Adds Generic Middleware helper functions (#383)

* add generic middleware helper functions

* Update modules/core/04-channel/types/version.go

Co-authored-by: colin axnér <25233464+colin-axner@users.noreply.github.com>

* remove app capability, add merge fn, changelog

* add back newline

Co-authored-by: colin axnér <25233464+colin-axner@users.noreply.github.com>

CHANGELOG.md

@@ -45,6 +45,8 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Improvements
 
+* [\#383](https://github.com/cosmos/ibc-go/pull/383) Adds helper functions for merging and splitting middleware versions from the underlying app version.
+
 ### Features
 
 * [\#384](https://github.com/cosmos/ibc-go/pull/384) Added `NegotiateAppVersion` method to `IBCModule` interface supported by a gRPC query service in `05-port`. This provides routing of requests to the desired application module callback, which in turn performs application version negotiation.

modules/core/04-channel/types/version.go

@@ -0,0 +1,27 @@
+package types
+
+import "strings"
+
+const ChannelVersionDelimiter = ":"
+
+// SplitChannelVersion splits the channel version string
+// into the outermost middleware version and the underlying app version.
+// It will use the default delimiter `:` for middleware versions.
+// In case there's no delimeter, this function returns an empty string for the middleware version (first return argument),
+// and the full input as the second underlying app version.
+func SplitChannelVersion(version string) (middlewareVersion, appVersion string) {
+	// only split out the first middleware version
+	splitVersions := strings.Split(version, ChannelVersionDelimiter)
+	if len(splitVersions) == 1 {
+		return "", version
+	}
+	middlewareVersion = splitVersions[0]
+	appVersion = strings.Join(splitVersions[1:], ChannelVersionDelimiter)
+	return
+}
+
+// MergeChannelVersions merges the provided versions together with the channel version delimiter
+// the versions should be passed in from the highest-level middleware to the base application
+func MergeChannelVersions(versions ...string) string {
+	return strings.Join(versions, ChannelVersionDelimiter)
+}

modules/core/04-channel/types/version_test.go

@@ -0,0 +1,77 @@
+package types_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/cosmos/ibc-go/v2/modules/core/04-channel/types"
+)
+
+func TestSplitVersions(t *testing.T) {
+	testCases := []struct {
+		name       string
+		version    string
+		mwVersion  string
+		appVersion string
+	}{
+		{
+			"single wrapped middleware",
+			"fee29-1:ics20-1",
+			"fee29-1",
+			"ics20-1",
+		},
+		{
+			"multiple wrapped middleware",
+			"fee29-1:whitelist:ics20-1",
+			"fee29-1",
+			"whitelist:ics20-1",
+		},
+		{
+			"no middleware",
+			"ics20-1",
+			"",
+			"ics20-1",
+		},
+	}
+
+	for _, tc := range testCases {
+		mwVersion, appVersion := types.SplitChannelVersion(tc.version)
+		require.Equal(t, tc.mwVersion, mwVersion, "middleware version is unexpected for case: %s", tc.name)
+		require.Equal(t, tc.appVersion, appVersion, "app version is unexpected for case: %s", tc.name)
+	}
+}
+
+func TestMergeVersions(t *testing.T) {
+	testCases := []struct {
+		name     string
+		versions []string
+		merged   string
+	}{
+		{
+			"single version",
+			[]string{"ics20-1"},
+			"ics20-1",
+		},
+		{
+			"empty version",
+			[]string{},
+			"",
+		},
+		{
+			"two versions",
+			[]string{"fee29-1", "ics20-1"},
+			"fee29-1:ics20-1",
+		},
+		{
+			"multiple versions",
+			[]string{"fee29-1", "whitelist", "ics20-1"},
+			"fee29-1:whitelist:ics20-1",
+		},
+	}
+
+	for _, tc := range testCases {
+		actual := types.MergeChannelVersions(tc.versions...)
+		require.Equal(t, tc.merged, actual, "merged versions string does not equal expected value")
+	}
+}