func (cfg *BuildCfg) fillDefaults() error {
	if cfg.Repo != nil && cfg.NilRepo {
		return errors.New("cannot set a repo and specify nilrepo at the same time")
	}

	if cfg.Repo == nil {
		var d ds.Datastore
		d = ds.NewMapDatastore()
		if cfg.NilRepo {
			d = ds.NewNullDatastore()
		}
		r, err := defaultRepo(dsync.MutexWrap(d))
		if err != nil {
			return err
		}
		cfg.Repo = r
	}

	if cfg.Routing == nil {
		cfg.Routing = DHTOption
	}

	if cfg.Host == nil {
		cfg.Host = DefaultHostOption
	}

	return nil
}

func TestPinRecursiveFail(t *testing.T) {
	ctx := context.Background()
	dstore := dssync.MutexWrap(ds.NewMapDatastore())
	bstore := blockstore.NewBlockstore(dstore)
	bserv := bs.New(bstore, offline.Exchange(bstore))
	dserv := mdag.NewDAGService(bserv)

	p := NewPinner(dstore, dserv)

	a, _ := randNode()
	b, _ := randNode()
	err := a.AddNodeLinkClean("child", b)
	if err != nil {
		t.Fatal(err)
	}

	// NOTE: This isnt a time based test, we expect the pin to fail
	mctx, _ := context.WithTimeout(ctx, time.Millisecond)
	err = p.Pin(mctx, a, true)
	if err == nil {
		t.Fatal("should have failed to pin here")
	}

	_, err = dserv.Add(b)
	if err != nil {
		t.Fatal(err)
	}

	// this one is time based... but shouldnt cause any issues
	mctx, _ = context.WithTimeout(ctx, time.Second)
	err = p.Pin(mctx, a, true)
	if err != nil {
		t.Fatal(err)
	}
}

func TestRoutingResolve(t *testing.T) {
	dstore := dssync.MutexWrap(ds.NewMapDatastore())
	serv := mockrouting.NewServer()
	id := testutil.RandIdentityOrFatal(t)
	d := serv.ClientWithDatastore(context.Background(), id, dstore)

	resolver := NewRoutingResolver(d, 0)
	publisher := NewRoutingPublisher(d, dstore)

	privk, pubk, err := testutil.RandTestKeyPair(512)
	if err != nil {
		t.Fatal(err)
	}

	h := path.FromString("/ipfs/QmZULkCELmmk5XNfCgTnCyFgAVxBRBXyDHGGMVoLFLiXEN")
	err = publisher.Publish(context.Background(), privk, h)
	if err != nil {
		t.Fatal(err)
	}

	pubkb, err := pubk.Bytes()
	if err != nil {
		t.Fatal(err)
	}

	pkhash := u.Hash(pubkb)
	res, err := resolver.Resolve(context.Background(), key.Key(pkhash).Pretty())
	if err != nil {
		t.Fatal(err)
	}

	if res != h {
		t.Fatal("Got back incorrect value.")
	}
}

func TestDuplicateSemantics(t *testing.T) {
	ctx := context.Background()
	dstore := dssync.MutexWrap(ds.NewMapDatastore())
	bstore := blockstore.NewBlockstore(dstore)
	bserv := bs.New(bstore, offline.Exchange(bstore))

	dserv := mdag.NewDAGService(bserv)

	// TODO does pinner need to share datastore with blockservice?
	p := NewPinner(dstore, dserv)

	a, _ := randNode()
	_, err := dserv.Add(a)
	if err != nil {
		t.Fatal(err)
	}

	// pin is recursively
	err = p.Pin(ctx, a, true)
	if err != nil {
		t.Fatal(err)
	}

	// pinning directly should fail
	err = p.Pin(ctx, a, false)
	if err == nil {
		t.Fatal("expected direct pin to fail")
	}

	// pinning recursively again should succeed
	err = p.Pin(ctx, a, true)
	if err != nil {
		t.Fatal(err)
	}
}

func getMockDagServ(t testing.TB) mdag.DAGService {
	dstore := ds.NewMapDatastore()
	tsds := sync.MutexWrap(dstore)
	bstore := blockstore.NewBlockstore(tsds)
	bserv := bs.New(bstore, offline.Exchange(bstore))
	return mdag.NewDAGService(bserv)
}

func runFileCattingWorker(ctx context.Context, n *core.IpfsNode) error {
	conf, err := config.Init(ioutil.Discard, *nBitsForKeypair)
	if err != nil {
		return err
	}

	r := &repo.Mock{
		D: ds2.CloserWrap(syncds.MutexWrap(datastore.NewMapDatastore())),
		C: *conf,
	}
	dummy, err := core.NewNode(ctx, &core.BuildCfg{
		Repo: r,
	})
	if err != nil {
		return err
	}

	errs := make(chan error)

	go func() {
		defer dummy.Close()
		var i int64 = 1
		for {
			buf := new(bytes.Buffer)
			if err := random.WritePseudoRandomBytes(sizeOfIthFile(i), buf, *seed); err != nil {
				errs <- err
			}
			// add to a dummy node to discover the key
			k, err := coreunix.Add(dummy, bytes.NewReader(buf.Bytes()))
			if err != nil {
				errs <- err
			}
			e := elog.EventBegin(ctx, "cat", logging.LoggableF(func() map[string]interface{} {
				return map[string]interface{}{
					"key":       k,
					"localPeer": n.Identity,
				}
			}))
			if r, err := coreunix.Cat(ctx, n, k); err != nil {
				e.Done()
				log.Printf("failed to cat file. seed: %d #%d key: %s err: %s", *seed, i, k, err)
			} else {
				log.Println("found file", "seed", *seed, "#", i, "key", k, "size", unit.Information(sizeOfIthFile(i)))
				io.Copy(ioutil.Discard, r)
				e.Done()
				log.Println("catted file", "seed", *seed, "#", i, "key", k, "size", unit.Information(sizeOfIthFile(i)))
				i++
			}
			time.Sleep(time.Second)
		}
	}()

	err = <-errs
	if err != nil {
		log.Fatal(err)
	}

	return nil
}

func newEngine(ctx context.Context, idStr string) peerAndEngine {
	return peerAndEngine{
		Peer: peer.ID(idStr),
		//Strategy: New(true),
		Engine: NewEngine(ctx,
			blockstore.NewBlockstore(dssync.MutexWrap(ds.NewMapDatastore()))),
	}
}

func TestReturnsErrorWhenSizeNegative(t *testing.T) {
	bs := NewBlockstore(syncds.MutexWrap(ds.NewMapDatastore()))
	_, err := WriteCached(bs, -1)
	if err != nil {
		return
	}
	t.Fail()
}

func getMockDagServAndBstore(t testing.TB) (mdag.DAGService, blockstore.GCBlockstore) {
	dstore := ds.NewMapDatastore()
	tsds := sync.MutexWrap(dstore)
	bstore := blockstore.NewBlockstore(tsds)
	bserv := bs.New(bstore, offline.Exchange(bstore))
	dserv := mdag.NewDAGService(bserv)
	return dserv, bstore
}

// NewPeerstore creates a threadsafe collection of peers.
func NewPeerstore() Peerstore {
	return &peerstore{
		keybook:     *newKeybook(),
		metrics:     *(NewMetrics()).(*metrics),
		AddrManager: AddrManager{},
		ds:          dssync.MutexWrap(ds.NewMapDatastore()),
	}
}

func TestMultisetRoundtrip(t *testing.T) {
	dstore := dssync.MutexWrap(datastore.NewMapDatastore())
	bstore := blockstore.NewBlockstore(dstore)
	bserv := blockservice.New(bstore, offline.Exchange(bstore))
	dag := merkledag.NewDAGService(bserv)

	fn := func(m map[key.Key]uint16) bool {
		// Generate a smaller range for refcounts than full uint64, as
		// otherwise this just becomes overly cpu heavy, splitting it
		// out into too many items. That means we need to convert to
		// the right kind of map. As storeMultiset mutates the map as
		// part of its bookkeeping, this is actually good.
		refcounts := copyMap(m)

		ctx := context.Background()
		n, err := storeMultiset(ctx, dag, refcounts, ignoreKeys)
		if err != nil {
			t.Fatalf("storing multiset: %v", err)
		}
		root := &merkledag.Node{}
		const linkName = "dummylink"
		if err := root.AddNodeLink(linkName, n); err != nil {
			t.Fatalf("adding link to root node: %v", err)
		}

		roundtrip, err := loadMultiset(ctx, dag, root, linkName, ignoreKeys)
		if err != nil {
			t.Fatalf("loading multiset: %v", err)
		}

		orig := copyMap(m)
		success := true
		for k, want := range orig {
			if got, ok := roundtrip[k]; ok {
				if got != want {
					success = false
					t.Logf("refcount changed: %v -> %v for %q", want, got, k)
				}
				delete(orig, k)
				delete(roundtrip, k)
			}
		}
		for k, v := range orig {
			success = false
			t.Logf("refcount missing: %v for %q", v, k)
		}
		for k, v := range roundtrip {
			success = false
			t.Logf("refcount extra: %v for %q", v, k)
		}
		return success
	}
	if err := quick.Check(fn, nil); err != nil {
		t.Fatal(err)
	}
}

func (rs *mocknetserver) ClientWithDatastore(ctx context.Context, p testutil.Identity, ds ds.Datastore) Client {

	// FIXME AddPeer doesn't appear to be idempotent

	host, err := rs.mn.AddPeer(p.PrivateKey(), p.Address())
	if err != nil {
		panic("FIXME")
	}
	return dht.NewDHT(ctx, host, sync.MutexWrap(ds))
}

func TestGetWhenKeyNotPresent(t *testing.T) {
	bs := NewBlockstore(ds_sync.MutexWrap(ds.NewMapDatastore()))
	_, err := bs.Get(key.Key("not present"))

	if err != nil {
		t.Log("As expected, block is not present")
		return
	}
	t.Fail()
}

func InitializeSupernodeNetwork(
	ctx context.Context,
	numServers, numClients int,
	conf testutil.LatencyConfig) ([]*core.IpfsNode, []*core.IpfsNode, error) {

	// create network
	mn := mocknet.New(ctx)

	mn.SetLinkDefaults(mocknet.LinkOptions{
		Latency:   conf.NetworkLatency,
		Bandwidth: math.MaxInt32,
	})

	routingDatastore := ds2.CloserWrap(syncds.MutexWrap(datastore.NewMapDatastore()))
	var servers []*core.IpfsNode
	for i := 0; i < numServers; i++ {
		bootstrap, err := core.NewNode(ctx, &core.BuildCfg{
			Online:  true,
			Host:    mock.MockHostOption(mn),
			Routing: corerouting.SupernodeServer(routingDatastore),
		})
		if err != nil {
			return nil, nil, err
		}
		servers = append(servers, bootstrap)
	}

	var bootstrapInfos []peer.PeerInfo
	for _, n := range servers {
		info := n.Peerstore.PeerInfo(n.PeerHost.ID())
		bootstrapInfos = append(bootstrapInfos, info)
	}

	var clients []*core.IpfsNode
	for i := 0; i < numClients; i++ {
		n, err := core.NewNode(ctx, &core.BuildCfg{
			Online:  true,
			Host:    mock.MockHostOption(mn),
			Routing: corerouting.SupernodeClient(bootstrapInfos...),
		})
		if err != nil {
			return nil, nil, err
		}
		clients = append(clients, n)
	}
	mn.LinkAll()

	bcfg := core.BootstrapConfigWithPeers(bootstrapInfos)
	for _, n := range clients {
		if err := n.Bootstrap(bcfg); err != nil {
			return nil, nil, err
		}
	}
	return servers, clients, nil
}

func getDagservAndPinner(t *testing.T) dagservAndPinner {
	db := dssync.MutexWrap(ds.NewMapDatastore())
	bs := bstore.NewBlockstore(db)
	blockserv := bserv.New(bs, offline.Exchange(bs))
	dserv := NewDAGService(blockserv)
	mpin := pin.NewPinner(db, dserv)
	return dagservAndPinner{
		ds: dserv,
		mp: mpin,
	}
}

func setupDHT(ctx context.Context, t *testing.T) *IpfsDHT {
	h := netutil.GenHostSwarm(t, ctx)

	dss := dssync.MutexWrap(ds.NewMapDatastore())
	d := NewDHT(ctx, h, dss)

	d.Validator["v"] = &record.ValidChecker{
		Func: func(key.Key, []byte) error {
			return nil
		},
		Sign: false,
	}
	return d
}

func TestValueTypeMismatch(t *testing.T) {
	block := blocks.NewBlock([]byte("some data"))

	datastore := ds.NewMapDatastore()
	k := BlockPrefix.Child(block.Key().DsKey())
	datastore.Put(k, "data that isn't a block!")

	blockstore := NewBlockstore(ds_sync.MutexWrap(datastore))

	_, err := blockstore.Get(block.Key())
	if err != ValueTypeMismatch {
		t.Fatal(err)
	}
}

// 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,
	}
}

func TestFlush(t *testing.T) {
	dstore := dssync.MutexWrap(ds.NewMapDatastore())
	bstore := blockstore.NewBlockstore(dstore)
	bserv := bs.New(bstore, offline.Exchange(bstore))

	dserv := mdag.NewDAGService(bserv)
	p := NewPinner(dstore, dserv)
	_, k := randNode()

	p.PinWithMode(k, Recursive)
	if err := p.Flush(); err != nil {
		t.Fatal(err)
	}
	assertPinned(t, p, k, "expected key to still be pinned")
}

func TestElideDuplicateWrite(t *testing.T) {
	cd := &callbackDatastore{f: func() {}, ds: ds.NewMapDatastore()}
	bs := NewBlockstore(syncds.MutexWrap(cd))
	cachedbs, err := WriteCached(bs, 1)
	if err != nil {
		t.Fatal(err)
	}

	b1 := blocks.NewBlock([]byte("foo"))

	cachedbs.Put(b1)
	cd.SetFunc(func() {
		t.Fatal("write hit the datastore")
	})
	cachedbs.Put(b1)
}