Add io.Reader support

Co-Authored-By: Roman Kredentser <shareed2k@gmail.com>

ctx.go

@@ -826,6 +826,16 @@ func (ctx *Ctx) SendString(body string) {
 	ctx.Fasthttp.Response.SetBodyString(body)
 }
 
+// SendStream sets response body stream and optional body size
+func (ctx *Ctx) SendStream(stream io.Reader, size ...int) {
+	if len(size) > 0 && size[0] >= 0 {
+		ctx.Fasthttp.Response.SetBodyStream(stream, size[0])
+	} else {
+		ctx.Fasthttp.Response.SetBodyStream(stream, -1)
+		ctx.Set(HeaderContentLength, strconv.Itoa(len(ctx.Fasthttp.Response.Body())))
+	}
+}
+
 // Set sets the response’s HTTP header field to the specified key, value.
 func (ctx *Ctx) Set(key string, val string) {
 	ctx.Fasthttp.Response.Header.Set(key, val)
@@ -879,6 +889,9 @@ func (ctx *Ctx) Write(bodies ...interface{}) {
 			ctx.Fasthttp.Response.AppendBodyString(strconv.Itoa(body))
 		case bool:
 			ctx.Fasthttp.Response.AppendBodyString(strconv.FormatBool(body))
+		case io.Reader:
+			ctx.Fasthttp.Response.SetBodyStream(body, -1)
+			ctx.Set(HeaderContentLength, strconv.Itoa(len(ctx.Fasthttp.Response.Body())))
 		default:
 			ctx.Fasthttp.Response.AppendBodyString(fmt.Sprintf("%v", body))
 		}

ctx_test.go

@@ -8,6 +8,7 @@ package fiber
 // go test -run Test_Ctx
 
 import (
+	"bufio"
 	"bytes"
 	"fmt"
 	"io"
@@ -1063,6 +1064,25 @@ func Test_Ctx_SendString(t *testing.T) {
 	utils.AssertEqual(t, "Don't crash please", string(ctx.Fasthttp.Response.Body()))
 }
 
+// go test -run Test_Ctx_SendStream
+func Test_Ctx_SendStream(t *testing.T) {
+	t.Parallel()
+	app := New()
+	ctx := app.AcquireCtx(&fasthttp.RequestCtx{})
+	defer app.ReleaseCtx(ctx)
+
+	ctx.SendStream(bytes.NewReader([]byte("Don't crash please")))
+	utils.AssertEqual(t, "Don't crash please", string(ctx.Fasthttp.Response.Body()))
+
+	ctx.SendStream(bufio.NewReader(bytes.NewReader([]byte("Hello bufio"))))
+	utils.AssertEqual(t, "Hello bufio", string(ctx.Fasthttp.Response.Body()))
+
+	file, err := os.Open("./.github/index.html")
+	utils.AssertEqual(t, nil, err)
+	ctx.SendStream(bufio.NewReader(file))
+	utils.AssertEqual(t, "227", string(ctx.Fasthttp.Response.Header.Peek("Content-Length")))
+}
+
 // go test -run Test_Ctx_Set
 func Test_Ctx_Set(t *testing.T) {
 	t.Parallel()