MM-38016 Fix racy unit test (TestService_AddTopicListener) (#18207)

* remove CreateTestLogger API 
* add missing mockServer.Shutdown

shared/mlog/tlog.go

@@ -7,40 +7,17 @@ import (
 	"bytes"
 	"io"
 	"os"
-	"strings"
 	"sync"
-	"testing"
 
 	"github.com/mattermost/logr/v2"
 	"github.com/mattermost/logr/v2/formatters"
 	"github.com/mattermost/logr/v2/targets"
 )
 
-// CreateTestLogger creates a logger for unit tests, using the `TB.Log`
-func CreateTestLogger(tb testing.TB, writer io.Writer, levels ...Level) *Logger {
-	logger, _ := NewLogger()
-
-	filter := logr.NewCustomFilter(levels...)
-	formatter := &formatters.Plain{}
-
-	if tb != nil {
-		testtarget := newTestingTarget(tb)
-		if err := logger.log.Logr().AddTarget(testtarget, "_testTB", filter, formatter, 1000); err != nil {
-			tb.Fail()
-			return nil
-		}
-	}
-
-	if writer != nil {
-		target := targets.NewWriterTarget(writer)
-		if err := logger.log.Logr().AddTarget(target, "_testWriter", filter, formatter, 1000); err != nil {
-			tb.Fail()
-			return nil
-		}
-	}
-	return logger
-}
-
+// AddWriterTarget adds a simple io.Writer target to an existing Logger.
+// The `io.Writer` can be a buffer which is useful for testing.
+// When adding a buffer to collect logs make sure to use `mlog.Buffer` which is
+// a thread safe version of `bytes.Buffer`.
 func AddWriterTarget(logger *Logger, w io.Writer, useJSON bool, levels ...Level) error {
 	filter := logr.NewCustomFilter(levels...)
 
@@ -79,45 +56,6 @@ func CreateConsoleTestLogger(useJSON bool, level Level) *Logger {
 	return logger
 }
 
-// testingTarget is a simple log target that writes to the testing log.
-type testingTarget struct {
-	mux sync.Mutex
-	tb  testing.TB
-}
-
-func newTestingTarget(tb testing.TB) *testingTarget {
-	return &testingTarget{
-		tb: tb,
-	}
-}
-
-// Init is called once to initialize the target.
-func (tt *testingTarget) Init() error {
-	return nil
-}
-
-// Write outputs bytes to this file target.
-func (tt *testingTarget) Write(p []byte, rec *logr.LogRec) (int, error) {
-	tt.mux.Lock()
-	defer tt.mux.Unlock()
-
-	if tt.tb != nil {
-		tt.tb.Helper()
-		tt.tb.Log(strings.TrimSpace(string(p)))
-	}
-	return len(p), nil
-}
-
-// Shutdown is called once to free/close any resources.
-// Target queue is already drained when this is called.
-func (tt *testingTarget) Shutdown() error {
-	tt.mux.Lock()
-	defer tt.mux.Unlock()
-
-	tt.tb = nil
-	return nil
-}
-
 // Buffer provides a thread-safe buffer useful for logging to memory in unit tests.
 type Buffer struct {
 	buf bytes.Buffer