Fix: use distinct server IDs in each test case

to ensure no side effects between test cases all
using the same global stats collector.

psiphon/transferstats/transferstats_test.go

@@ -36,8 +36,11 @@ const (
 	_SERVER_ID = "myserverid"
 )
 
+var nextServerID = 0
+
 type StatsTestSuite struct {
 	suite.Suite
+	serverID   string
 	httpClient *http.Client
 }
 
@@ -47,9 +50,11 @@ func TestStatsTestSuite(t *testing.T) {
 
 func (suite *StatsTestSuite) SetupTest() {
 	re := make(Regexps, 0)
+	suite.serverID = fmt.Sprintf("%s-%d", _SERVER_ID, nextServerID)
+	nextServerID++
 	suite.httpClient = &http.Client{
 		Transport: &http.Transport{
-			Dial: makeStatsDialer(_SERVER_ID, &re),
+			Dial: makeStatsDialer(suite.serverID, &re),
 		},
 	}
 }
@@ -91,23 +96,20 @@ func (suite *StatsTestSuite) Test_StatsConn() {
 	resp, err = suite.httpClient.Get("https://example.org/index.html")
 	suite.Nil(err, "basic HTTPS requests should succeed")
 	resp.Body.Close()
-
-	// Clear out stats
-	_ = TakeOutStatsForServer(_SERVER_ID)
 }
 
 func (suite *StatsTestSuite) Test_TakeOutStatsForServer() {
 
 	zeroPayload := &AccumulatedStats{hostnameToStats: make(map[string]*hostStats)}
 
-	payload := TakeOutStatsForServer(_SERVER_ID)
+	payload := TakeOutStatsForServer(suite.serverID)
 	suite.Equal(payload, zeroPayload, "should get zero stats before any traffic")
 
 	resp, err := suite.httpClient.Get("http://example.com/index.html")
 	suite.Nil(err, "need successful http to proceed with tests")
 	resp.Body.Close()
 
-	payload = TakeOutStatsForServer(_SERVER_ID)
+	payload = TakeOutStatsForServer(suite.serverID)
 	suite.NotNil(payload, "should receive valid payload for valid server ID")
 
 	payloadJSON, err := json.Marshal(payload)
@@ -116,7 +118,7 @@ func (suite *StatsTestSuite) Test_TakeOutStatsForServer() {
 	suite.Nil(err, "payload JSON should parse successfully")
 
 	// After we retrieve the stats for a server, they should be cleared out of the tracked stats
-	payload = TakeOutStatsForServer(_SERVER_ID)
+	payload = TakeOutStatsForServer(suite.serverID)
 	suite.Equal(payload, zeroPayload, "after retrieving stats for a server, there should be zero stats (until more data goes through)")
 }
 
@@ -125,19 +127,19 @@ func (suite *StatsTestSuite) Test_PutBackStatsForServer() {
 	suite.Nil(err, "need successful http to proceed with tests")
 	resp.Body.Close()
 
-	payloadToPutBack := TakeOutStatsForServer(_SERVER_ID)
+	payloadToPutBack := TakeOutStatsForServer(suite.serverID)
 	suite.NotNil(payloadToPutBack, "should receive valid payload for valid server ID")
 
 	zeroPayload := &AccumulatedStats{hostnameToStats: make(map[string]*hostStats)}
 
-	payload := TakeOutStatsForServer(_SERVER_ID)
+	payload := TakeOutStatsForServer(suite.serverID)
 	suite.Equal(payload, zeroPayload, "should be zero stats after getting them")
 
-	PutBackStatsForServer(_SERVER_ID, payloadToPutBack)
+	PutBackStatsForServer(suite.serverID, payloadToPutBack)
 	// PutBack is asynchronous, so we'll need to wait a moment for it to do its thing
 	<-time.After(100 * time.Millisecond)
 
-	payload = TakeOutStatsForServer(_SERVER_ID)
+	payload = TakeOutStatsForServer(suite.serverID)
 	suite.NotEqual(payload, zeroPayload, "stats should be re-added after putting back")
 	suite.Equal(payload, payloadToPutBack, "stats should be the same as after the first retrieval")
 }
@@ -196,7 +198,7 @@ func (suite *StatsTestSuite) Test_Regex() {
 
 	suite.httpClient = &http.Client{
 		Transport: &http.Transport{
-			Dial: makeStatsDialer(_SERVER_ID, regexps),
+			Dial: makeStatsDialer(suite.serverID, regexps),
 		},
 	}
 
@@ -220,7 +222,7 @@ func (suite *StatsTestSuite) Test_Regex() {
 		suite.Nil(err)
 		resp.Body.Close()
 
-		payload := TakeOutStatsForServer(_SERVER_ID)
+		payload := TakeOutStatsForServer(suite.serverID)
 		suite.NotNil(payload, "should get stats because we made HTTP reqs; %s", scheme)
 
 		expectedHostnames := mapset.NewSet()
@@ -251,7 +253,7 @@ func (suite *StatsTestSuite) Test_getTLSHostname() {
 
 	// TODO: Talk to a local TCP server instead of spamming example.com
 
-	dialer := makeStatsDialer(_SERVER_ID, nil)
+	dialer := makeStatsDialer(suite.serverID, nil)
 
 	// Data too short
 	conn, err := dialer("tcp", "example.com:80")