'use strict';

/**
 * Tests for splitLines in src/lines.js.
 *
 * Run with:  node --test
 * (or)       node --test test/lines.test.js
 *
 * The helper must count lines the way editors and `wc -l` do: a trailing
 * newline terminates the final line rather than starting an extra empty one.
 */

import test from 'node:test';
import assert from 'node:assert/strict';

import { splitLines } from '../src/lines.js';

test('splitLines: empty file has no lines', () => {
    assert.deepEqual(splitLines(''), []);
});

test('splitLines: no trailing newline is unchanged', () => {
    assert.deepEqual(splitLines('a\nb\nc'), ['a', 'b', 'c']);
});

test('splitLines: trailing newline does not add a phantom line', () => {
    // The reported bug: this used to yield 4 elements (['a','b','c','']).
    assert.deepEqual(splitLines('a\nb\nc\n'), ['a', 'b', 'c']);
    assert.equal(splitLines('a\nb\nc\n').length, 3);
});

test('splitLines: terminated and non-terminated agree on line count', () => {
    assert.equal(splitLines('a\nb\nc\n').length, splitLines('a\nb\nc').length);
});

test('splitLines: a real trailing blank line is preserved', () => {
    assert.deepEqual(splitLines('a\n\n'), ['a', '']);
    assert.equal(splitLines('a\n\n').length, 2);
});

test('splitLines: a lone newline is one empty line', () => {
    assert.deepEqual(splitLines('\n'), ['']);
    assert.equal(splitLines('\n').length, 1);
});

test('splitLines: multiple trailing newlines keep the real blank lines', () => {
    assert.deepEqual(splitLines('a\n\n\n'), ['a', '', '']);
    assert.equal(splitLines('a\n\n\n').length, 3);
});