fix test race by only stubbing now where we need to

graphql/handler/apollotracing/tracer_test.go

@@ -6,6 +6,9 @@ import (
 	"net/http/httptest"
 	"strings"
 	"testing"
+	"time"
+
+	"github.com/99designs/gqlgen/graphql"
 
 	"github.com/99designs/gqlgen/graphql/handler/apollotracing"
 	"github.com/99designs/gqlgen/graphql/handler/extension"
@@ -18,6 +21,15 @@ import (
 )
 
 func TestApolloTracing(t *testing.T) {
+	now := time.Unix(0, 0)
+
+	graphql.Now = func() time.Time {
+		defer func() {
+			now = now.Add(100 * time.Nanosecond)
+		}()
+		return now
+	}
+
 	h := testserver.New()
 	h.AddTransport(transport.POST{})
 	h.Use(apollotracing.Tracer{})
@@ -54,6 +66,15 @@ func TestApolloTracing(t *testing.T) {
 }
 
 func TestApolloTracing_withFail(t *testing.T) {
+	now := time.Unix(0, 0)
+
+	graphql.Now = func() time.Time {
+		defer func() {
+			now = now.Add(100 * time.Nanosecond)
+		}()
+		return now
+	}
+
 	h := testserver.New()
 	h.AddTransport(transport.POST{})
 	h.Use(extension.AutomaticPersistedQuery{Cache: lru.New(100)})

graphql/handler/testserver/testserver.go

@@ -15,14 +15,6 @@ import (
 // a generated server, but it aims to be good enough to test the handler package without relying on codegen.
 func New() *TestServer {
 	next := make(chan struct{})
-	now := time.Unix(0, 0)
-
-	graphql.Now = func() time.Time {
-		defer func() {
-			now = now.Add(100 * time.Nanosecond)
-		}()
-		return now
-	}
 
 	schema := gqlparser.MustLoadSchema(&ast.Source{Input: `
 		type Query {