// client were reached.
func ReachedClusters(allClusters cluster.Clusters, expectedClusters cluster.Clusters) echo.Checker {
	expectedByNetwork := expectedClusters.ByNetwork()
	return func(result echo.CallResult, err error) error {
		return checkReachedClusters(result, allClusters, expectedByNetwork)
	}
}

// ReachedSourceCluster is similar to ReachedClusters, except it only checks the reachability of source cluster only

								// that selector helps us verify that we reached the endpoints due to the WorkloadEntry and not regular multicluster service discovery
								Check:                   check.ReachedClusters(t.Clusters(), apps.A.Clusters().Configs()),
								Address:                 "serviceentry.mesh.global",
								Port:                    ports.HTTP,
								Scheme:                  scheme.HTTP,

												opts.Check = check.And(opts.Check, check.ReachedSourceCluster(t.Clusters()))
											} else {
												opts.Check = check.And(opts.Check, check.ReachedClusters(t.Clusters(), expectedClusters))
											}
										} else {
											// Expect to stay in the same cluster as the source pod.
											expectedClusters := cluster.Clusters{from.Config().Cluster}

							source.CallOrFail(t, echo.CallOptions{
								To: to,
								Port: echo.Port{
									Name: "http",
								},
								Check: check.And(
									check.OK(),
									check.ReachedClusters(t.AllClusters(), cluster.Clusters{source.Config().Cluster}),
								),
								Retry: echo.Retry{
									Options: []retry.Option{multiclusterRetryDelay, multiclusterRetryTimeout},
								},
							})

			Namespace: echos.Namespace.Name(),
		},
	}
}

func checkClustersReached(allClusters cluster.Clusters, clusters cluster.Clusters) echo.Checker {
	return check.And(
		check.OK(),
		check.ReachedClusters(allClusters, clusters))
}

func checkDNSLookupFailed() echo.Checker {
	return check.And(
		check.Error(),
		func(_ echo.CallResult, err error) error {

      - backend:
          service:
            name: b
            port:
              number: 80
        path: %s
        pathType: Prefix
`

			successChecker := check.And(check.OK(), check.ReachedClusters(t.AllClusters(), apps.B.Clusters()))
			failureChecker := check.Status(http.StatusNotFound)
			count := 2 * t.Clusters().Len()

			// TODO check all clusters were hit
			cases := []struct {
				name       string

								// See https://github.com/istio/istio/issues/32208 for details
								// We want to skip this for requests from the cross-network pod
								if err := check.ReachedClusters(t.AllClusters(), toClusters).Check(echo.CallResult{
									From:      result.From,
									Opts:      result.Opts,
									Responses: hostResponses,
								}, nil); err != nil {