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lib: add word-level diff for string comparisons #60527

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70 changes: 70 additions & 0 deletions lib/internal/assert/assertion_error.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,11 +6,14 @@ const {
ArrayPrototypeSlice,
Error,
ErrorCaptureStackTrace,
MathMax,
ObjectAssign,
ObjectDefineProperty,
ObjectGetPrototypeOf,
ObjectPrototypeHasOwnProperty,
RegExpPrototypeSymbolSplit,
String,
StringPrototypeIncludes,
StringPrototypeRepeat,
StringPrototypeSlice,
StringPrototypeSplit,
Expand Down Expand Up @@ -41,6 +44,7 @@ const kReadableOperator = {

const kMaxShortStringLength = 12;
const kMaxLongStringLength = 512;
const kMaxDiffDensityForWordDiff = 0.5;

const kMethodsWithCustomMessageDiff = ['deepStrictEqual', 'strictEqual', 'partialDeepStrictEqual'];

Expand Down Expand Up @@ -104,6 +108,68 @@ function checkOperator(actual, expected, operator) {
return operator;
}

function splitByWordBoundaries(str) {
return RegExpPrototypeSymbolSplit(/(\s+|_+|-+)/, str);
}

function calculateDiffDensity(actual, expected) {
const diff = myersDiff(StringPrototypeSplit(actual, ''), StringPrototypeSplit(expected, ''));
let changedChars = 0;

for (let i = 0; i < diff.length; i++) {
const operation = diff[i][0];
if (operation !== 0) {
changedChars++;
}
}

const totalChars = MathMax(actual.length, expected.length);
return totalChars === 0 ? 0 : changedChars / totalChars;
}

function checksUseOfWordDiff(actual, expected) {
const hasWordBoundaries = StringPrototypeIncludes(actual, ' ') ||
StringPrototypeIncludes(actual, '_') ||
StringPrototypeIncludes(actual, '-') ||
StringPrototypeIncludes(expected, ' ') ||
StringPrototypeIncludes(expected, '_') ||
StringPrototypeIncludes(expected, '-');

if (!hasWordBoundaries) {
return false;
}

const diffDensity = calculateDiffDensity(actual, expected);

return diffDensity <= kMaxDiffDensityForWordDiff;
}

function getWordDiff(actual, expected) {
const header = `${colors.green}actual${colors.white} ${colors.red}expected${colors.white}`;
const skipped = false;

const actualWords = splitByWordBoundaries(actual);
const expectedWords = splitByWordBoundaries(expected);

const diff = myersDiff(actualWords, expectedWords);
let message = '\n';

for (let diffIdx = diff.length - 1; diffIdx >= 0; diffIdx--) {
const { 0: operation, 1: value } = diff[diffIdx];
let color = colors.white;

if (operation === 1) {
color = colors.green;
} else if (operation === -1) {
color = colors.red;
}

message += `${color}${value}${colors.white}`;
}

return { message, header, skipped };
}

function getColoredMyersDiff(actual, expected) {
const header = `${colors.green}actual${colors.white} ${colors.red}expected${colors.white}`;
const skipped = false;
Expand Down Expand Up @@ -164,6 +230,10 @@ function getSimpleDiff(originalActual, actual, originalExpected, expected) {
const isStringComparison = typeof originalActual === 'string' && typeof originalExpected === 'string';
// colored myers diff
if (isStringComparison && colors.hasColors) {
// We don't want include quotes for word diff checks
if (checksUseOfWordDiff(originalActual, originalExpected)) {
return getWordDiff(originalActual, originalExpected);
}
return getColoredMyersDiff(actual, expected);
}

Expand Down
150 changes: 150 additions & 0 deletions test/parallel/test-assert.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1777,5 +1777,155 @@ test('Functions as error message', () => {
);
});

test('Word-level diff for strings with word boundaries', () => {
process.env.FORCE_COLOR = '1';
delete process.env.NODE_DISABLE_COLORS;
delete process.env.NO_COLOR;

assert.throws(
() => assert.strictEqual('the quick brown fox', 'the quick black fox'),
{
code: 'ERR_ASSERTION',
name: 'AssertionError',
generatedMessage: true,
message: 'Expected values to be strictly equal:\n' +
'\u001b[32mactual\u001b[39m \u001b[31mexpected\u001b[39m\n' +
'\n' +
'\u001b[39mthe\u001b[39m\u001b[39m \u001b[39m\u001b[39mquick\u001b[39m' +
'\u001b[39m \u001b[39m\u001b[32mbrown\u001b[39m\u001b[31mblack\u001b[39m' +
'\u001b[39m \u001b[39m\u001b[39mfox\u001b[39m\n'
}
);

assert.throws(
() => assert.strictEqual('hello_world_test', 'hello_there_test'),
{
code: 'ERR_ASSERTION',
name: 'AssertionError',
generatedMessage: true,
message: 'Expected values to be strictly equal:\n' +
'\u001b[32mactual\u001b[39m \u001b[31mexpected\u001b[39m\n' +
'\n' +
'\u001b[39mhello\u001b[39m\u001b[39m_\u001b[39m' +
'\u001b[32mworld\u001b[39m\u001b[31mthere\u001b[39m' +
'\u001b[39m_\u001b[39m\u001b[39mtest\u001b[39m\n'
}
);

assert.throws(
() => assert.strictEqual('hello-world-test', 'hello-there-test'),
{
code: 'ERR_ASSERTION',
name: 'AssertionError',
generatedMessage: true,
message: 'Expected values to be strictly equal:\n' +
'\u001b[32mactual\u001b[39m \u001b[31mexpected\u001b[39m\n' +
'\n' +
'\u001b[39mhello\u001b[39m\u001b[39m-\u001b[39m' +
'\u001b[32mworld\u001b[39m\u001b[31mthere\u001b[39m' +
'\u001b[39m-\u001b[39m\u001b[39mtest\u001b[39m\n'
}
);

assert.throws(
() => assert.strictEqual('abcdefghij', 'abcdxfghij'),
{
code: 'ERR_ASSERTION',
name: 'AssertionError',
generatedMessage: true,
message: 'Expected values to be strictly equal:\n' +
'\u001b[32mactual\u001b[39m \u001b[31mexpected\u001b[39m\n' +
'\n' +
'\u001b[39m\'\u001b[39m\u001b[39ma\u001b[39m\u001b[39mb\u001b[39m' +
'\u001b[39mc\u001b[39m\u001b[39md\u001b[39m\u001b[32me\u001b[39m' +
'\u001b[31mx\u001b[39m\u001b[39mf\u001b[39m\u001b[39mg\u001b[39m' +
'\u001b[39mh\u001b[39m\u001b[39mi\u001b[39m\u001b[39mj\u001b[39m\u001b[39m\'\u001b[39m\n'
}
);

assert.throws(
() => assert.strictEqual('hello_world-test case', 'hello_there-test case'),
{
code: 'ERR_ASSERTION',
name: 'AssertionError',
generatedMessage: true,
message: 'Expected values to be strictly equal:\n' +
'\u001b[32mactual\u001b[39m \u001b[31mexpected\u001b[39m\n' +
'\n' +
'\u001b[39mhello\u001b[39m\u001b[39m_\u001b[39m' +
'\u001b[32mworld\u001b[39m\u001b[31mthere\u001b[39m' +
'\u001b[39m-\u001b[39m\u001b[39mtest\u001b[39m' +
'\u001b[39m \u001b[39m\u001b[39mcase\u001b[39m\n'
}
);

assert.throws(
() => assert.strictEqual('version 1 2 3', 'version 1 2 4'),
{
code: 'ERR_ASSERTION',
name: 'AssertionError',
generatedMessage: true,
message: 'Expected values to be strictly equal:\n' +
'\u001b[32mactual\u001b[39m \u001b[31mexpected\u001b[39m\n' +
'\n' +
'\u001b[39mversion\u001b[39m\u001b[39m \u001b[39m' +
'\u001b[39m1\u001b[39m\u001b[39m \u001b[39m' +
'\u001b[39m2\u001b[39m\u001b[39m \u001b[39m' +
'\u001b[32m3\u001b[39m\u001b[31m4\u001b[39m\n'
}
);

assert.throws(
() => assert.strictEqual('hello world', 'hello world'),
{
code: 'ERR_ASSERTION',
name: 'AssertionError',
generatedMessage: true,
message: 'Expected values to be strictly equal:\n' +
'\u001b[32mactual\u001b[39m \u001b[31mexpected\u001b[39m\n' +
'\n' +
'\u001b[39mhello\u001b[39m' +
'\u001b[32m \u001b[39m\u001b[31m \u001b[39m' +
'\u001b[39mworld\u001b[39m\n'
}
);

assert.throws(
() => assert.strictEqual('test@example.com foo', 'test@example.com bar'),
{
code: 'ERR_ASSERTION',
name: 'AssertionError',
generatedMessage: true,
message: 'Expected values to be strictly equal:\n' +
'\u001b[32mactual\u001b[39m \u001b[31mexpected\u001b[39m\n' +
'\n' +
'\u001b[39mtest@example.com\u001b[39m\u001b[39m \u001b[39m' +
'\u001b[32mfoo\u001b[39m\u001b[31mbar\u001b[39m\n'
}
);

// Fall back to character diff because of word density
assert.throws(
() => assert.strictEqual('hello', 'hallo'),
{
code: 'ERR_ASSERTION',
name: 'AssertionError',
generatedMessage: true,
message: "Expected values to be strictly equal:\n\n'hello' !== 'hallo'\n"
}
);

assert.throws(
() => assert.strictEqual('', 'hello world'),
{
code: 'ERR_ASSERTION',
name: 'AssertionError',
generatedMessage: true,
message: "Expected values to be strictly equal:\n\n'' !== 'hello world'\n"
}
);

});

/* eslint-enable no-restricted-syntax */
/* eslint-enable no-restricted-properties */