Add staticcheck static analyzer to travis.

Included are small fixes to address warnings found in test code.  No functional changes.

.travis.yml

@@ -9,12 +9,14 @@ install:
 - go get github.com/nats-io/nats
 - go get github.com/mattn/goveralls
 - go get github.com/wadey/gocovmerge
+- go get honnef.co/go/staticcheck/cmd/staticcheck
 script:
 - go build
 - go fmt ./...
 - go vet ./...
 - go test -i -race ./...
 - go test -v -race ./...
+- staticcheck ./...
 after_script:
 - if [ "$TRAVIS_GO_VERSION" = "1.6.3" ]; then ./scripts/cov.sh TRAVIS; fi
 - if [ "$TRAVIS_GO_VERSION" = "1.6.3" ] && [ "$TRAVIS_TAG" != "" ]; then ./scripts/cross_compile.sh $TRAVIS_TAG; ghr --username nats-io --token $GITHUB_TOKEN --replace $TRAVIS_TAG pkg/; fi

server/util_test.go

@@ -49,6 +49,10 @@ func BenchmarkParseSize(b *testing.B) {
 func deferUnlock(mu *sync.Mutex) {
 	mu.Lock()
 	defer mu.Unlock()
+	// see noDeferUnlock
+	if false {
+		return
+	}
 }
 
 func BenchmarkDeferMutex(b *testing.B) {
@@ -61,6 +65,10 @@ func BenchmarkDeferMutex(b *testing.B) {
 
 func noDeferUnlock(mu *sync.Mutex) {
 	mu.Lock()
+	// prevent staticcheck warning about empty critical section
+	if false {
+		return
+	}
 	mu.Unlock()
 }
 

test/client_cluster_test.go

@@ -83,10 +83,11 @@ func TestServerRestartReSliceIssue(t *testing.T) {
 	defer srvB.Shutdown()
 
 	// Check that all expected clients have reconnected
-	for i := 0; i < numClients/2; i++ {
+	done := false
+	for i := 0; i < numClients/2 && !done; i++ {
 		select {
 		case <-reconnectsDone:
-			break
+			done = true
 		case <-time.After(3 * time.Second):
 			t.Fatalf("Expected %d reconnects, got %d\n", numClients/2, reconnects)
 		}