etcd: add SequenceKey function

kvdb/etcd/bucket.go

@@ -130,3 +130,10 @@ func ValueKey(key string, buckets ...string) string {
 
 	return string(makeValueKey(bucket, []byte(key)))
 }
+
+// SequenceKey is a helper function used in tests or external tools to create a
+// sequence key from the passed bucket list.
+func SequenceKey(buckets ...string) string {
+	id := makeBucketID([]byte(BucketKey(buckets...)))
+	return string(makeSequenceKey(id[:]))
+}

kvdb/etcd/bucket_test.go

@@ -0,0 +1,34 @@
+//go:build kvdb_etcd
+// +build kvdb_etcd
+
+package etcd
+
+import (
+	"crypto/sha256"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+// TestBucketKey tests that a key for a bucket can be created correctly.
+func TestBucketKey(t *testing.T) {
+	rootID := sha256.Sum256([]byte("@"))
+	key := append(rootID[:], []byte("foo")...)
+	key = append(key, 0xff)
+	require.Equal(t, string(key), BucketKey("foo"))
+}
+
+// TestBucketVal tests that a key for a bucket value can be created correctly.
+func TestBucketVal(t *testing.T) {
+	rootID := sha256.Sum256([]byte("@"))
+	key := append(rootID[:], []byte("foo")...)
+	key = append(key, 0xff)
+
+	keyID := sha256.Sum256(key)
+	require.Equal(t, string(keyID[:]), BucketVal("foo"))
+}
+
+// TestSequenceKey tests that a key for a sequence can be created correctly.
+func TestSequenceKey(t *testing.T) {
+	require.Contains(t, SequenceKey("foo", "bar", "baz"), "$seq$")
+}