sdk/agent: add a first happy path test (#255)

Add a first happy path test that exercises two agents that are connected to each other and successfully open, pay, and close.

The agent code was ported over from the console example. The console example was really written to be throw away code, but the agent code within it was well formed enough to be something to build on. It's important we add tests early for the agent before we build too much more into it. This is a first step to closing #225.

sdk/agent/agent.go

@@ -254,20 +254,26 @@ func (a *Agent) Close() error {
 	return nil
 }
 
-func (a *Agent) loop() {
-	var err error
+func (a *Agent) receive() error {
 	recv := msg.NewDecoder(io.TeeReader(a.conn, a.LogWriter))
 	send := msg.NewEncoder(io.MultiWriter(a.conn, a.LogWriter))
+	m := msg.Message{}
+	err := recv.Decode(&m)
+	if err != nil {
+		return fmt.Errorf("reading and decoding: %v\n", err)
+	}
+	err = a.handle(m, send)
+	if err != nil {
+		return fmt.Errorf("handling message: %v\n", err)
+	}
+	return nil
+}
+
+func (a *Agent) receiveLoop() {
 	for {
-		m := msg.Message{}
-		err = recv.Decode(&m)
-		if err != nil {
-			fmt.Fprintf(a.LogWriter, "error reading: %v\n", err)
-			break
-		}
-		err = a.handle(m, send)
+		err := a.receive()
 		if err != nil {
-			fmt.Fprintf(a.LogWriter, "error handling message: %v\n", err)
+			fmt.Fprintf(a.LogWriter, "error receiving: %v\n", err)
 		}
 	}
 }
@@ -276,11 +282,11 @@ func (a *Agent) handle(m msg.Message, send *msg.Encoder) error {
 	fmt.Fprintf(a.LogWriter, "handling %v\n", m.Type)
 	handler := handlerMap[m.Type]
 	if handler == nil {
-		return fmt.Errorf("unrecognized message type %v", m.Type)
+		return fmt.Errorf("handling message %d: unrecognized message type", m.Type)
 	}
 	err := handler(a, m, send)
 	if err != nil {
-		return fmt.Errorf("handling message type %v: %w", m.Type, err)
+		return fmt.Errorf("handling message %d: %w", m.Type, err)
 	}
 	return nil
 }

sdk/agent/agent_test.go

@@ -0,0 +1,170 @@
+package agent
+
+import (
+	"bytes"
+	"io"
+	"testing"
+	"time"
+
+	"github.com/stellar/experimental-payment-channels/sdk/state"
+	"github.com/stellar/go/keypair"
+	"github.com/stellar/go/network"
+	"github.com/stellar/go/txnbuild"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type sequenceNumberCollector func(accountID *keypair.FromAddress) (int64, error)
+
+func (f sequenceNumberCollector) GetSequenceNumber(accountID *keypair.FromAddress) (int64, error) {
+	return f(accountID)
+}
+
+type balanceCollectorFunc func(accountID *keypair.FromAddress, asset state.Asset) (int64, error)
+
+func (f balanceCollectorFunc) GetBalance(accountID *keypair.FromAddress, asset state.Asset) (int64, error) {
+	return f(accountID, asset)
+}
+
+type submitterFunc func(tx *txnbuild.Transaction) error
+
+func (f submitterFunc) SubmitTx(tx *txnbuild.Transaction) error {
+	return f(tx)
+}
+
+func TestAgent_openPaymentClose(t *testing.T) {
+	localEscrow := keypair.MustRandom()
+	localSigner := keypair.MustRandom()
+	remoteEscrow := keypair.MustRandom()
+	remoteSigner := keypair.MustRandom()
+
+	// Setup the local agent.
+	localVars := struct {
+		submittedTx *txnbuild.Transaction
+	}{}
+	localAgent := &Agent{
+		ObservationPeriodTime:      20 * time.Second,
+		ObservationPeriodLedgerGap: 1,
+		MaxOpenExpiry:              5 * time.Minute,
+		NetworkPassphrase:          network.TestNetworkPassphrase,
+		SequenceNumberCollector: sequenceNumberCollector(func(accountID *keypair.FromAddress) (int64, error) {
+			return 1, nil
+		}),
+		BalanceCollector: balanceCollectorFunc(func(accountID *keypair.FromAddress, asset state.Asset) (int64, error) {
+			return 100_0000000, nil
+		}),
+		Submitter: submitterFunc(func(tx *txnbuild.Transaction) error {
+			localVars.submittedTx = tx
+			return nil
+		}),
+		EscrowAccountKey:    localEscrow.FromAddress(),
+		EscrowAccountSigner: localSigner,
+		LogWriter:           io.Discard,
+	}
+
+	// Setup the remote agent.
+	remoteVars := struct {
+		submittedTx *txnbuild.Transaction
+	}{}
+	remoteAgent := &Agent{
+		ObservationPeriodTime:      20 * time.Second,
+		ObservationPeriodLedgerGap: 1,
+		MaxOpenExpiry:              5 * time.Minute,
+		NetworkPassphrase:          network.TestNetworkPassphrase,
+		SequenceNumberCollector: sequenceNumberCollector(func(accountID *keypair.FromAddress) (int64, error) {
+			return 1, nil
+		}),
+		BalanceCollector: balanceCollectorFunc(func(accountID *keypair.FromAddress, asset state.Asset) (int64, error) {
+			return 100_0000000, nil
+		}),
+		Submitter: submitterFunc(func(tx *txnbuild.Transaction) error {
+			remoteVars.submittedTx = tx
+			return nil
+		}),
+		EscrowAccountKey:    remoteEscrow.FromAddress(),
+		EscrowAccountSigner: remoteSigner,
+		LogWriter:           io.Discard,
+	}
+
+	// Connect the two agents.
+	type ReadWriter struct {
+		io.Reader
+		io.Writer
+	}
+	localMsgs := bytes.Buffer{}
+	remoteMsgs := bytes.Buffer{}
+	localAgent.conn = ReadWriter{
+		Reader: &remoteMsgs,
+		Writer: &localMsgs,
+	}
+	remoteAgent.conn = ReadWriter{
+		Reader: &localMsgs,
+		Writer: &remoteMsgs,
+	}
+	err := localAgent.hello()
+	require.NoError(t, err)
+	err = remoteAgent.receive()
+	require.NoError(t, err)
+	err = remoteAgent.hello()
+	require.NoError(t, err)
+	err = localAgent.receive()
+	require.NoError(t, err)
+
+	// Open the channel.
+	err = localAgent.Open()
+	require.NoError(t, err)
+	err = remoteAgent.receive()
+	require.NoError(t, err)
+	err = localAgent.receive()
+	require.NoError(t, err)
+
+	// Expect the open tx to have been submitted.
+	openTx, err := localAgent.channel.OpenTx()
+	require.NoError(t, err)
+	assert.Equal(t, openTx, localVars.submittedTx)
+	localVars.submittedTx = nil
+
+	// Make a payment.
+	err = localAgent.Payment("50.0")
+	require.NoError(t, err)
+	err = remoteAgent.receive()
+	require.NoError(t, err)
+	err = localAgent.receive()
+	require.NoError(t, err)
+
+	// Make another payment.
+	err = remoteAgent.Payment("20.0")
+	require.NoError(t, err)
+	err = localAgent.receive()
+	require.NoError(t, err)
+	err = remoteAgent.receive()
+	require.NoError(t, err)
+
+	// Expect no txs to have been submitted for payments.
+	assert.Nil(t, localVars.submittedTx)
+	assert.Nil(t, remoteVars.submittedTx)
+
+	// Declare the close, and start negotiating for an early close.
+	err = localAgent.DeclareClose()
+	require.NoError(t, err)
+
+	// Expect the declaration tx to have been submitted.
+	localDeclTx, _, err := localAgent.channel.CloseTxs()
+	require.NoError(t, err)
+	assert.Equal(t, localDeclTx, localVars.submittedTx)
+
+	// Receive the declaration at the remote and complete negotiation.
+	err = remoteAgent.receive()
+	require.NoError(t, err)
+	err = localAgent.receive()
+	require.NoError(t, err)
+
+	// Expect the close tx to have been submitted.
+	_, localCloseTx, err := localAgent.channel.CloseTxs()
+	require.NoError(t, err)
+	_, remoteCloseTx, err := remoteAgent.channel.CloseTxs()
+	require.NoError(t, err)
+	assert.Equal(t, localCloseTx, remoteCloseTx)
+	assert.Equal(t, localCloseTx, localVars.submittedTx)
+	assert.Equal(t, remoteCloseTx, remoteVars.submittedTx)
+}

sdk/agent/tcp.go

@@ -23,7 +23,7 @@ func (a *Agent) ServeTCP(addr string) error {
 	if err != nil {
 		return fmt.Errorf("sending hello: %w", err)
 	}
-	go a.loop()
+	go a.receiveLoop()
 	return nil
 }
 
@@ -42,6 +42,6 @@ func (a *Agent) ConnectTCP(addr string) error {
 	if err != nil {
 		return fmt.Errorf("sending hello: %w", err)
 	}
-	go a.loop()
+	go a.receiveLoop()
 	return nil
 }