs
-        run: go list ./... > pkgs.txt
+        run: go list ./... ./.github/scripts > pkgs.txt
       - name: Split pkgs into 4 files
         run: split -d -n l/4 pkgs.txt pkgs.txt.part.
       # cache multiple
diff --git a/Makefile b/Makefile
index 0ea7f0c10c5..9beb4ab61bc 100644
--- a/Makefile
+++ b/Makefile
@@ -216,7 +216,7 @@ view-docs:
 test: test-unit
 test-all: test-unit test-ledger-mock test-race test-cover
 
-TEST_PACKAGES=./...
+TEST_PACKAGES=./... ./.github/scripts
 TEST_TARGETS := test-unit test-unit-amino test-unit-proto test-ledger-mock test-race test-ledger test-race
 
 # Test runs-specific rules. To add a new test target, just add

From 40771a6e582d4f806880dc8942af81070a039f6d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Colin=20Axn=C3=A9r?=
 <25233464+colin-axner@users.noreply.github.com>
Date: Thu, 7 Jul 2022 12:31:41 +0200
Subject: [PATCH 2/9] apply remaining changes for crossing hello removal

Deprecate previous channel id with proto tag
Remove unnecessary test cases from 04-channel
Remove crossing hello check in transfer application and the associated test case
---
 CHANGELOG.md                                  |  2 +-
 .../adr-006-02-client-refactor.md             | 40 +++++++++++++++++++
 modules/apps/29-fee/ibc_middleware_test.go    | 22 ++--------
 modules/apps/transfer/ibc_module.go           | 11 +----
 modules/apps/transfer/ibc_module_test.go      |  4 +-
 .../core/04-channel/keeper/handshake_test.go  | 14 -------
 proto/ibc/core/channel/v1/tx.proto            |  6 +--
 testing/coordinator.go                        | 21 ----------
 8 files changed, 50 insertions(+), 70 deletions(-)
 create mode 100644 docs/architecture/adr-006-02-client-refactor.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2f29f71a503..0de36fb4c9a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -62,7 +62,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (modules/core/04-channel) [\#1232](https://github.com/cosmos/ibc-go/pull/1232) Updating params on `NewPacketId` and moving to bottom of file.
 * (app/29-fee) [\#1305](https://github.com/cosmos/ibc-go/pull/1305) Change version string for fee module to `ics29-1`
 * (app/29-fee) [\#1341](https://github.com/cosmos/ibc-go/pull/1341) Check if the fee module is locked and if the fee module is enabled before refunding all fees
-* (modules/core/04-channel) [\#1317](https://github.com/cosmos/ibc-go/pull/1317)  Remove crossing hellos from ChanOpenTry
+* (modules/core/04-channel) [\#1317](https://github.com/cosmos/ibc-go/pull/1317) Remove corssing hellos from channel handshakes. The `PreviousChannelId` in `MsgChannelOpenTry` has been deprecated.  
 * (transfer) [\#1414](https://github.com/cosmos/ibc-go/pull/1414) Emitting Sender address from `fungible_token_packet` events in `OnRecvPacket` and `OnAcknowledgementPacket`.
 * (testing/simapp) [\#1397](https://github.com/cosmos/ibc-go/pull/1397) Adding mock module to maccperms and adding check to ensure mock module is not a blocked account address. 
 * (core/02-client) [\#1570](https://github.com/cosmos/ibc-go/pull/1570) Emitting an event when handling an upgrade client proposal. 
diff --git a/docs/architecture/adr-006-02-client-refactor.md b/docs/architecture/adr-006-02-client-refactor.md
new file mode 100644
index 00000000000..55ff76544cb
--- /dev/null
+++ b/docs/architecture/adr-006-02-client-refactor.md
@@ -0,0 +1,40 @@
+# ADR 006: 02-client refactor
+
+## Changelog
+* 18 May 2022: Initial Draft
+
+## Status
+
+Accepted
+
+## Context
+
+> This section contains all the context one needs to understand the current state, and why there is a problem. It should be as succinct as possible and introduce the high level idea behind the solution. 
+
+## Decision
+
+> This section explains all of the details of the proposed solution, including implementation details.
+It should also describe affects / corollary items that may need to be changed as a part of this.
+If the proposed change will be large, please also indicate a way to do the change to maximize ease of review.
+(e.g. the optimal split of things to do between separate PR's)
+
+## Consequences
+
+> This section describes the consequences, after applying the decision. All consequences should be summarized here, not just the "positive" ones.
+
+### Positive
+
+### Negative
+
+### Neutral
+
+## References
+
+The primary discussion which motivated these changes was documented in issue [#284](https://github.com/cosmos/ibc-go/issues/284).
+
+Issues:
+* {reference link}
+
+PRs:
+* {ref}
+
diff --git a/modules/apps/29-fee/ibc_middleware_test.go b/modules/apps/29-fee/ibc_middleware_test.go
index 6f0de4b1971..ea7cdcae8b6 100644
--- a/modules/apps/29-fee/ibc_middleware_test.go
+++ b/modules/apps/29-fee/ibc_middleware_test.go
@@ -141,38 +141,27 @@ func (suite *FeeTestSuite) TestOnChanOpenTry() {
 	testCases := []struct {
 		name      string
 		cpVersion string
-		crossing  bool
 		expPass   bool
 	}{
 		{
 			"success - valid fee middleware version",
 			string(types.ModuleCdc.MustMarshalJSON(&types.Metadata{FeeVersion: types.Version, AppVersion: ibcmock.Version})),
-			false,
 			true,
 		},
 		{
 			"success - valid mock version",
 			ibcmock.Version,
-			false,
-			true,
-		},
-		{
-			"success - crossing hellos: valid fee middleware",
-			string(types.ModuleCdc.MustMarshalJSON(&types.Metadata{FeeVersion: types.Version, AppVersion: ibcmock.Version})),
-			true,
 			true,
 		},
 		{
 			"invalid fee middleware version",
 			string(types.ModuleCdc.MustMarshalJSON(&types.Metadata{FeeVersion: "invalid-ics29-1", AppVersion: ibcmock.Version})),
 			false,
-			false,
 		},
 		{
 			"invalid mock version",
 			string(types.ModuleCdc.MustMarshalJSON(&types.Metadata{FeeVersion: types.Version, AppVersion: "invalid-mock-version"})),
 			false,
-			false,
 		},
 	}
 
@@ -201,14 +190,9 @@ func (suite *FeeTestSuite) TestOnChanOpenTry() {
 				ok      bool
 				err     error
 			)
-			if tc.crossing {
-				suite.path.EndpointA.ChanOpenInit()
-				chanCap, ok = suite.chainA.GetSimApp().ScopedFeeMockKeeper.GetCapability(suite.chainA.GetContext(), host.ChannelCapabilityPath(suite.path.EndpointA.ChannelConfig.PortID, suite.path.EndpointA.ChannelID))
-				suite.Require().True(ok)
-			} else {
-				chanCap, err = suite.chainA.App.GetScopedIBCKeeper().NewCapability(suite.chainA.GetContext(), host.ChannelCapabilityPath(suite.path.EndpointA.ChannelConfig.PortID, suite.path.EndpointA.ChannelID))
-				suite.Require().NoError(err)
-			}
+
+			chanCap, err = suite.chainA.App.GetScopedIBCKeeper().NewCapability(suite.chainA.GetContext(), host.ChannelCapabilityPath(suite.path.EndpointA.ChannelConfig.PortID, suite.path.EndpointA.ChannelID))
+			suite.Require().NoError(err)
 
 			suite.path.EndpointA.ChannelID = ibctesting.FirstChannelID
 
diff --git a/modules/apps/transfer/ibc_module.go b/modules/apps/transfer/ibc_module.go
index 7b87b33408c..d2b78001e99 100644
--- a/modules/apps/transfer/ibc_module.go
+++ b/modules/apps/transfer/ibc_module.go
@@ -111,15 +111,8 @@ func (im IBCModule) OnChanOpenTry(
 		return "", sdkerrors.Wrapf(types.ErrInvalidVersion, "invalid counterparty version: got: %s, expected %s", counterpartyVersion, types.Version)
 	}
 
-	// Module may have already claimed capability in OnChanOpenInit in the case of crossing hellos
-	// (ie chainA and chainB both call ChanOpenInit before one of them calls ChanOpenTry)
-	// If module can already authenticate the capability then module already owns it so we don't need to claim
-	// Otherwise, module does not have channel capability and we must claim it from IBC
-	if !im.keeper.AuthenticateCapability(ctx, chanCap, host.ChannelCapabilityPath(portID, channelID)) {
-		// Only claim channel capability passed back by IBC module if we do not already own it
-		if err := im.keeper.ClaimCapability(ctx, chanCap, host.ChannelCapabilityPath(portID, channelID)); err != nil {
-			return "", err
-		}
+	if err := im.keeper.ClaimCapability(ctx, chanCap, host.ChannelCapabilityPath(portID, channelID)); err != nil {
+		return "", err
 	}
 
 	return types.Version, nil
diff --git a/modules/apps/transfer/ibc_module_test.go b/modules/apps/transfer/ibc_module_test.go
index 3b8e0175517..3ff7b25679e 100644
--- a/modules/apps/transfer/ibc_module_test.go
+++ b/modules/apps/transfer/ibc_module_test.go
@@ -124,10 +124,10 @@ func (suite *TransferTestSuite) TestOnChanOpenTry() {
 			}, false,
 		},
 		{
-			"capability already claimed in INIT should pass", func() {
+			"capability already claimed", func() {
 				err := suite.chainA.GetSimApp().ScopedTransferKeeper.ClaimCapability(suite.chainA.GetContext(), chanCap, host.ChannelCapabilityPath(path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID))
 				suite.Require().NoError(err)
-			}, true,
+			}, false,
 		},
 		{
 			"invalid order - ORDERED", func() {
diff --git a/modules/core/04-channel/keeper/handshake_test.go b/modules/core/04-channel/keeper/handshake_test.go
index 9e62c030aba..e8750f85b05 100644
--- a/modules/core/04-channel/keeper/handshake_test.go
+++ b/modules/core/04-channel/keeper/handshake_test.go
@@ -157,20 +157,6 @@ func (suite *KeeperTestSuite) TestChanOpenTry() {
 			suite.chainB.CreatePortCapability(suite.chainB.GetSimApp().ScopedIBCMockKeeper, ibctesting.MockPort)
 			portCap = suite.chainB.GetPortCapability(ibctesting.MockPort)
 		}, true},
-		{"success with crossing hello", func() {
-			suite.coordinator.SetupConnections(path)
-			path.SetChannelOrdered()
-			err := suite.coordinator.ChanOpenInitOnBothChains(path)
-			suite.Require().NoError(err)
-
-			portCap = suite.chainB.GetPortCapability(ibctesting.MockPort)
-		}, true},
-		{"previous channel with invalid state", func() {
-			suite.coordinator.SetupConnections(path)
-
-			// make previous channel have wrong ordering
-			path.EndpointA.ChanOpenInit()
-		}, false},
 		{"connection doesn't exist", func() {
 			path.EndpointA.ConnectionID = ibctesting.FirstConnectionID
 			path.EndpointB.ConnectionID = ibctesting.FirstConnectionID
diff --git a/proto/ibc/core/channel/v1/tx.proto b/proto/ibc/core/channel/v1/tx.proto
index 210b7a71732..19101aef797 100644
--- a/proto/ibc/core/channel/v1/tx.proto
+++ b/proto/ibc/core/channel/v1/tx.proto
@@ -79,10 +79,8 @@ message MsgChannelOpenTry {
   option (gogoproto.goproto_getters) = false;
 
   string port_id = 1 [(gogoproto.moretags) = "yaml:\"port_id\""];
-  // in the case of crossing hello's, when both chains call OpenInit, we need
-  // the channel identifier of the previous channel in state INIT
-  // Deprecated: this field has been deprecated and will be ignored by core IBC because now we don't need to protect against crossing hellos anymore.
-  string previous_channel_id = 2 [(gogoproto.moretags) = "yaml:\"previous_channel_id\""];
+  // Deprecated: this field is unused. Crossing hello's are no longer supported in core IBC. 
+  string previous_channel_id = 2 [deprecated = true, (gogoproto.moretags) = "yaml:\"previous_channel_id\""];
   // NOTE: the version field within the channel has been deprecated. Its value will be ignored by core IBC.
   Channel                   channel              = 3 [(gogoproto.nullable) = false];
   string                    counterparty_version = 4 [(gogoproto.moretags) = "yaml:\"counterparty_version\""];
diff --git a/testing/coordinator.go b/testing/coordinator.go
index dde3eb56b1a..6aaf2ab748f 100644
--- a/testing/coordinator.go
+++ b/testing/coordinator.go
@@ -212,24 +212,3 @@ func (coord *Coordinator) ConnOpenInitOnBothChains(path *Path) error {
 
 	return path.EndpointB.UpdateClient()
 }
-
-// ChanOpenInitOnBothChains initializes a channel on the source chain and counterparty chain
-// with the state INIT using the OpenInit handshake call.
-func (coord *Coordinator) ChanOpenInitOnBothChains(path *Path) error {
-	// NOTE: only creation of a capability for a transfer or mock port is supported
-	// Other applications must bind to the port in InitGenesis or modify this code.
-
-	if err := path.EndpointA.ChanOpenInit(); err != nil {
-		return err
-	}
-
-	if err := path.EndpointB.ChanOpenInit(); err != nil {
-		return err
-	}
-
-	if err := path.EndpointA.UpdateClient(); err != nil {
-		return err
-	}
-
-	return path.EndpointB.UpdateClient()
-}

From c2eecabe525b50dd2fb20065bcb2ec49f041b87e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Colin=20Axn=C3=A9r?=
 <25233464+colin-axner@users.noreply.github.com>
Date: Thu, 7 Jul 2022 12:35:22 +0200
Subject: [PATCH 3/9] remove previous channel check in WriteChannelOpenTry

---
 modules/core/04-channel/keeper/handshake.go | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/modules/core/04-channel/keeper/handshake.go b/modules/core/04-channel/keeper/handshake.go
index 602ebc0a8f3..579ae9a25f1 100644
--- a/modules/core/04-channel/keeper/handshake.go
+++ b/modules/core/04-channel/keeper/handshake.go
@@ -188,18 +188,15 @@ func (k Keeper) WriteOpenTryChannel(
 	counterparty types.Counterparty,
 	version string,
 ) {
-	previousChannel, previousChannelFound := k.GetChannel(ctx, portID, channelID)
-	if !previousChannelFound {
-		k.SetNextSequenceSend(ctx, portID, channelID, 1)
-		k.SetNextSequenceRecv(ctx, portID, channelID, 1)
-		k.SetNextSequenceAck(ctx, portID, channelID, 1)
-	}
+	k.SetNextSequenceSend(ctx, portID, channelID, 1)
+	k.SetNextSequenceRecv(ctx, portID, channelID, 1)
+	k.SetNextSequenceAck(ctx, portID, channelID, 1)
 
 	channel := types.NewChannel(types.TRYOPEN, order, counterparty, connectionHops, version)
 
 	k.SetChannel(ctx, portID, channelID, channel)
 
-	k.Logger(ctx).Info("channel state updated", "port-id", portID, "channel-id", channelID, "previous-state", previousChannel.State.String(), "new-state", "TRYOPEN")
+	k.Logger(ctx).Info("channel state updated", "port-id", portID, "channel-id", channelID, "previous-state", "NONE", "new-state", "TRYOPEN")
 
 	defer func() {
 		telemetry.IncrCounter(1, "ibc", "channel", "open-try")

From 4f7e88a94802ff6cda6ed73e812dbc2f5f9b94ba Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Colin=20Axn=C3=A9r?=
 <25233464+colin-axner@users.noreply.github.com>
Date: Thu, 7 Jul 2022 12:37:57 +0200
Subject: [PATCH 4/9] regenerate proto files

---
 docs/ibc/proto-docs.md                 |   2 +-
 modules/core/04-channel/types/tx.pb.go | 169 ++++++++++++-------------
 proto/ibc/core/channel/v1/tx.proto     |   2 +-
 3 files changed, 86 insertions(+), 87 deletions(-)

diff --git a/docs/ibc/proto-docs.md b/docs/ibc/proto-docs.md
index 30c6d350bd1..ced55cfbc75 100644
--- a/docs/ibc/proto-docs.md
+++ b/docs/ibc/proto-docs.md
@@ -2949,7 +2949,7 @@ value will be ignored by core IBC.
 | Field | Type | Label | Description |
 | ----- | ---- | ----- | ----------- |
 | `port_id` | [string](#string) |  |  |
-| `previous_channel_id` | [string](#string) |  | in the case of crossing hello's, when both chains call OpenInit, we need the channel identifier of the previous channel in state INIT |
+| `previous_channel_id` | [string](#string) |  | **Deprecated.** Deprecated: this field is unused. Crossing hello's are no longer supported in core IBC. |
 | `channel` | [Channel](#ibc.core.channel.v1.Channel) |  | NOTE: the version field within the channel has been deprecated. Its value will be ignored by core IBC. |
 | `counterparty_version` | [string](#string) |  |  |
 | `proof_init` | [bytes](#bytes) |  |  |
diff --git a/modules/core/04-channel/types/tx.pb.go b/modules/core/04-channel/types/tx.pb.go
index 4c8d176bd15..6ad733decee 100644
--- a/modules/core/04-channel/types/tx.pb.go
+++ b/modules/core/04-channel/types/tx.pb.go
@@ -160,9 +160,8 @@ func (m *MsgChannelOpenInitResponse) GetVersion() string {
 // value will be ignored by core IBC.
 type MsgChannelOpenTry struct {
 	PortId string `protobuf:"bytes,1,opt,name=port_id,json=portId,proto3" json:"port_id,omitempty" yaml:"port_id"`
-	// in the case of crossing hello's, when both chains call OpenInit, we need
-	// the channel identifier of the previous channel in state INIT
-	PreviousChannelId string `protobuf:"bytes,2,opt,name=previous_channel_id,json=previousChannelId,proto3" json:"previous_channel_id,omitempty" yaml:"previous_channel_id"`
+	// Deprecated: this field is unused. Crossing hello's are no longer supported in core IBC.
+	PreviousChannelId string `protobuf:"bytes,2,opt,name=previous_channel_id,json=previousChannelId,proto3" json:"previous_channel_id,omitempty" yaml:"previous_channel_id"` // Deprecated: Do not use.
 	// NOTE: the version field within the channel has been deprecated. Its value will be ignored by core IBC.
 	Channel             Channel      `protobuf:"bytes,3,opt,name=channel,proto3" json:"channel"`
 	CounterpartyVersion string       `protobuf:"bytes,4,opt,name=counterparty_version,json=counterpartyVersion,proto3" json:"counterparty_version,omitempty" yaml:"counterparty_version"`
@@ -918,88 +917,88 @@ func init() {
 func init() { proto.RegisterFile("ibc/core/channel/v1/tx.proto", fileDescriptor_bc4637e0ac3fc7b7) }
 
 var fileDescriptor_bc4637e0ac3fc7b7 = []byte{
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+	// 1295 bytes of a gzipped FileDescriptorProto
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+	0xf1, 0xe3, 0xba, 0xa8, 0x9d, 0x74, 0xaa, 0x69, 0x41, 0x6e, 0x65, 0x04, 0x59, 0x6d, 0xc9, 0x6a,
+	0x46, 0xac, 0x0a, 0x1b, 0x75, 0x39, 0xd3, 0xdd, 0xce, 0xb4, 0xe4, 0x5a, 0xa7, 0x89, 0x54, 0xe3,
+	0xd7, 0xe3, 0x83, 0xed, 0x0d, 0xf3, 0xef, 0xa3, 0xd6, 0x6b, 0x23, 0xb5, 0x1a, 0xc2, 0x7f, 0x1e,
+	0x1f, 0xfe, 0x1b, 0x00, 0x00, 0xff, 0xff, 0x58, 0xd3, 0x8a, 0x27, 0x08, 0x15, 0x00, 0x00,
 }
 
 // Reference imports to suppress errors if they are not otherwise used.
diff --git a/proto/ibc/core/channel/v1/tx.proto b/proto/ibc/core/channel/v1/tx.proto
index 19101aef797..75248aeb5b1 100644
--- a/proto/ibc/core/channel/v1/tx.proto
+++ b/proto/ibc/core/channel/v1/tx.proto
@@ -79,7 +79,7 @@ message MsgChannelOpenTry {
   option (gogoproto.goproto_getters) = false;
 
   string port_id = 1 [(gogoproto.moretags) = "yaml:\"port_id\""];
-  // Deprecated: this field is unused. Crossing hello's are no longer supported in core IBC. 
+  // Deprecated: this field is unused. Crossing hello's are no longer supported in core IBC.
   string previous_channel_id = 2 [deprecated = true, (gogoproto.moretags) = "yaml:\"previous_channel_id\""];
   // NOTE: the version field within the channel has been deprecated. Its value will be ignored by core IBC.
   Channel                   channel              = 3 [(gogoproto.nullable) = false];

From 9856d241be7102c87cd100b0e22d4da20961a08b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Colin=20Axn=C3=A9r?=
 <25233464+colin-axner@users.noreply.github.com>
Date: Thu, 7 Jul 2022 12:41:57 +0200
Subject: [PATCH 5/9] update documentation

---
 docs/ibc/apps.md                    | 12 +++---------
 modules/apps/transfer/ibc_module.go |  1 +
 2 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/docs/ibc/apps.md b/docs/ibc/apps.md
index 267a2e5ca55..11fa1e84b7e 100644
--- a/docs/ibc/apps.md
+++ b/docs/ibc/apps.md
@@ -73,15 +73,9 @@ OnChanOpenTry(
     counterparty channeltypes.Counterparty,
     counterpartyVersion string,
 ) (string, error) {
-    // Module may have already claimed capability in OnChanOpenInit in the case of crossing hellos
-    // (ie chainA and chainB both call ChanOpenInit before one of them calls ChanOpenTry)
-    // If the module can already authenticate the capability then the module already owns it so we don't need to claim
-    // Otherwise, module does not have channel capability and we must claim it from IBC
-    if !k.AuthenticateCapability(ctx, chanCap, host.ChannelCapabilityPath(portID, channelID)) {
-        // Only claim channel capability passed back by IBC module if we do not already own it
-        if err := k.scopedKeeper.ClaimCapability(ctx, chanCap, host.ChannelCapabilityPath(portID, channelID)); err != nil {
-            return err
-        }
+    // OpenTry must claim the channelCapability that IBC passes into the callback
+    if err := k.scopedKeeper.ClaimCapability(ctx, chanCap, host.ChannelCapabilityPath(portID, channelID)); err != nil {
+        return err
     }
     
     // ... do custom initialization logic
diff --git a/modules/apps/transfer/ibc_module.go b/modules/apps/transfer/ibc_module.go
index d2b78001e99..6472c2998b0 100644
--- a/modules/apps/transfer/ibc_module.go
+++ b/modules/apps/transfer/ibc_module.go
@@ -111,6 +111,7 @@ func (im IBCModule) OnChanOpenTry(
 		return "", sdkerrors.Wrapf(types.ErrInvalidVersion, "invalid counterparty version: got: %s, expected %s", counterpartyVersion, types.Version)
 	}
 
+	// OpenTry must claim the channelCapability that IBC passes into the callback
 	if err := im.keeper.ClaimCapability(ctx, chanCap, host.ChannelCapabilityPath(portID, channelID)); err != nil {
 		return "", err
 	}

From a75219d3b4d92552c0a915a99452b594a718e66e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Colin=20Axn=C3=A9r?=
 <25233464+colin-axner@users.noreply.github.com>
Date: Thu, 7 Jul 2022 12:46:47 +0200
Subject: [PATCH 6/9] add migration documentation

---
 docs/migrations/v3-to-v4.md | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/docs/migrations/v3-to-v4.md b/docs/migrations/v3-to-v4.md
index 903c027ce4b..4fffedc9399 100644
--- a/docs/migrations/v3-to-v4.md
+++ b/docs/migrations/v3-to-v4.md
@@ -18,6 +18,10 @@ No genesis or in-place migrations required when upgrading from v1 or v2 of ibc-g
 
 ## Chains
 
+- No relevant changes were made in this release.
+
+## IBC Apps
+
 ### ICS04 - Channel 
 
 The `WriteAcknowledgement` API now takes the `exported.Acknowledgement` type instead of passing in the acknowledgement byte array directly. 
@@ -30,6 +34,10 @@ The `NewErrorAcknowledgement` method signature has changed.
 It now accepts an `error` rather than a `string`. This was done in order to prevent accidental state changes.
 All error acknowledgements now contain a deterministic ABCI code and error message. It is the responsibility of the application developer to emit error details in events.
 
+Crossing hellos have been removed from 04-channel handshake negotiation. 
+IBC Applications no longer need to account from already claimed capabilities in the `OnChanOpenTry` callback. The capability provided by core IBC must be able to be claimed with error. 
+`PreviousChannelId` in `MsgChannelOpenTry` has been deprecated and is no longer used by core IBC.
+
 ### ICS27 - Interchain Accounts
 
 The `RegisterInterchainAccount` API has been modified to include an additional `version` argument. This change has been made in order to support ICS29 fee middleware, for relayer incentivization of ICS27 packets.
@@ -91,3 +99,5 @@ if err := k.icaControllerKeeper.RegisterInterchainAccount(ctx, msg.ConnectionId,
 ## Relayers
 
 When using the `DenomTrace` gRPC, the full IBC denomination with the `ibc/` prefix may now be passed in.
+
+Crossing hello's are no longer supported by core IBC. The handshake should be completed in the logical 4 step process (INIT, TRY, ACK, CONFIRM).

From dbb9b0e46a56c548d65f2feac5bba79ec656df69 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Colin=20Axn=C3=A9r?=
 <25233464+colin-axner@users.noreply.github.com>
Date: Thu, 7 Jul 2022 13:26:22 +0200
Subject: [PATCH 7/9] remove unnecessary doc

---
 .../adr-006-02-client-refactor.md             | 40 -------------------
 1 file changed, 40 deletions(-)
 delete mode 100644 docs/architecture/adr-006-02-client-refactor.md

diff --git a/docs/architecture/adr-006-02-client-refactor.md b/docs/architecture/adr-006-02-client-refactor.md
deleted file mode 100644
index 55ff76544cb..00000000000
--- a/docs/architecture/adr-006-02-client-refactor.md
+++ /dev/null
@@ -1,40 +0,0 @@
-# ADR 006: 02-client refactor
-
-## Changelog
-* 18 May 2022: Initial Draft
-
-## Status
-
-Accepted
-
-## Context
-
-> This section contains all the context one needs to understand the current state, and why there is a problem. It should be as succinct as possible and introduce the high level idea behind the solution. 
-
-## Decision
-
-> This section explains all of the details of the proposed solution, including implementation details.
-It should also describe affects / corollary items that may need to be changed as a part of this.
-If the proposed change will be large, please also indicate a way to do the change to maximize ease of review.
-(e.g. the optimal split of things to do between separate PR's)
-
-## Consequences
-
-> This section describes the consequences, after applying the decision. All consequences should be summarized here, not just the "positive" ones.
-
-### Positive
-
-### Negative
-
-### Neutral
-
-## References
-
-The primary discussion which motivated these changes was documented in issue [#284](https://github.com/cosmos/ibc-go/issues/284).
-
-Issues:
-* {reference link}
-
-PRs:
-* {ref}
-

From c890576083b419c0b229199f7ab9921416113a78 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Colin=20Axn=C3=A9r?=
 <25233464+colin-axner@users.noreply.github.com>
Date: Thu, 7 Jul 2022 13:48:05 +0200
Subject: [PATCH 8/9] remove crossing hello notion from ChanOpenAck

---
 modules/core/04-channel/keeper/handshake.go      | 7 ++-----
 modules/core/04-channel/keeper/handshake_test.go | 2 +-
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/modules/core/04-channel/keeper/handshake.go b/modules/core/04-channel/keeper/handshake.go
index 579ae9a25f1..1d9cfd6382c 100644
--- a/modules/core/04-channel/keeper/handshake.go
+++ b/modules/core/04-channel/keeper/handshake.go
@@ -222,11 +222,8 @@ func (k Keeper) ChanOpenAck(
 		return sdkerrors.Wrapf(types.ErrChannelNotFound, "port ID (%s) channel ID (%s)", portID, channelID)
 	}
 
-	if !(channel.State == types.INIT || channel.State == types.TRYOPEN) {
-		return sdkerrors.Wrapf(
-			types.ErrInvalidChannelState,
-			"channel state should be INIT or TRYOPEN (got %s)", channel.State.String(),
-		)
+	if channel.State != types.INIT {
+		return sdkerrors.Wrapf(types.ErrInvalidChannelState, "channel state should be INIT (got %s)", channel.State.String())
 	}
 
 	if !k.scopedKeeper.AuthenticateCapability(ctx, chanCap, host.ChannelCapabilityPath(portID, channelID)) {
diff --git a/modules/core/04-channel/keeper/handshake_test.go b/modules/core/04-channel/keeper/handshake_test.go
index e8750f85b05..88ca88887b4 100644
--- a/modules/core/04-channel/keeper/handshake_test.go
+++ b/modules/core/04-channel/keeper/handshake_test.go
@@ -322,7 +322,7 @@ func (suite *KeeperTestSuite) TestChanOpenAck() {
 			channelCap = suite.chainA.GetChannelCapability(path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID)
 		}, true},
 		{"channel doesn't exist", func() {}, false},
-		{"channel state is not INIT or TRYOPEN", func() {
+		{"channel state is not INIT", func() {
 			// create fully open channels on both chains
 			suite.coordinator.Setup(path)
 			channelCap = suite.chainA.GetChannelCapability(path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID)

From 86d61ed5b1cf8858e85c624a2d10b9108836853b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Colin=20Axn=C3=A9r?=
 <25233464+colin-axner@users.noreply.github.com>
Date: Thu, 7 Jul 2022 13:52:22 +0200
Subject: [PATCH 9/9] apply review suggestions

---
 CHANGELOG.md                | 2 +-
 docs/migrations/v3-to-v4.md | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0de36fb4c9a..e1fdccd2092 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -43,6 +43,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### API Breaking
 
+* (modules/core/04-channel) [\#1317](https://github.com/cosmos/ibc-go/pull/1317) Remove crossing hellos from channel handshakes. The `PreviousChannelId` in `MsgChannelOpenTry` has been deprecated.  
 * (transfer) [\#1250](https://github.com/cosmos/ibc-go/pull/1250) Deprecate `GetTransferAccount` since the `transfer` module account is never used.
 * (channel) [\#1283](https://github.com/cosmos/ibc-go/pull/1283) The `OnChanOpenInit` application callback now returns a version string in line with the latest [spec changes](https://github.com/cosmos/ibc/pull/629).  
 * (modules/29-fee)[\#1338](https://github.com/cosmos/ibc-go/pull/1338) Renaming `Result` field in `IncentivizedAcknowledgement` to `AppAcknowledgement`.
@@ -62,7 +63,6 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (modules/core/04-channel) [\#1232](https://github.com/cosmos/ibc-go/pull/1232) Updating params on `NewPacketId` and moving to bottom of file.
 * (app/29-fee) [\#1305](https://github.com/cosmos/ibc-go/pull/1305) Change version string for fee module to `ics29-1`
 * (app/29-fee) [\#1341](https://github.com/cosmos/ibc-go/pull/1341) Check if the fee module is locked and if the fee module is enabled before refunding all fees
-* (modules/core/04-channel) [\#1317](https://github.com/cosmos/ibc-go/pull/1317) Remove corssing hellos from channel handshakes. The `PreviousChannelId` in `MsgChannelOpenTry` has been deprecated.  
 * (transfer) [\#1414](https://github.com/cosmos/ibc-go/pull/1414) Emitting Sender address from `fungible_token_packet` events in `OnRecvPacket` and `OnAcknowledgementPacket`.
 * (testing/simapp) [\#1397](https://github.com/cosmos/ibc-go/pull/1397) Adding mock module to maccperms and adding check to ensure mock module is not a blocked account address. 
 * (core/02-client) [\#1570](https://github.com/cosmos/ibc-go/pull/1570) Emitting an event when handling an upgrade client proposal. 
diff --git a/docs/migrations/v3-to-v4.md b/docs/migrations/v3-to-v4.md
index 4fffedc9399..9d6a1fb3f31 100644
--- a/docs/migrations/v3-to-v4.md
+++ b/docs/migrations/v3-to-v4.md
@@ -100,4 +100,4 @@ if err := k.icaControllerKeeper.RegisterInterchainAccount(ctx, msg.ConnectionId,
 
 When using the `DenomTrace` gRPC, the full IBC denomination with the `ibc/` prefix may now be passed in.
 
-Crossing hello's are no longer supported by core IBC. The handshake should be completed in the logical 4 step process (INIT, TRY, ACK, CONFIRM).
+Crossing hellos are no longer supported by core IBC. The handshake should be completed in the logical 4 step process (INIT, TRY, ACK, CONFIRM).