feat: Initial clean release of CHM

packages/lib/services/conflict/wordDiff.test.ts

@@ -0,0 +1,101 @@
+import { wordDiff, WordDiffSegment } from './wordDiff';
+
+const highlightedText = (segments: WordDiffSegment[]) => {
+	return segments.filter(s => s.highlighted).map(s => s.text);
+};
+
+const joined = (segments: WordDiffSegment[]) => {
+	return segments.map(s => s.text).join('');
+};
+
+describe('wordDiff', () => {
+
+	test('should return a single unhighlighted segment per side when the texts match', () => {
+		const diff = wordDiff('same text', 'same text');
+		expect(diff.local).toEqual([{ text: 'same text', highlighted: false }]);
+		expect(diff.remote).toEqual([{ text: 'same text', highlighted: false }]);
+	});
+
+	test('should highlight only the words that differ', () => {
+		const diff = wordDiff('the quick brown fox', 'the quick red fox');
+		expect(highlightedText(diff.local)).toEqual(['brown']);
+		expect(highlightedText(diff.remote)).toEqual(['red']);
+	});
+
+	// cSpell:disable
+	test('should highlight the whole word when a single character differs', () => {
+		const diff = wordDiff('these are similar words', 'these are similer words');
+		expect(highlightedText(diff.local)).toEqual(['similar']);
+		expect(highlightedText(diff.remote)).toEqual(['similer']);
+	});
+	// cSpell:enable
+
+	test.each([
+		['word added on remote', 'one two', 'one extra two', [], ['extra ']],
+		['word removed on remote', 'one extra two', 'one two', ['extra '], []],
+		['punctuation change highlights only the mark', 'the end.', 'the end!', ['.'], ['!']],
+		['fully different texts', 'mine', 'theirs', ['mine'], ['theirs']],
+	])('%s', (_label, local, remote, expectedLocal, expectedRemote) => {
+		const diff = wordDiff(local, remote);
+		expect(highlightedText(diff.local)).toEqual(expectedLocal);
+		expect(highlightedText(diff.remote)).toEqual(expectedRemote);
+	});
+
+	test('should keep multiple changes as separate highlights', () => {
+		const diff = wordDiff('alpha two gamma four', 'ALPHA two GAMMA four');
+		expect(highlightedText(diff.local)).toEqual(['alpha', 'gamma']);
+		expect(highlightedText(diff.remote)).toEqual(['ALPHA', 'GAMMA']);
+	});
+
+	test.each([
+		['single word change', 'the quick brown fox', 'the quick red fox'],
+		['multi-line text', 'line one\nline two\nline three', 'line one\nline 2\nline three'],
+		['whitespace change', 'a  b', 'a b'],
+		['one side empty', '', 'new text'],
+		['adjacent changed words', 'one two three', 'ONE TWO three'],
+	])('segments should reconstruct both inputs: %s', (_label, local, remote) => {
+		const diff = wordDiff(local, remote);
+		expect(joined(diff.local)).toBe(local);
+		expect(joined(diff.remote)).toBe(remote);
+	});
+
+	test('should return no segments for an empty side', () => {
+		const diff = wordDiff('', 'text');
+		expect(diff.local).toEqual([]);
+		expect(highlightedText(diff.remote)).toEqual(['text']);
+	});
+
+	// jsdiff only treats Latin text as words. These tests make sure non-Latin
+	// words are still highlighted correctly.
+	// cSpell:disable
+	test.each([
+		['cyrillic', 'привет мир', 'привет всем', ['мир'], ['всем']],
+		['greek', 'αλφα βητα', 'αλφα γαμμα', ['βητα'], ['γαμμα']],
+		['arabic', 'مرحبا بالعالم', 'مرحبا بالجميع', ['بالعالم'], ['بالجميع']],
+		['hebrew', 'שלום עולם', 'שלום חברים', ['עולם'], ['חברים']],
+		['accented latin', 'café au lait', 'caffé au lait', ['café'], ['caffé']],
+		['mixed-script word', 'see appleмир here', 'see apple here', ['appleмир'], ['apple']],
+	])('should highlight whole words in non-Latin scripts: %s', (_label, local, remote, expectedLocal, expectedRemote) => {
+		const diff = wordDiff(local, remote);
+		expect(highlightedText(diff.local)).toEqual(expectedLocal);
+		expect(highlightedText(diff.remote)).toEqual(expectedRemote);
+	});
+
+	test('should highlight per character in unspaced CJK text', () => {
+		const diff = wordDiff('これはペンです', 'これは本です');
+		expect(highlightedText(diff.local)).toEqual(['ペン']);
+		expect(highlightedText(diff.remote)).toEqual(['本']);
+	});
+	// cSpell:enable
+
+	test('should keep unchanged whitespace between changed words unhighlighted', () => {
+		const diff = wordDiff('one two three', 'ONE TWO three');
+		expect(diff.local).toEqual([
+			{ text: 'one', highlighted: true },
+			{ text: ' ', highlighted: false },
+			{ text: 'two', highlighted: true },
+			{ text: ' three', highlighted: false },
+		]);
+	});
+
+});