accesslog: LockWriter (to lock unprotected writers) and Clock (for testing)

relative to: https://github.com/kataras/iris/issues/1601

middleware/accesslog/accesslog_test.go

@@ -0,0 +1,61 @@
+package accesslog
+
+import (
+	"bytes"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/kataras/iris/v12/context"
+	"github.com/kataras/iris/v12/core/memstore"
+)
+
+func TestAccessLogPrint_Simple(t *testing.T) {
+	t.Parallel()
+	const goroutinesN = 42
+
+	w := new(bytes.Buffer)
+	ac := New()
+	ac.Writer = w
+	ac.LockWriter = true
+	ac.Clock = TClock(time.Time{})
+
+	var (
+		expected string
+		wg       = new(sync.WaitGroup)
+	)
+
+	for i := 0; i < goroutinesN; i++ {
+		wg.Add(1)
+		expected += "0001-01-01 00:00:00|1s|GET|/path_value?url_query=url_query_value|path_param=path_param_value url_query=url_query_value custom=custom_value|200|Incoming|Outcoming|\n"
+
+		go func() {
+			defer wg.Done()
+
+			ac.Print(
+				nil,
+				1*time.Second,
+				ac.TimeFormat,
+				200,
+				"GET",
+				"/path_value?url_query=url_query_value",
+				"Incoming",
+				"Outcoming",
+				&context.RequestParams{
+					Store: []memstore.Entry{
+						{Key: "path_param", ValueRaw: "path_param_value"},
+					},
+				}, []memstore.StringEntry{
+					{Key: "url_query", Value: "url_query_value"},
+				}, []memstore.Entry{
+					{Key: "custom", ValueRaw: "custom_value"},
+				})
+		}()
+	}
+
+	wg.Wait()
+
+	if got := w.String(); expected != got {
+		t.Fatalf("expected printed result to be:\n'%s'\n\nbut got:\n'%s'", expected, got)
+	}
+}