test(config): prove UTF-16 allowed-value hint boundary

steipete · steipete · commit 4c05d91e247f · 2026-07-09T08:49:06.000+01:00
diff --git a/src/config/allowed-values.test.ts b/src/config/allowed-values.test.ts
@@ -23,6 +23,17 @@ describe("summarizeAllowedValues", () => {
     });
   });
 
+  it("counts the omitted UTF-16 units after preserving a surrogate pair", () => {
+    const prefix = "a".repeat(159);
+    const value = `${prefix}😀tail`;
+
+    expect(summarizeAllowedValues([value])).toStrictEqual({
+      formatted: `"${prefix}... (+6 chars)"`,
+      hiddenCount: 0,
+      values: [value],
+    });
+  });
+
   it("returns empty label for undefined allowed value", () => {
     const summary = summarizeAllowedValues([undefined]);
     expect(summary).toStrictEqual({
diff --git a/src/config/allowed-values.ts b/src/config/allowed-values.ts
@@ -15,7 +15,8 @@ function truncateHintText(text: string, limit: number): string {
   if (text.length <= limit) {
     return text;
   }
-  return `${truncateUtf16Safe(text, limit)}... (+${text.length - limit} chars)`;
+  const truncated = truncateUtf16Safe(text, limit);
+  return `${truncated}... (+${text.length - truncated.length} chars)`;
 }
 
 function safeStringify(value: unknown): string {

Original file line number	Diff line number	Diff line change
`@@ -15,7 +15,8 @@ function truncateHintText(text: string, limit: number): string {`
`15`	`15`	`if (text.length <= limit) {`
`16`	`16`	`return text;`
`17`	`17`	`}`
`18`		- return `${truncateUtf16Safe(text, limit)}... (+${text.length - limit} chars)`;
	`18`	`+ const truncated = truncateUtf16Safe(text, limit);`
	`19`	+ return `${truncated}... (+${text.length - truncated.length} chars)`;
`19`	`20`	`}`
`20`	`21`
`21`	`22`	`function safeStringify(value: unknown): string {`