test: add relative seek test to dagreader

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

unixfs/io/dagreader_test.go

@@ -50,22 +50,15 @@ func TestSeekAndRead(t *testing.T) {
 
 	for i := 255; i >= 0; i-- {
 		reader.Seek(int64(i), os.SEEK_SET)
-		out := make([]byte, 1)
 
 		if reader.Offset() != int64(i) {
 			t.Fatal("expected offset to be increased by one after read")
 		}
 
-		c, err := reader.Read(out)
-		if c != 1 {
-			t.Fatal("reader should have read just one byte")
-		}
-		if err != nil {
-			t.Fatal(err)
-		}
+		out := readByte(t, reader)
 
-		if int(out[0]) != i {
-			t.Fatalf("read %d at index %d, expected %d", out[0], i, i)
+		if int(out) != i {
+			t.Fatalf("read %d at index %d, expected %d", out, i, i)
 		}
 
 		if reader.Offset() != int64(i+1) {
@@ -73,3 +66,44 @@ func TestSeekAndRead(t *testing.T) {
 		}
 	}
 }
+
+func TestRelativeSeek(t *testing.T) {
+	dserv := testu.GetDAGServ()
+	ctx, closer := context.WithCancel(context.Background())
+	defer closer()
+
+	inbuf := make([]byte, 1024)
+
+	for i := 0; i < 256; i++ {
+		inbuf[i*4] = byte(i)
+	}
+	node := testu.GetNode(t, dserv, inbuf)
+
+	reader, err := NewDagReader(ctx, node, dserv)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for i := 0; i < 256; i++ {
+		out := readByte(t, reader)
+		if int(out) != i {
+			t.Fatalf("expected to read: %d at %d, read %d", i, reader.Offset(), out)
+		}
+		reader.Seek(3, os.SEEK_CUR)
+	}
+
+}
+
+func readByte(t testing.TB, reader *DagReader) byte {
+	out := make([]byte, 1)
+	c, err := reader.Read(out)
+
+	if c != 1 {
+		t.Fatal("reader should have read just one byte")
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return out[0]
+}