refactor use separate lock instead of having setTerm function

server.go

@@ -67,7 +67,6 @@ type Server interface {
 	LogPath() string
 	SnapshotPath(lastIndex uint64, lastTerm uint64) string
 	Term() uint64
-	setTerm(term uint64)
 	CommitIndex() uint64
 	VotedFor() string
 	MemberCount() int
@@ -260,13 +259,6 @@ func (s *server) Term() uint64 {
 	return s.currentTerm
 }
 
-// Set the current term of the server, for testing purpose.
-func (s *server) setTerm(term uint64) {
-	s.mutex.Lock()
-	defer s.mutex.Unlock()
-	s.currentTerm = term
-}
-
 // Retrieves the current commit index of the server.
 func (s *server) CommitIndex() uint64 {
 	s.log.mutex.RLock()

server_test.go

@@ -45,7 +45,10 @@ func TestServerRequestVoteDeniedForStaleTerm(t *testing.T) {
 		t.Fatalf("Server %s unable to join: %v", s.Name(), err)
 	}
 
-	s.(*server).setTerm(2)
+	s.(*server).mutex.Lock()
+	s.(*server).currentTerm = 2
+	s.(*server).mutex.Unlock()
+
 	defer s.Stop()
 	resp := s.RequestVote(newRequestVoteRequest(1, "foo", 1, 0))
 	if resp.Term != 2 || resp.VoteGranted {
@@ -65,7 +68,9 @@ func TestServerRequestVoteDeniedIfAlreadyVoted(t *testing.T) {
 		t.Fatalf("Server %s unable to join: %v", s.Name(), err)
 	}
 
-	s.(*server).setTerm(2)
+	s.(*server).mutex.Lock()
+	s.(*server).currentTerm = 2
+	s.(*server).mutex.Unlock()
 	defer s.Stop()
 	resp := s.RequestVote(newRequestVoteRequest(2, "foo", 1, 0))
 	if resp.Term != 2 || !resp.VoteGranted {
@@ -88,7 +93,9 @@ func TestServerRequestVoteApprovedIfAlreadyVotedInOlderTerm(t *testing.T) {
 
 	time.Sleep(time.Millisecond * 100)
 
-	s.(*server).setTerm(2)
+	s.(*server).mutex.Lock()
+	s.(*server).currentTerm = 2
+	s.(*server).mutex.Unlock()
 	defer s.Stop()
 	resp := s.RequestVote(newRequestVoteRequest(2, "foo", 2, 1))
 	if resp.Term != 2 || !resp.VoteGranted || s.VotedFor() != "foo" {
@@ -236,7 +243,9 @@ func TestServerAppendEntriesWithStaleTermsAreRejected(t *testing.T) {
 	s.Start()
 
 	defer s.Stop()
-	s.(*server).setTerm(2)
+	s.(*server).mutex.Lock()
+	s.(*server).currentTerm = 2
+	s.(*server).mutex.Unlock()
 
 	// Append single entry.
 	e, _ := newLogEntry(nil, 1, 1, &testCommand1{Val: "foo", I: 10})