test: split grab-bag test files into topical ones

Replace the coverage_extra{,2,3} and *_cover catch-all test files with files
named for what they cover: send_media, sticker_methods, builders, rich,
send_invoice, chat_photo, download, option_methods, send_action, edit_media,
convert_message, dispatch, inline_passport. Media-group, peer-ref and
entities tests fold into their existing topical files; the shared sendMediaOK
helper moves to the harness. No behaviour change.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: ernado

builders_test.go

@@ -0,0 +1,29 @@
+package botapi
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestBuilders(t *testing.T) {
+	if kb := Keyboard(Row(Button("a"), ButtonContact("c")), Row(Button("b"))); len(kb.Keyboard) != 2 {
+		t.Fatalf("keyboard = %#v", kb)
+	}
+	if ik := InlineKeyboard([]InlineKeyboardButton{InlineButtonData("x", "d"), InlineButtonURL("u", "https://e")}); len(ik.InlineKeyboard) != 1 {
+		t.Fatalf("inline keyboard = %#v", ik)
+	}
+	for _, f := range []InputFile{
+		FileID("id"), FileURL("https://e"), FileFromPath("/tmp/x"),
+		FileFromBytes("n", []byte("d")), FileFromReader("n", bytes.NewReader(nil)),
+	} {
+		if f == nil {
+			t.Fatal("nil input file")
+		}
+	}
+	if e := Emoji("👍"); e == nil {
+		t.Fatal("nil emoji reaction")
+	}
+	if e := CustomEmoji("123"); e == nil {
+		t.Fatal("nil custom emoji reaction")
+	}
+}

chat_photo_test.go

@@ -0,0 +1,29 @@
+package botapi
+
+import (
+	"context"
+	"testing"
+
+	"github.com/gotd/td/tg"
+)
+
+func TestSetChatPhotoUpload(t *testing.T) {
+	inv := newMockInvoker()
+	inv.reply(tg.ChannelsEditPhotoRequestTypeID, okUpdates())
+	b := newMockBot(inv)
+
+	err := b.SetChatPhoto(context.Background(), tdlibChannel(50), FileFromBytes("p.jpg", []byte("img")))
+	if err != nil {
+		t.Fatalf("SetChatPhoto: %v", err)
+	}
+	if !inv.called(tg.ChannelsEditPhotoRequestTypeID) {
+		t.Fatal("expected channels.editPhoto")
+	}
+}
+
+func TestSetChatPhotoRejectsNonUpload(t *testing.T) {
+	b := newMockBot(newMockInvoker())
+	if err := b.SetChatPhoto(context.Background(), tdlibChannel(50), FileID("x")); err == nil {
+		t.Fatal("SetChatPhoto should reject a non-uploaded file")
+	}
+}