update field (#8)

Reviewed-on: #8
Co-authored-by: andrey <andrey@4devs.io>
Co-committed-by: andrey <andrey@4devs.io>

field/encoder_json_test.go

@@ -0,0 +1,38 @@
+package field_test
+
+import (
+	"testing"
+
+	"gitoa.ru/go-4devs/log/field"
+	"gitoa.ru/go-4devs/log/internal/buffer"
+)
+
+func TestEncoderJSONAppendField_string(t *testing.T) {
+	t.Parallel()
+
+	const expect = `"array":["value","other"],"str":"value","nullableStr":"value","nullstr":null`
+
+	encode := field.NewEncoderJSON()
+
+	buf := buffer.New()
+	defer func() {
+		buf.Free()
+	}()
+
+	val := "value"
+	strs := field.Strings("array", val, "other")
+	*buf = encode.AppendField(*buf, strs)
+
+	str := field.String("str", val)
+	*buf = encode.AppendField(*buf, str)
+
+	strp := field.Stringp("nullableStr", &val)
+	*buf = encode.AppendField(*buf, strp)
+
+	nullStr := field.Stringp("nullstr", nil)
+	*buf = encode.AppendField(*buf, nullStr)
+
+	if buf.String() != expect {
+		t.Errorf("json string expect:%v got:%s", expect, buf)
+	}
+}