htlcswitch/switch test: add TestSwitchGetPaymentResult

TestSwitchGetPaymentResult tests that the switch interacts as expected
with the circuit map and network result store when looking up the result
of a payment ID. This is important for not to lose results under
concurrent lookup and receiving results.

htlcswitch/mock.go

@@ -916,3 +916,58 @@ func (m *mockNotifier) RegisterSpendNtfn(outpoint *wire.OutPoint, _ []byte,
 		Spend: make(chan *chainntnfs.SpendDetail),
 	}, nil
 }
+
+type mockCircuitMap struct {
+	lookup chan *PaymentCircuit
+}
+
+var _ CircuitMap = (*mockCircuitMap)(nil)
+
+func (m *mockCircuitMap) OpenCircuits(...Keystone) error {
+	return nil
+}
+
+func (m *mockCircuitMap) TrimOpenCircuits(chanID lnwire.ShortChannelID,
+	start uint64) error {
+	return nil
+}
+
+func (m *mockCircuitMap) DeleteCircuits(inKeys ...CircuitKey) error {
+	return nil
+}
+
+func (m *mockCircuitMap) CommitCircuits(
+	circuit ...*PaymentCircuit) (*CircuitFwdActions, error) {
+
+	return nil, nil
+}
+
+func (m *mockCircuitMap) CloseCircuit(outKey CircuitKey) (*PaymentCircuit,
+	error) {
+	return nil, nil
+}
+
+func (m *mockCircuitMap) FailCircuit(inKey CircuitKey) (*PaymentCircuit,
+	error) {
+	return nil, nil
+}
+
+func (m *mockCircuitMap) LookupCircuit(inKey CircuitKey) *PaymentCircuit {
+	return <-m.lookup
+}
+
+func (m *mockCircuitMap) LookupOpenCircuit(outKey CircuitKey) *PaymentCircuit {
+	return nil
+}
+
+func (m *mockCircuitMap) LookupByPaymentHash(hash [32]byte) []*PaymentCircuit {
+	return nil
+}
+
+func (m *mockCircuitMap) NumPending() int {
+	return 0
+}
+
+func (m *mockCircuitMap) NumOpen() int {
+	return 0
+}