diff --git a/api/v1/lib/httpcli/httpsched/state.go b/api/v1/lib/httpcli/httpsched/state.go
index f65565c6..b64318f5 100644
--- a/api/v1/lib/httpcli/httpsched/state.go
+++ b/api/v1/lib/httpcli/httpsched/state.go
@@ -220,6 +220,10 @@ func doSubscribe(ctx context.Context, ci callerInternal, call *stateCall) (mesos
 }
 
 func mustSubscribe(ctx context.Context, state *state) phase {
+	return mustSubscribe0(ctx, state, doSubscribe)
+}
+
+func mustSubscribe0(ctx context.Context, state *state, doSubscribe func(context.Context, callerInternal, *stateCall) (string, context.CancelFunc)) phase {
 	// (a) validate call = SUBSCRIBE
 	if t := state.call.GetType(); t != scheduler.Call_SUBSCRIBE {
 		state.call.err = apierrors.CodeUnsubscribed.Error("httpsched: expected SUBSCRIBE instead of " + t.String())
diff --git a/api/v1/lib/httpcli/httpsched/state_test.go b/api/v1/lib/httpcli/httpsched/state_test.go
index 54a752c5..16601ee8 100644
--- a/api/v1/lib/httpcli/httpsched/state_test.go
+++ b/api/v1/lib/httpcli/httpsched/state_test.go
@@ -1,9 +1,12 @@
 package httpsched
 
 import (
+	"context"
 	"errors"
+	"sync"
 	"testing"
 
+	"github.com/mesos/mesos-go/api/v1/lib"
 	"github.com/mesos/mesos-go/api/v1/lib/encoding"
 	"github.com/mesos/mesos-go/api/v1/lib/extras/latch"
 	"github.com/mesos/mesos-go/api/v1/lib/scheduler"
@@ -53,3 +56,129 @@ func TestDisconnectionDecoder(t *testing.T) {
 		t.Error("disconnect func was not called")
 	}
 }
+
+func TestMustSubscribe(t *testing.T) {
+	subscribeCall := &scheduler.Call{Type: scheduler.Call_SUBSCRIBE}
+	type subscription struct {
+		resp   mesos.Response
+		cancel context.CancelFunc
+	}
+	newSubscription := func(err error) subscription {
+		closed := make(chan struct{})
+		var closeOnce sync.Once
+		cancel := func() { closeOnce.Do(func() { close(closed) }) }
+		resp := &mesos.ResponseWrapper{
+			Decoder: encoding.DecoderFunc(func(encoding.Unmarshaler) (_ error) {
+				if err == context.Canceled {
+					select {
+					case <-closed:
+						return err
+					default:
+						return
+					}
+				}
+				if err != nil {
+					return err
+				}
+				return
+			}),
+			Closer: mesos.CloseFunc(func() (_ error) { cancel(); return }),
+		}
+		return subscription{
+			cancel: cancel,
+			resp:   resp,
+		}
+	}
+	for ti, tc := range map[string]struct {
+		state    *state
+		streamID string
+		sub      subscription
+		un       encoding.Unmarshaler
+		//-- wants:
+		wantsDisconnected bool
+	}{
+		"<>": {
+			state:             &state{call: &stateCall{}},
+			sub:               subscription{cancel: func() {}},
+			wantsDisconnected: true,
+		},
+		"subFailed": {
+			state:             &state{call: &stateCall{Call: subscribeCall}},
+			sub:               subscription{cancel: func() {}},
+			wantsDisconnected: true,
+		},
+		"subWorkedDecoderCanceled": {
+			state: &state{
+				call:        &stateCall{Call: subscribeCall},
+				client:      &client{},
+				notifyQueue: make(chan Notification, 1)},
+			streamID: "1",
+			sub:      newSubscription(context.Canceled),
+			un:       &scheduler.Event{},
+			// response decoder will not return context canceled unless the disconnector has been invoked
+		},
+		"subWorkedDecoderDeadlineExceeded": {
+			state: &state{
+				call:        &stateCall{Call: subscribeCall},
+				client:      &client{},
+				notifyQueue: make(chan Notification, 1)},
+			streamID: "1",
+			sub:      newSubscription(context.DeadlineExceeded),
+		},
+		"subWorkedDecoderBadObject": {
+			state: &state{
+				call:        &stateCall{Call: subscribeCall},
+				client:      &client{},
+				notifyQueue: make(chan Notification, 1)},
+			streamID: "1",
+			sub:      newSubscription(nil),
+			un:       &scheduler.Call{},
+		},
+		"subWorkedDecoderSchedulerError": {
+			state: &state{
+				call:        &stateCall{Call: subscribeCall},
+				client:      &client{},
+				notifyQueue: make(chan Notification, 1)},
+			streamID: "1",
+			sub:      newSubscription(nil),
+			un:       &scheduler.Event{Type: scheduler.Event_ERROR},
+		},
+	} {
+		t.Run(ti, func(t *testing.T) {
+			p := mustSubscribe0(context.Background(), tc.state,
+				func(_ context.Context, _ callerInternal, cl *stateCall) (string, context.CancelFunc) {
+					cl.resp = tc.sub.resp
+					return tc.streamID, tc.sub.cancel
+				})
+			if tc.wantsDisconnected != p.isDisconnected() {
+				if tc.wantsDisconnected {
+					t.Fatal("unexpectedly disconnected")
+				}
+				t.Fatal("expected to be disconnected but was not")
+			}
+			if tc.wantsDisconnected {
+				return
+			}
+
+			// check that state disconnector() doesn't change the phase
+			tc.state.fn = p
+			tc.state.disconnector()
+			if tc.state.fn.isDisconnected() {
+				t.Fatal("disconnector() incorrectly transitioned phase to disconnected")
+			}
+			if tc.state.streamID != tc.streamID {
+				t.Fatalf("expected stream %q instead of %q", tc.streamID, tc.state.streamID)
+			}
+
+			// fake response whose decoder disconnects for various reasons
+			err := tc.state.call.resp.Decode(tc.un)
+			if _, ok := tc.un.(*scheduler.Event); err == nil && !ok {
+				t.Fatal("expected error but got none")
+			}
+			t.Log(err)
+			if !tc.state.fn.isDisconnected() {
+				t.Fatal("disconnector() incorrectly transitioned phase to disconnected")
+			}
+		})
+	}
+}