test: add trace_test.go (#497)

* test: add trace_test.go

* refactor: rename test title

lambda/handlertrace/trace_test.go

@@ -0,0 +1,44 @@
+package handlertrace
+
+import (
+	"context"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTrace(t *testing.T) {
+	ctx := context.Background()
+
+	requestCall := 0
+	responseCall := 0
+
+	existedContext := context.WithValue(ctx, handlerTraceKey{}, HandlerTrace{
+		RequestEvent: func(ctx context.Context, event interface{}) {
+			requestCall += 1
+		},
+		ResponseEvent: func(ctx context.Context, event interface{}) {
+			responseCall += 1
+		},
+	})
+
+	trace := HandlerTrace{
+		RequestEvent: func(ctx context.Context, event interface{}) {
+			requestCall += 1
+		},
+		ResponseEvent: func(ctx context.Context, event interface{}) {
+			responseCall += 1
+		},
+	}
+
+	ctxWithTrace := NewContext(existedContext, trace)
+	traceFromCtx := FromContext(ctxWithTrace)
+
+	traceFromCtx.RequestEvent(ctxWithTrace, nil)
+	assert.Equal(t, requestCall, 2)
+
+	traceFromCtx.ResponseEvent(ctxWithTrace, nil)
+	fmt.Println(responseCall)
+	assert.Equal(t, responseCall, 2)
+}