test(line): cover grapheme-safe template fields

vincentkoc · vincentkoc · commit fc4f6dd063fb · 2026-06-28T10:36:49.000-07:00
diff --git a/extensions/line/src/message-cards.test.ts b/extensions/line/src/message-cards.test.ts
@@ -20,13 +20,26 @@ import {
   messageAction,
 } from "./template-messages.js";
 
+const loneHighSurrogate = /[\uD800-\uDBFF](?![\uDC00-\uDFFF])/;
+
 describe("createConfirmTemplate", () => {
   it("truncates text to 240 characters", () => {
     const longText = "x".repeat(300);
     const template = createConfirmTemplate(longText, messageAction("Yes"), messageAction("No"));
 
     expect((template.template as { text: string }).text.length).toBe(240);
   });
+
+  it("drops a surrogate-pair emoji from fallback altText instead of splitting it", () => {
+    const template = createConfirmTemplate(
+      `${"x".repeat(399)}😀`,
+      messageAction("Yes"),
+      messageAction("No"),
+    );
+
+    expect(template.altText).toBe("x".repeat(399));
+    expect(loneHighSurrogate.test(template.altText)).toBe(false);
+  });
 });
 
 describe("createButtonTemplate", () => {
@@ -51,7 +64,16 @@ describe("createButtonTemplate", () => {
     const title = (template.template as { title: string }).title;
 
     expect(title).toBe("x".repeat(39));
-    expect(/[\uD800-\uDBFF](?![\uDC00-\uDFFF])/.test(title)).toBe(false);
+    expect(loneHighSurrogate.test(title)).toBe(false);
+  });
+
+  it("drops a surrogate-pair emoji from explicit altText instead of splitting it", () => {
+    const template = createButtonTemplate("Title", "Text", [messageAction("OK")], {
+      altText: `${"x".repeat(399)}😀`,
+    });
+
+    expect(template.altText).toBe("x".repeat(399));
+    expect(loneHighSurrogate.test(template.altText)).toBe(false);
   });
 
   it("truncates text to 60 chars when no thumbnail is provided", () => {
@@ -105,6 +127,17 @@ describe("createCarouselColumn", () => {
     expect(column.text.length).toBe(60);
   });
 
+  it("drops a surrogate-pair emoji from the title instead of splitting it", () => {
+    const column = createCarouselColumn({
+      title: `${"x".repeat(39)}😀`,
+      text: "Text",
+      actions: [messageAction("OK")],
+    });
+
+    expect(column.title).toBe("x".repeat(39));
+    expect(loneHighSurrogate.test(column.title ?? "")).toBe(false);
+  });
+
   it("does not split an emoji grapheme at the 60-code-unit boundary", () => {
     const text = `${"x".repeat(59)}👨‍👩‍👧‍👦after`;
     const column = createCarouselColumn({
@@ -172,6 +205,16 @@ describe("carousel column limits", () => {
     const template = createTemplate();
     expect((template.template as { columns: unknown[] }).columns.length).toBe(10);
   });
+
+  it("drops a surrogate-pair emoji from image-carousel altText instead of splitting it", () => {
+    const template = createImageCarousel(
+      [createImageCarouselColumn("https://example.com/0.jpg", messageAction("View"))],
+      `${"x".repeat(399)}😀`,
+    );
+
+    expect(template.altText).toBe("x".repeat(399));
+    expect(loneHighSurrogate.test(template.altText)).toBe(false);
+  });
 });
 
 describe("createProductCarousel", () => {
diff --git a/extensions/line/src/template-messages.ts b/extensions/line/src/template-messages.ts
@@ -65,7 +65,10 @@ function truncateTemplateText(text: string, limit: number): string {
   return result;
 }
 
-function truncateOptionalTemplateText(value: string | undefined, limit: number): string | undefined {
+function truncateOptionalTemplateText(
+  value: string | undefined,
+  limit: number,
+): string | undefined {
   return value === undefined ? undefined : truncateTemplateText(value, limit);
 }
 

Original file line number	Diff line number	Diff line change
`@@ -65,7 +65,10 @@ function truncateTemplateText(text: string, limit: number): string {`
`65`	`65`	`return result;`
`66`	`66`	`}`
`67`	`67`
`68`		`-function truncateOptionalTemplateText(value: string \| undefined, limit: number): string \| undefined {`
	`68`	`+function truncateOptionalTemplateText(`
	`69`	`+ value: string \| undefined,`
	`70`	`+ limit: number,`
	`71`	`+): string \| undefined {`
`69`	`72`	`return value === undefined ? undefined : truncateTemplateText(value, limit);`
`70`	`73`	`}`
`71`	`74`