func MocknetTestRepo(p peer.ID, h host.Host, conf testutil.LatencyConfig, routing core.RoutingOption) core.ConfigOption {
	return func(ctx context.Context) (*core.IpfsNode, error) {
		const kWriteCacheElems = 100
		const alwaysSendToPeer = true
		dsDelay := delay.Fixed(conf.BlockstoreLatency)
		r := &repo.Mock{
			D: ds2.CloserWrap(syncds.MutexWrap(ds2.WithDelay(datastore.NewMapDatastore(), dsDelay))),
		}
		ds := r.Datastore()

		n := &core.IpfsNode{
			Peerstore: h.Peerstore(),
			Repo:      r,
			PeerHost:  h,
			Identity:  p,
		}
		dhtt, err := routing(ctx, n.PeerHost, n.Repo.Datastore())
		if err != nil {
			return nil, err
		}

		bsn := bsnet.NewFromIpfsHost(h, dhtt)
		bstore, err := blockstore.WriteCached(blockstore.NewBlockstore(ds), kWriteCacheElems)
		if err != nil {
			return nil, err
		}
		exch := bitswap.New(ctx, p, bsn, bstore, alwaysSendToPeer)
		n.Blockstore = bstore
		n.Exchange = exch
		n.Routing = dhtt
		return n, nil
	}
}

func setupNode(ctx context.Context, n *IpfsNode, cfg *BuildCfg) error {
	// setup local peer ID (private key is loaded in online setup)
	if err := n.loadID(); err != nil {
		return err
	}

	var err error
	n.Blockstore, err = bstore.WriteCached(bstore.NewBlockstore(n.Repo.Datastore()), kSizeBlockstoreWriteCache)
	if err != nil {
		return err
	}

	if cfg.Online {
		do := setupDiscoveryOption(n.Repo.Config().Discovery)
		if err := n.startOnlineServices(ctx, cfg.Routing, cfg.Host, do); err != nil {
			return err
		}
	} else {
		n.Exchange = offline.Exchange(n.Blockstore)
	}

	n.Blocks = bserv.New(n.Blockstore, n.Exchange)
	n.DAG = dag.NewDAGService(n.Blocks)
	n.Pinning, err = pin.LoadPinner(n.Repo.Datastore(), n.DAG)
	if err != nil {
		// TODO: we should move towards only running 'NewPinner' explicity on
		// node init instead of implicitly here as a result of the pinner keys
		// not being found in the datastore.
		// this is kinda sketchy and could cause data loss
		n.Pinning = pin.NewPinner(n.Repo.Datastore(), n.DAG)
	}
	n.Resolver = &path.Resolver{DAG: n.DAG}

	return nil
}

// TODO refactor so maybeRouter isn't special-cased in this way
func standardWithRouting(r repo.Repo, online bool, routingOption RoutingOption, hostOption HostOption) ConfigOption {
	return func(ctx context.Context) (n *IpfsNode, err error) {
		// FIXME perform node construction in the main constructor so it isn't
		// necessary to perform this teardown in this scope.
		success := false
		defer func() {
			if !success && n != nil {
				n.teardown()
			}
		}()

		// TODO move as much of node initialization as possible into
		// NewIPFSNode. The larger these config options are, the harder it is
		// to test all node construction code paths.

		if r == nil {
			return nil, fmt.Errorf("repo required")
		}
		n = &IpfsNode{
			mode: func() mode {
				if online {
					return onlineMode
				}
				return offlineMode
			}(),
			Repo: r,
		}

		n.ctx = ctx
		n.proc = goprocessctx.WithContextAndTeardown(ctx, n.teardown)

		// setup Peerstore
		n.Peerstore = peer.NewPeerstore()

		// setup local peer ID (private key is loaded in online setup)
		if err := n.loadID(); err != nil {
			return nil, err
		}

		n.Blockstore, err = bstore.WriteCached(bstore.NewBlockstore(n.Repo.Datastore()), kSizeBlockstoreWriteCache)
		if err != nil {
			return nil, err
		}

		if online {
			do := setupDiscoveryOption(n.Repo.Config().Discovery)
			if err := n.startOnlineServices(ctx, routingOption, hostOption, do); err != nil {
				return nil, err
			}
		} else {
			n.Exchange = offline.Exchange(n.Blockstore)
		}

		success = true
		return n, nil
	}
}

// session creates a test bitswap session.
//
// NB: It's easy make mistakes by providing the same peer ID to two different
// sessions. To safeguard, use the SessionGenerator to generate sessions. It's
// just a much better idea.
func Session(ctx context.Context, net tn.Network, p testutil.Identity) Instance {
	bsdelay := delay.Fixed(0)
	const writeCacheElems = 100

	adapter := net.Adapter(p)
	dstore := ds_sync.MutexWrap(datastore2.WithDelay(ds.NewMapDatastore(), bsdelay))

	bstore, err := blockstore.WriteCached(blockstore.NewBlockstore(ds_sync.MutexWrap(dstore)), writeCacheElems)
	if err != nil {
		panic(err.Error()) // FIXME perhaps change signature and return error.
	}

	const alwaysSendToPeer = true

	bs := New(ctx, p.ID(), adapter, bstore, alwaysSendToPeer).(*Bitswap)

	return Instance{
		Peer:            p.ID(),
		Exchange:        bs,
		blockstore:      bstore,
		blockstoreDelay: bsdelay,
	}
}