test(spanner): move testing helper to a test (#5327)

Fixes: #5326

spanner/integration_test.go

@@ -37,9 +37,11 @@ import (
 	"cloud.google.com/go/civil"
 	"cloud.google.com/go/internal/testutil"
 	"cloud.google.com/go/internal/uid"
+	"cloud.google.com/go/internal/version"
 	database "cloud.google.com/go/spanner/admin/database/apiv1"
 	instance "cloud.google.com/go/spanner/admin/instance/apiv1"
 	"go.opencensus.io/stats/view"
+	"go.opencensus.io/tag"
 	"google.golang.org/api/iterator"
 	"google.golang.org/api/option"
 	adminpb "google.golang.org/genproto/googleapis/spanner/admin/database/v1"
@@ -3741,3 +3743,14 @@ func blackholeOrAllowDirectPath(t *testing.T, blackholeDP bool) {
 		t.Logf(string(out))
 	}
 }
+
+func checkCommonTagsGFELatency(t *testing.T, m map[tag.Key]string) {
+	// We only check prefix because client ID increases if we create
+	// multiple clients for the same database.
+	if !strings.HasPrefix(m[tagKeyClientID], "client") {
+		t.Fatalf("Incorrect client ID: %v", m[tagKeyClientID])
+	}
+	if m[tagKeyLibVersion] != version.Repo {
+		t.Fatalf("Incorrect library version: %v", m[tagKeyLibVersion])
+	}
+}

spanner/stats.go

@@ -19,7 +19,6 @@ import (
 	"strconv"
 	"strings"
 	"sync"
-	"testing"
 
 	"cloud.google.com/go/internal/version"
 	"go.opencensus.io/stats"
@@ -276,17 +275,6 @@ func captureGFELatencyStats(ctx context.Context, md metadata.MD, keyMethod strin
 	return nil
 }
 
-func checkCommonTagsGFELatency(t *testing.T, m map[tag.Key]string) {
-	// We only check prefix because client ID increases if we create
-	// multiple clients for the same database.
-	if !strings.HasPrefix(m[tagKeyClientID], "client") {
-		t.Fatalf("Incorrect client ID: %v", m[tagKeyClientID])
-	}
-	if m[tagKeyLibVersion] != version.Repo {
-		t.Fatalf("Incorrect library version: %v", m[tagKeyLibVersion])
-	}
-}
-
 func createContextAndCaptureGFELatencyMetrics(ctx context.Context, ct *commonTags, md metadata.MD, keyMethod string) error {
 	var ctxGFE, err = tag.New(ctx,
 		tag.Upsert(tagKeyClientID, ct.clientID),