Fix test race condition. (#58)

Successfully passed with `go test ./... -race -count=100`

Author: pboothe

caller.go

@@ -38,7 +38,9 @@ var (
 		Value:   "scamper",
 	}
 
+	// Variables to aid in testing of main()
 	ctx, cancel = context.WithCancel(context.Background())
+	logFatal    = log.Fatal
 )
 
 func init() {
@@ -56,6 +58,7 @@ func main() {
 	rtx.Must(os.MkdirAll(*outputPath, 0557), "Could not create data directory")
 
 	defer cancel()
+	wg := sync.WaitGroup{}
 
 	promSrv := prometheusx.MustServeMetrics()
 	defer promSrv.Shutdown(ctx)
@@ -71,9 +74,11 @@ func main() {
 			ControlSocket:    *scamperCtrlSocket,
 			ScamperTimeout:   *scamperTimeout,
 		}
+		wg.Add(1)
 		go func() {
 			daemon.MustStart(ctx)
 			cancel()
+			wg.Done()
 		}()
 		trace = daemon
 	case "paris-traceroute":
@@ -84,7 +89,6 @@ func main() {
 		}
 	}
 
-	wg := sync.WaitGroup{}
 	cache := ipcache.New(ctx, trace, *ipcache.IPCacheTimeout, *ipcache.IPCacheUpdatePeriod)
 
 	if *poll {
@@ -101,8 +105,7 @@ func main() {
 			}
 			wg.Done()
 		}(cache)
-	}
-	if *eventsocket.Filename != "" {
+	} else if *eventsocket.Filename != "" {
 		wg.Add(1)
 		go func() {
 			connCreator, err := connection.NewCreator()
@@ -111,6 +114,8 @@ func main() {
 			eventsocket.MustRun(ctx, *eventsocket.Filename, connListener)
 			wg.Done()
 		}()
+	} else {
+		logFatal("--poll was false but --tcpinfo.eventsocket was set to \"\". This is a nonsensical configuration.")
 	}
 	wg.Wait()
 }

caller_test.go

@@ -3,6 +3,8 @@ package main
 import (
 	"context"
 	"io/ioutil"
+	"log"
+	"os"
 	"testing"
 	"time"
 
@@ -21,13 +23,15 @@ func TestMetrics(t *testing.T) {
 func TestMain(t *testing.T) {
 	dir, err := ioutil.TempDir("", "TestMain")
 	rtx.Must(err, "Could not create temp dir")
+	defer os.RemoveAll(dir)
 
 	// Verify that main doesn't crash, and that it does exit when the context is canceled.
 	// TODO: verify more in this test.
 	*prometheusx.ListenAddress = ":0"
 	*scamperCtrlSocket = dir + "/scamper.sock"
 	*waitTime = time.Nanosecond // Run through the loop a few times.
 	*outputPath = dir
+	*poll = true
 	tracerType.Value = "scamper"
 	ctx, cancel = context.WithCancel(context.Background())
 	go func() {
@@ -40,13 +44,15 @@ func TestMain(t *testing.T) {
 func TestMainWithConnectionListener(t *testing.T) {
 	dir, err := ioutil.TempDir("", "TestMainWithConnectionListener")
 	rtx.Must(err, "Could not create temp dir")
+	defer os.RemoveAll(dir)
 	srv := eventsocket.New(dir + "/events.sock")
 	rtx.Must(srv.Listen(), "Could not start the empty server")
 
 	*prometheusx.ListenAddress = ":0"
 	*scamperCtrlSocket = dir + "/scamper.sock"
 	*eventsocket.Filename = dir + "/events.sock"
 	*outputPath = dir
+	*poll = false
 	tracerType.Value = "paris-traceroute"
 
 	ctx, cancel = context.WithCancel(context.Background())
@@ -57,3 +63,25 @@ func TestMainWithConnectionListener(t *testing.T) {
 	}()
 	main()
 }
+
+func TestMainWithBadArgs(t *testing.T) {
+	tracerType.Value = "paris-traceroute"
+	*eventsocket.Filename = ""
+	*outputPath = "/tmp/"
+	*poll = false
+
+	logFatal = func(_ ...interface{}) {
+		panic("testpanic")
+	}
+	defer func() {
+		logFatal = log.Fatal
+	}()
+	defer func() {
+		r := recover()
+		if r != "testpanic" {
+			t.Error("Should have had a panic called testpanic, not", r)
+		}
+	}()
+
+	main()
+}