it.each(["", " \n\n "] as const)("returns empty array for input %j", (text) => {

expect(chunkByNewline(text, 100)).toStrictEqual([]);

});

it("does not split surrogate pairs when hard-splitting an over-long line", () => {

// An emoji-dense line with no break point forces the raw head cut at an odd code-unit offset;

// it must back off to a code-point boundary so no chunk ends in a high (or starts with a low)

// surrogate — the same contract the recursive chunkText path already honors.

const text = "😀".repeat(30);

const chunks = chunkByNewline(text, 11);

expect(chunks.join("")).toBe(text);

expect(chunks.length).toBeGreaterThan(1);

expect(chunks.every((chunk) => !/[\uD800-\uDBFF]$/u.test(chunk))).toBe(true);

expect(chunks.every((chunk) => !/^[\uDC00-\uDFFF]/u.test(chunk))).toBe(true);

});

});

describe("chunkTextWithMode", () => {

continue;

}

const firstLimit = Math.max(1, maxLineLength - prefix.length);

// Back the head cut off to a code-point boundary so an over-long line never splits a surrogate

// pair; the recursive chunkText below is already surrogate-safe, only this first cut was raw.

const rawLimit = Math.max(1, maxLineLength - prefix.length);

const firstLimit = avoidTrailingHighSurrogateBreak(lineValue, 0, rawLimit);

const first = lineValue.slice(0, firstLimit);

chunks.push(prefix + first);

const remaining = lineValue.slice(firstLimit);