test: add unixfs/reader tests for WriteTo and size

License: MIT
Signed-off-by: Jakub Sztandera <kubuxu@protonmail.ch>

unixfs/io/dagreader_test.go

 package io
 
 import (
+	"bytes"
 	"io/ioutil"
 	"os"
 	"strings"
@@ -197,6 +198,44 @@ func TestMetadataNode(t *testing.T) {
 	}
 }
 
+func TestWriteTo(t *testing.T) {
+	dserv := testu.GetDAGServ()
+	inbuf, node := testu.GetRandomNode(t, dserv, 1024)
+	ctx, closer := context.WithCancel(context.Background())
+	defer closer()
+
+	reader, err := NewDagReader(ctx, node, dserv)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	outbuf := new(bytes.Buffer)
+	reader.WriteTo(outbuf)
+
+	err = testu.ArrComp(inbuf, outbuf.Bytes())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+}
+
+func TestReaderSzie(t *testing.T) {
+	dserv := testu.GetDAGServ()
+	size := int64(1024)
+	_, node := testu.GetRandomNode(t, dserv, size)
+	ctx, closer := context.WithCancel(context.Background())
+	defer closer()
+
+	reader, err := NewDagReader(ctx, node, dserv)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if reader.Size() != uint64(size) {
+		t.Fatal("wrong reader size")
+	}
+}
+
 func readByte(t testing.TB, reader *DagReader) byte {
 	out := make([]byte, 1)
 	c, err := reader.Read(out)