(draft): telegram markdown v2 string builder

2026-04-30 13:56:36 +03:00
parent 269ccec007
commit 071fc2375e
34 changed files with 1227 additions and 385 deletions
@@ -0,0 +1,2 @@
+// Package tgmd provides small helpers for Telegram Markdown text.
+package tgmd
@@ -0,0 +1,295 @@
+package tgmd
+
+import (
+	"strings"
+	"time"
+
+	"git.scuroneko.dev/scuroneko/extypes"
+	"git.scuroneko.dev/scuroneko/laniakea/tgapi"
+)
+
+//TODO GoDoc, tests. Maybe escape Markdown v2
+
+// MessageBuilder builds Telegram message text with explicit message entities.
+// MessageBuilder is not safe for concurrent use.
+type MessageBuilder struct {
+	str      string
+	offset   int
+	entities extypes.Slice[tgapi.MessageEntity]
+
+	entries extypes.Slice[*MessageBuilderEntry]
+	isDirty bool
+}
+
+// NewMessageBuilder returns an empty MessageBuilder.
+func NewMessageBuilder() *MessageBuilder {
+	return &MessageBuilder{
+		entities: make([]tgapi.MessageEntity, 0),
+		entries:  make(extypes.Slice[*MessageBuilderEntry], 0),
+		isDirty:  false,
+	}
+}
+
+// String returns the built message text.
+func (b *MessageBuilder) String() string {
+	if b.isDirty {
+		b.update()
+	}
+	return b.str
+}
+
+// Entities returns a copy of the built message entities.
+func (b *MessageBuilder) Entities() []tgapi.MessageEntity {
+	if b.isDirty {
+		b.update()
+	}
+	return append([]tgapi.MessageEntity(nil), b.entities...)
+}
+
+func (b *MessageBuilder) Build() (string, []tgapi.MessageEntity) {
+	if b.isDirty {
+		b.update()
+	}
+	return b.str, append([]tgapi.MessageEntity(nil), b.entities...)
+}
+
+func (b *MessageBuilder) Reset() {
+	b.str = ""
+	b.offset = 0
+	b.entities = b.entities[:0]
+	b.entries = b.entries[:0]
+	b.isDirty = false
+}
+
+func (b *MessageBuilder) update() *MessageBuilder {
+	b.offset = 0
+
+	var textLen int
+	var entitiesLen int
+	for _, e := range b.entries {
+		textLen += len(e.text) // bytes, для Grow нормально
+		entitiesLen += len(e.entities)
+	}
+
+	b.entities = make(extypes.Slice[tgapi.MessageEntity], 0, entitiesLen)
+
+	var sb strings.Builder
+	sb.Grow(textLen)
+
+	for _, e := range b.entries {
+		sb.WriteString(e.text)
+
+		for _, entity := range e.entities {
+			entity.Offset += b.offset
+			b.entities = append(b.entities, entity)
+		}
+
+		b.offset += e.length
+	}
+
+	b.str = sb.String()
+	b.isDirty = false
+	return b
+}
+func (b *MessageBuilder) markDirty() {
+	b.isDirty = true
+}
+
+type MessageBuilderEntry struct {
+	text   string
+	length int
+
+	b        *MessageBuilder
+	entities extypes.Slice[tgapi.MessageEntity]
+}
+
+// Add appends plain text to the message and returns its entry for formatting.
+func (b *MessageBuilder) Add(text string) *MessageBuilderEntry {
+	e := &MessageBuilderEntry{
+		b:        b,
+		entities: make(extypes.Slice[tgapi.MessageEntity], 0),
+
+		text:   text,
+		length: telegramTextLen(text),
+	}
+	b.entries = b.entries.Push(e)
+	b.markDirty()
+
+	return e
+}
+
+func (e *MessageBuilderEntry) Mention() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityMention,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+
+func (e *MessageBuilderEntry) Hashtag() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityHashtag,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+
+func (e *MessageBuilderEntry) Cashtag() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityCashtag,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+
+func (e *MessageBuilderEntry) BotCommand() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityBotCommand,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+
+func (e *MessageBuilderEntry) Email() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityEmail,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+
+func (e *MessageBuilderEntry) Phone() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityPhoneNumber,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+func (e *MessageBuilderEntry) Bold() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityBold,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+func (e *MessageBuilderEntry) Italic() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityItalic,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+func (e *MessageBuilderEntry) Underline() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityUnderline,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+func (e *MessageBuilderEntry) Strikethrough() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityStrike,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+func (e *MessageBuilderEntry) Spoiler() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntitySpoiler,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+func (e *MessageBuilderEntry) Quote() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityBlockquote,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+func (e *MessageBuilderEntry) ExpandableQuote() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityExpandableBlockquote,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+func (e *MessageBuilderEntry) InlineCode() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityCode,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+func (e *MessageBuilderEntry) CodeBlock() *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityPre,
+		Offset: 0, Length: e.length,
+	})
+	return e
+}
+func (e *MessageBuilderEntry) CodeBlockWithLanguage(lang string) *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityPre,
+		Offset: 0, Length: e.length, Language: lang,
+	})
+	return e
+}
+func (e *MessageBuilderEntry) Link(url string) *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityTextLink,
+		Offset: 0, Length: e.length, URL: url,
+	})
+	return e
+}
+func (e *MessageBuilderEntry) TextMention(user *tgapi.User) *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityTextMention,
+		Offset: 0, Length: e.length, User: user,
+	})
+	return e
+}
+func (e *MessageBuilderEntry) CustomEmoji(emojiID string) *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityCustomEmoji,
+		Offset: 0, Length: e.length, CustomEmojiID: emojiID,
+	})
+	return e
+}
+func (e *MessageBuilderEntry) DateTime(time time.Time) *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityDateTime,
+		Offset: 0, Length: e.length, UnixTime: time.Unix(),
+	})
+	return e
+}
+func (e *MessageBuilderEntry) DateTimeFormat(time time.Time, format string) *MessageBuilderEntry {
+	e.addEntity(tgapi.MessageEntity{
+		Type:   tgapi.MessageEntityDateTime,
+		Offset: 0, Length: e.length,
+		UnixTime: time.Unix(), DateTimeFormat: format,
+	})
+	return e
+}
+
+func telegramTextLen(text string) int {
+	n := 0
+	for _, r := range text {
+		if r <= 0xFFFF {
+			n++
+		} else {
+			n += 2
+		}
+	}
+	return n
+}
+
+func (e *MessageBuilderEntry) addEntity(entity tgapi.MessageEntity) {
+	if entity.Length <= 0 {
+		return
+	}
+	e.entities = append(e.entities, entity)
+	if e.b != nil {
+		e.b.markDirty()
+	}
+}
@@ -0,0 +1,416 @@
+package tgmd
+
+import (
+	"reflect"
+	"testing"
+	"time"
+
+	"git.scuroneko.dev/scuroneko/laniakea/tgapi"
+)
+
+func TestMessageBuilder_BuildPlainText(t *testing.T) {
+	b := NewMessageBuilder()
+
+	b.Add("Hello")
+	b.Add(", ")
+	b.Add("world")
+
+	text, entities := b.Build()
+
+	if text != "Hello, world" {
+		t.Fatalf("text = %q, want %q", text, "Hello, world")
+	}
+
+	if len(entities) != 0 {
+		t.Fatalf("entities len = %d, want 0", len(entities))
+	}
+}
+
+func TestMessageBuilder_EntityOffsetsAreUTF16(t *testing.T) {
+	b := NewMessageBuilder()
+
+	b.Add("Hi ")
+	b.Add("👋") // 2 UTF-16 code units
+	b.Add(" ")
+	b.Add("world").Bold()
+
+	text, entities := b.Build()
+
+	if text != "Hi 👋 world" {
+		t.Fatalf("text = %q, want %q", text, "Hi 👋 world")
+	}
+
+	want := []tgapi.MessageEntity{
+		{
+			Type:   tgapi.MessageEntityBold,
+			Offset: 6, // H i space = 3, 👋 = 2, space = 1
+			Length: 5,
+		},
+	}
+
+	if !reflect.DeepEqual(entities, want) {
+		t.Fatalf("entities = %#v, want %#v", entities, want)
+	}
+}
+
+func TestMessageBuilder_EntityLengthIsUTF16(t *testing.T) {
+	b := NewMessageBuilder()
+
+	b.Add("👋").Bold()
+
+	text, entities := b.Build()
+
+	if text != "👋" {
+		t.Fatalf("text = %q, want %q", text, "👋")
+	}
+
+	want := []tgapi.MessageEntity{
+		{
+			Type:   tgapi.MessageEntityBold,
+			Offset: 0,
+			Length: 2,
+		},
+	}
+
+	if !reflect.DeepEqual(entities, want) {
+		t.Fatalf("entities = %#v, want %#v", entities, want)
+	}
+}
+
+func TestMessageBuilder_MultipleEntitiesOnSameEntry(t *testing.T) {
+	b := NewMessageBuilder()
+
+	b.Add("hello").Bold().Italic()
+
+	_, entities := b.Build()
+
+	want := []tgapi.MessageEntity{
+		{
+			Type:   tgapi.MessageEntityBold,
+			Offset: 0,
+			Length: 5,
+		},
+		{
+			Type:   tgapi.MessageEntityItalic,
+			Offset: 0,
+			Length: 5,
+		},
+	}
+
+	if !reflect.DeepEqual(entities, want) {
+		t.Fatalf("entities = %#v, want %#v", entities, want)
+	}
+}
+
+func TestMessageBuilder_DoesNotDuplicateAfterRepeatedReads(t *testing.T) {
+	b := NewMessageBuilder()
+
+	b.Add("hello").Bold()
+
+	text1 := b.String()
+	entities1 := b.Entities()
+
+	text2 := b.String()
+	entities2 := b.Entities()
+
+	if text1 != text2 {
+		t.Fatalf("texts differ: %q != %q", text1, text2)
+	}
+
+	if !reflect.DeepEqual(entities1, entities2) {
+		t.Fatalf("entities differ: %#v != %#v", entities1, entities2)
+	}
+
+	want := []tgapi.MessageEntity{
+		{
+			Type:   tgapi.MessageEntityBold,
+			Offset: 0,
+			Length: 5,
+		},
+	}
+
+	if !reflect.DeepEqual(entities2, want) {
+		t.Fatalf("entities = %#v, want %#v", entities2, want)
+	}
+}
+
+func TestMessageBuilder_AddEntityAfterStringMarksDirty(t *testing.T) {
+	b := NewMessageBuilder()
+
+	entry := b.Add("hello")
+
+	if got := b.String(); got != "hello" {
+		t.Fatalf("String() = %q, want %q", got, "hello")
+	}
+
+	entry.Bold()
+
+	entities := b.Entities()
+
+	want := []tgapi.MessageEntity{
+		{
+			Type:   tgapi.MessageEntityBold,
+			Offset: 0,
+			Length: 5,
+		},
+	}
+
+	if !reflect.DeepEqual(entities, want) {
+		t.Fatalf("entities = %#v, want %#v", entities, want)
+	}
+}
+
+func TestMessageBuilder_EntitiesReturnsCopy(t *testing.T) {
+	b := NewMessageBuilder()
+
+	b.Add("hello").Bold()
+
+	entities1 := b.Entities()
+	entities1[0].Offset = 999
+
+	entities2 := b.Entities()
+
+	if entities2[0].Offset != 0 {
+		t.Fatalf("Entities() did not return copy: offset = %d, want 0", entities2[0].Offset)
+	}
+}
+
+func TestMessageBuilder_BuildReturnsEntitiesCopy(t *testing.T) {
+	b := NewMessageBuilder()
+
+	b.Add("hello").Bold()
+
+	_, entities1 := b.Build()
+	entities1[0].Offset = 999
+
+	_, entities2 := b.Build()
+
+	if entities2[0].Offset != 0 {
+		t.Fatalf("Build() did not return entities copy: offset = %d, want 0", entities2[0].Offset)
+	}
+}
+
+func TestMessageBuilder_Reset(t *testing.T) {
+	b := NewMessageBuilder()
+
+	b.Add("hello").Bold()
+
+	if got := b.String(); got != "hello" {
+		t.Fatalf("String() before Reset = %q, want %q", got, "hello")
+	}
+
+	b.Reset()
+
+	text, entities := b.Build()
+
+	if text != "" {
+		t.Fatalf("text after Reset = %q, want empty", text)
+	}
+
+	if len(entities) != 0 {
+		t.Fatalf("entities len after Reset = %d, want 0", len(entities))
+	}
+
+	b.Add("world").Italic()
+
+	text, entities = b.Build()
+
+	if text != "world" {
+		t.Fatalf("text after reuse = %q, want %q", text, "world")
+	}
+
+	want := []tgapi.MessageEntity{
+		{
+			Type:   tgapi.MessageEntityItalic,
+			Offset: 0,
+			Length: 5,
+		},
+	}
+
+	if !reflect.DeepEqual(entities, want) {
+		t.Fatalf("entities after reuse = %#v, want %#v", entities, want)
+	}
+}
+
+func TestMessageBuilder_EmptyEntryDoesNotCreateEntity(t *testing.T) {
+	b := NewMessageBuilder()
+
+	b.Add("").Bold()
+	b.Add("x")
+
+	text, entities := b.Build()
+
+	if text != "x" {
+		t.Fatalf("text = %q, want %q", text, "x")
+	}
+
+	if len(entities) != 0 {
+		t.Fatalf("entities len = %d, want 0: %#v", len(entities), entities)
+	}
+}
+
+func TestMessageBuilder_Link(t *testing.T) {
+	b := NewMessageBuilder()
+
+	b.Add("OpenAI").Link("https://openai.com")
+
+	_, entities := b.Build()
+
+	want := []tgapi.MessageEntity{
+		{
+			Type:   tgapi.MessageEntityTextLink,
+			Offset: 0,
+			Length: 6,
+			URL:    "https://openai.com",
+		},
+	}
+
+	if !reflect.DeepEqual(entities, want) {
+		t.Fatalf("entities = %#v, want %#v", entities, want)
+	}
+}
+
+func TestMessageBuilder_CodeBlockWithLanguage(t *testing.T) {
+	b := NewMessageBuilder()
+
+	b.Add("fmt.Println(\"hi\")").CodeBlockWithLanguage("go")
+
+	_, entities := b.Build()
+
+	want := []tgapi.MessageEntity{
+		{
+			Type:     tgapi.MessageEntityPre,
+			Offset:   0,
+			Length:   17,
+			Language: "go",
+		},
+	}
+
+	if !reflect.DeepEqual(entities, want) {
+		t.Fatalf("entities = %#v, want %#v", entities, want)
+	}
+}
+
+func TestMessageBuilder_DateTimeFormat(t *testing.T) {
+	b := NewMessageBuilder()
+
+	ts := time.Unix(1772323200, 0)
+
+	b.Add("date").DateTimeFormat(ts, "MMMM d, yyyy")
+
+	_, entities := b.Build()
+
+	want := []tgapi.MessageEntity{
+		{
+			Type:           tgapi.MessageEntityDateTime,
+			Offset:         0,
+			Length:         4,
+			UnixTime:       1772323200,
+			DateTimeFormat: "MMMM d, yyyy",
+		},
+	}
+
+	if !reflect.DeepEqual(entities, want) {
+		t.Fatalf("entities = %#v, want %#v", entities, want)
+	}
+}
+
+func TestTelegramTextLen(t *testing.T) {
+	tests := []struct {
+		name string
+		text string
+		want int
+	}{
+		{
+			name: "ascii",
+			text: "hello",
+			want: 5,
+		},
+		{
+			name: "cyrillic",
+			text: "привет",
+			want: 6,
+		},
+		{
+			name: "emoji",
+			text: "👋",
+			want: 2,
+		},
+		{
+			name: "mixed",
+			text: "a👋b",
+			want: 4,
+		},
+		{
+			name: "zwj sequence",
+			text: "👨‍👩‍👧‍👦",
+			want: 11,
+		},
+		{
+			name: "flag",
+			text: "🇫🇮",
+			want: 4,
+		},
+		{
+			name: "variation selector",
+			text: "❤️",
+			want: 2,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := telegramTextLen(tt.text)
+			if got != tt.want {
+				t.Fatalf("telegramTextLen(%q) = %d, want %d", tt.text, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestMessageBuilder_SimpleEntityTypes(t *testing.T) {
+	tests := []struct {
+		name string
+		add  func(*MessageBuilderEntry)
+		want tgapi.MessageEntityType
+	}{
+		{"mention", func(e *MessageBuilderEntry) { e.Mention() }, tgapi.MessageEntityMention},
+		{"hashtag", func(e *MessageBuilderEntry) { e.Hashtag() }, tgapi.MessageEntityHashtag},
+		{"cashtag", func(e *MessageBuilderEntry) { e.Cashtag() }, tgapi.MessageEntityCashtag},
+		{"bot command", func(e *MessageBuilderEntry) { e.BotCommand() }, tgapi.MessageEntityBotCommand},
+		{"email", func(e *MessageBuilderEntry) { e.Email() }, tgapi.MessageEntityEmail},
+		{"phone", func(e *MessageBuilderEntry) { e.Phone() }, tgapi.MessageEntityPhoneNumber},
+		{"bold", func(e *MessageBuilderEntry) { e.Bold() }, tgapi.MessageEntityBold},
+		{"italic", func(e *MessageBuilderEntry) { e.Italic() }, tgapi.MessageEntityItalic},
+		{"underline", func(e *MessageBuilderEntry) { e.Underline() }, tgapi.MessageEntityUnderline},
+		{"strikethrough", func(e *MessageBuilderEntry) { e.Strikethrough() }, tgapi.MessageEntityStrike},
+		{"spoiler", func(e *MessageBuilderEntry) { e.Spoiler() }, tgapi.MessageEntitySpoiler},
+		{"quote", func(e *MessageBuilderEntry) { e.Quote() }, tgapi.MessageEntityBlockquote},
+		{"expandable quote", func(e *MessageBuilderEntry) { e.ExpandableQuote() }, tgapi.MessageEntityExpandableBlockquote},
+		{"inline code", func(e *MessageBuilderEntry) { e.InlineCode() }, tgapi.MessageEntityCode},
+		{"code block", func(e *MessageBuilderEntry) { e.CodeBlock() }, tgapi.MessageEntityPre},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			b := NewMessageBuilder()
+
+			e := b.Add("hello")
+			tt.add(e)
+
+			_, entities := b.Build()
+
+			want := []tgapi.MessageEntity{
+				{
+					Type:   tt.want,
+					Offset: 0,
+					Length: 5,
+				},
+			}
+
+			if !reflect.DeepEqual(entities, want) {
+				t.Fatalf("entities = %#v, want %#v", entities, want)
+			}
+		})
+	}
+}
@@ -0,0 +1,71 @@
+package tgmd
+
+import (
+	"strconv"
+	"strings"
+
+	"git.scuroneko.dev/scuroneko/laniakea"
+)
+
+// Helpers in this file generate Telegram MarkdownV2.
+// All user-provided text is escaped.
+
+// TODO Markdown v2 escaping. GoDoc and tests
+
+// WithBold returns s wrapped as bold Telegram Markdown text.
+func WithBold(s string) string {
+	return "*" + s + "*"
+}
+
+// WithItalic returns s wrapped as italic Telegram Markdown text.
+func WithItalic(s string) string {
+	return "_" + s + "_"
+}
+
+func WithUnderline(s string) string {
+	return "__" + s + "__"
+}
+func WithStrikethrough(s string) string {
+	return "~" + s + "~"
+}
+func WithSpoiler(s string) string {
+	return "||" + s + "||"
+}
+
+// WithLink returns a Telegram Markdown link for text and URL.
+func WithLink(text, url string) string {
+	return "[" + text + "](" + url + ")"
+}
+
+func WithMention(text string, userID uint64) string {
+	return "[" + text + "](tg://user?id=" + strconv.FormatUint(userID, 10) + ")"
+}
+func WithEmoji(text, emojiID string) string {
+	return "[" + text + "](tg://emoji?id=" + emojiID + ")"
+}
+
+func WithTime(text string, unix uint64) string {
+	return "![" + text + "](tg://time?unix=" + strconv.FormatUint(unix, 10) + ")"
+}
+func WithTimeFormat(text string, unix uint64, format string) string {
+	return "![" + text + "](tg://time?unix=" +
+		strconv.FormatUint(unix, 10) +
+		"&format=" + format + ")"
+}
+
+// WithInlineCode returns s wrapped as inline code Telegram Markdown text.
+func WithInlineCode(s string) string {
+	return "`" + s + "`"
+}
+func WithBlockCode(s string) string {
+	return "```\n" + s + "\n```"
+}
+func WithBlockCodeLanguage(s, lang string) string {
+	return "```" + lang + "\n" + s + "\n```"
+}
+func WithQuote(s string) string {
+	return ">" + strings.ReplaceAll(laniakea.EscapeMarkdownV2(s), "\n", "\n>")
+}
+func WithQuoteExpandable(s string) string {
+	return "**>" + s
+}
@@ -0,0 +1,24 @@
+package tgmd
+
+import "testing"
+
+func TestFormattingHelpers(t *testing.T) {
+	tests := []struct {
+		name string
+		got  string
+		want string
+	}{
+		{name: "bold", got: WithBold("text"), want: "*text*"},
+		{name: "italic", got: WithItalic("text"), want: "_text_"},
+		{name: "inline code", got: WithInlineCode("text"), want: "`text`"},
+		{name: "link", got: WithLink("Laniakea", "https://example.test"), want: "[Laniakea](https://example.test)"},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			if tc.got != tc.want {
+				t.Fatalf("unexpected formatted text: got %q want %q", tc.got, tc.want)
+			}
+		})
+	}
+}