Add image pull waiting.

Signed-off-by: Random-Liu <lantaol@google.com>

pkg/server/image_pull_test.go

@@ -17,6 +17,8 @@ limitations under the License.
 package server
 
 import (
+	"fmt"
+	"sync"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -72,3 +74,22 @@ func TestUpdateImageMetadata(t *testing.T) {
 		assert.Equal(t, test.expectedRepoDigests, m.RepoDigests)
 	}
 }
+
+func TestResources(t *testing.T) {
+	const threads = 10
+	var wg sync.WaitGroup
+	r := newResourceSet()
+	for i := 0; i < threads; i++ {
+		wg.Add(1)
+		go func(ref string) {
+			r.add(ref)
+			wg.Done()
+		}(fmt.Sprintf("sha256:%d", i))
+	}
+	wg.Wait()
+	refs := r.all()
+	for i := 0; i < threads; i++ {
+		_, ok := refs[fmt.Sprintf("sha256:%d", i)]
+		assert.True(t, ok)
+	}
+}