operation   func()
		labelValues []string
		wantCount   uint64
	}{
		{
			name: "encrypt",
			operation: func() {
				if _, err = service.Encrypt(ctx, "1", []byte("test data")); err != nil {
					t.Fatalf("failed when execute encrypt, error: %v", err)
				}
			},
			labelValues: []string{testProviderName, "/v2.KeyManagementService/Encrypt", "OK"},
			wantCount:   1,
		},
		{
			name: "decrypt",

			// Checking default binding.
			if wantBound := test.wantBinderID == -1; defaultBound != wantBound {
				t.Errorf("got bound with default binding: %v, want %v", defaultBound, wantBound)
			}

			// Checking extenders binding.
			for i, ext := range test.extenders {
				wantBound := i == test.wantBinderID
				if gotBound := ext.(*fakeExtender).gotBind; gotBound != wantBound {