streamdata: edit metadata

This edits metadata in a robust way.

Signed-off-by: Yonah <contrib@gensokyo.uk>

streamdata_test.go

@@ -356,6 +356,28 @@ func TestChannel(t *testing.T) {
 		t.Errorf("(rf) Add: %#v", data)
 	}
 
+	wantVODEdit := streamdata.VOD{
+		Title:    "edit\x00",
+		Date:     time.Unix(0xdeadbeef, 0).UTC(),
+		Category: "\t\x00",
+		Mirror:   "https://satori.hifuu.internal/edit.mp4\x00",
+	}
+	if err := c.Edit(&streamdata.Ident{Channel: 0xcafe}, func(v *streamdata.VOD) error {
+		if *v != (streamdata.VOD{}) {
+			t.Errorf("Edit: v = %#v", v)
+		}
+
+		*v = wantVODEdit
+		return nil
+	}); err != nil {
+		t.Fatalf("Edit: error = %v", err)
+	}
+	if gotVODEdit, err := c.Load(&streamdata.Ident{Channel: 0xcafe}); err != nil {
+		t.Fatalf("(edit) Load: error = %v", err)
+	} else if *gotVODEdit != wantVODEdit {
+		t.Errorf("Edit: %#v, want %#v", *gotVODEdit, wantVODEdit)
+	}
+
 	if err := os.Chmod(path.Join(d, "vod", wantIdent), 0); err != nil {
 		t.Fatal(err)
 	}