lts/lib/internal/assert/assertion_error.js
'use strict';
const {
Error,
MathMax,
ObjectCreate,
ObjectDefineProperty,
ObjectGetPrototypeOf,
ObjectKeys,
} = primordials;
const { inspect } = require('internal/util/inspect');
const { codes: {
ERR_INVALID_ARG_TYPE
} } = require('internal/errors');
const {
removeColors,
} = require('internal/util');
let blue = '';
let green = '';
let red = '';
let white = '';
const kReadableOperator = {
deepStrictEqual: 'Expected values to be strictly deep-equal:',
strictEqual: 'Expected values to be strictly equal:',
strictEqualObject: 'Expected "actual" to be reference-equal to "expected":',
deepEqual: 'Expected values to be loosely deep-equal:',
notDeepStrictEqual: 'Expected "actual" not to be strictly deep-equal to:',
notStrictEqual: 'Expected "actual" to be strictly unequal to:',
notStrictEqualObject:
'Expected "actual" not to be reference-equal to "expected":',
notDeepEqual: 'Expected "actual" not to be loosely deep-equal to:',
notIdentical: 'Values have same structure but are not reference-equal:',
notDeepEqualUnequal: 'Expected values not to be loosely deep-equal:'
};
// Comparing short primitives should just show === / !== instead of using the
// diff.
const kMaxShortLength = 12;
function copyError(source) {
const keys = ObjectKeys(source);
const target = ObjectCreate(ObjectGetPrototypeOf(source));
for (const key of keys) {
target[key] = source[key];
}
ObjectDefineProperty(target, 'message', { value: source.message });
return target;
}
function inspectValue(val) {
// The util.inspect default values could be changed. This makes sure the
// error messages contain the necessary information nevertheless.
return inspect(
val,
{
compact: false,
customInspect: false,
depth: 1000,
maxArrayLength: Infinity,
// Assert compares only enumerable properties (with a few exceptions).
showHidden: false,
// Assert does not detect proxies currently.
showProxy: false,
sorted: true,
// Inspect getters as we also check them when comparing entries.
getters: true,
}
);
}
function createErrDiff(actual, expected, operator) {
let other = '';
let res = '';
let end = '';
let skipped = false;
const actualInspected = inspectValue(actual);
const actualLines = actualInspected.split('\n');
const expectedLines = inspectValue(expected).split('\n');
let i = 0;
let indicator = '';
// In case both values are objects or functions explicitly mark them as not
// reference equal for the `strictEqual` operator.
if (operator === 'strictEqual' &&
((typeof actual === 'object' && actual !== null &&
typeof expected === 'object' && expected !== null) ||
(typeof actual === 'function' && typeof expected === 'function'))) {
operator = 'strictEqualObject';
}
// If "actual" and "expected" fit on a single line and they are not strictly
// equal, check further special handling.
if (actualLines.length === 1 && expectedLines.length === 1 &&
actualLines[0] !== expectedLines[0]) {
// Check for the visible length using the `removeColors()` function, if
// appropriate.
const c = inspect.defaultOptions.colors;
const actualRaw = c ? removeColors(actualLines[0]) : actualLines[0];
const expectedRaw = c ? removeColors(expectedLines[0]) : expectedLines[0];
const inputLength = actualRaw.length + expectedRaw.length;
// If the character length of "actual" and "expected" together is less than
// kMaxShortLength and if neither is an object and at least one of them is
// not `zero`, use the strict equal comparison to visualize the output.
if (inputLength <= kMaxShortLength) {
if ((typeof actual !== 'object' || actual === null) &&
(typeof expected !== 'object' || expected === null) &&
(actual !== 0 || expected !== 0)) { // -0 === +0
return `${kReadableOperator[operator]}\n\n` +
`${actualLines[0]} !== ${expectedLines[0]}\n`;
}
} else if (operator !== 'strictEqualObject') {
// If the stderr is a tty and the input length is lower than the current
// columns per line, add a mismatch indicator below the output. If it is
// not a tty, use a default value of 80 characters.
const maxLength = process.stderr.isTTY ? process.stderr.columns : 80;
if (inputLength < maxLength) {
while (actualRaw[i] === expectedRaw[i]) {
i++;
}
// Ignore the first characters.
if (i > 2) {
// Add position indicator for the first mismatch in case it is a
// single line and the input length is less than the column length.
indicator = `\n ${' '.repeat(i)}^`;
i = 0;
}
}
}
}
// Remove all ending lines that match (this optimizes the output for
// readability by reducing the number of total changed lines).
let a = actualLines[actualLines.length - 1];
let b = expectedLines[expectedLines.length - 1];
while (a === b) {
if (i++ < 3) {
end = `\n ${a}${end}`;
} else {
other = a;
}
actualLines.pop();
expectedLines.pop();
if (actualLines.length === 0 || expectedLines.length === 0)
break;
a = actualLines[actualLines.length - 1];
b = expectedLines[expectedLines.length - 1];
}
const maxLines = MathMax(actualLines.length, expectedLines.length);
// Strict equal with identical objects that are not identical by reference.
// E.g., assert.deepStrictEqual({ a: Symbol() }, { a: Symbol() })
if (maxLines === 0) {
// We have to get the result again. The lines were all removed before.
const actualLines = actualInspected.split('\n');
// Only remove lines in case it makes sense to collapse those.
// TODO: Accept env to always show the full error.
if (actualLines.length > 50) {
actualLines[46] = `${blue}...${white}`;
while (actualLines.length > 47) {
actualLines.pop();
}
}
return `${kReadableOperator.notIdentical}\n\n${actualLines.join('\n')}\n`;
}
// There were at least five identical lines at the end. Mark a couple of
// skipped.
if (i >= 5) {
end = `\n${blue}...${white}${end}`;
skipped = true;
}
if (other !== '') {
end = `\n ${other}${end}`;
other = '';
}
let printedLines = 0;
let identical = 0;
const msg = kReadableOperator[operator] +
`\n${green}+ actual${white} ${red}- expected${white}`;
const skippedMsg = ` ${blue}...${white} Lines skipped`;
let lines = actualLines;
let plusMinus = `${green}+${white}`;
let maxLength = expectedLines.length;
if (actualLines.length < maxLines) {
lines = expectedLines;
plusMinus = `${red}-${white}`;
maxLength = actualLines.length;
}
for (i = 0; i < maxLines; i++) {
if (maxLength < i + 1) {
// If more than two former lines are identical, print them. Collapse them
// in case more than five lines were identical.
if (identical > 2) {
if (identical > 3) {
if (identical > 4) {
if (identical === 5) {
res += `\n ${lines[i - 3]}`;
printedLines++;
} else {
res += `\n${blue}...${white}`;
skipped = true;
}
}
res += `\n ${lines[i - 2]}`;
printedLines++;
}
res += `\n ${lines[i - 1]}`;
printedLines++;
}
// No identical lines before.
identical = 0;
// Add the expected line to the cache.
if (lines === actualLines) {
res += `\n${plusMinus} ${lines[i]}`;
} else {
other += `\n${plusMinus} ${lines[i]}`;
}
printedLines++;
// Only extra actual lines exist
// Lines diverge
} else {
const expectedLine = expectedLines[i];
let actualLine = actualLines[i];
// If the lines diverge, specifically check for lines that only diverge by
// a trailing comma. In that case it is actually identical and we should
// mark it as such.
let divergingLines = actualLine !== expectedLine &&
(!actualLine.endsWith(',') ||
actualLine.slice(0, -1) !== expectedLine);
// If the expected line has a trailing comma but is otherwise identical,
// add a comma at the end of the actual line. Otherwise the output could
// look weird as in:
//
// [
// 1 // No comma at the end!
// + 2
// ]
//
if (divergingLines &&
expectedLine.endsWith(',') &&
expectedLine.slice(0, -1) === actualLine) {
divergingLines = false;
actualLine += ',';
}
if (divergingLines) {
// If more than two former lines are identical, print them. Collapse
// them in case more than five lines were identical.
if (identical > 2) {
if (identical > 3) {
if (identical > 4) {
if (identical === 5) {
res += `\n ${actualLines[i - 3]}`;
printedLines++;
} else {
res += `\n${blue}...${white}`;
skipped = true;
}
}
res += `\n ${actualLines[i - 2]}`;
printedLines++;
}
res += `\n ${actualLines[i - 1]}`;
printedLines++;
}
// No identical lines before.
identical = 0;
// Add the actual line to the result and cache the expected diverging
// line so consecutive diverging lines show up as +++--- and not +-+-+-.
res += `\n${green}+${white} ${actualLine}`;
other += `\n${red}-${white} ${expectedLine}`;
printedLines += 2;
// Lines are identical
} else {
// Add all cached information to the result before adding other things
// and reset the cache.
res += other;
other = '';
identical++;
// The very first identical line since the last diverging line is be
// added to the result.
if (identical <= 2) {
res += `\n ${actualLine}`;
printedLines++;
}
}
}
// Inspected object to big (Show ~50 rows max)
if (printedLines > 50 && i < maxLines - 2) {
return `${msg}${skippedMsg}\n${res}\n${blue}...${white}${other}\n` +
`${blue}...${white}`;
}
}
return `${msg}${skipped ? skippedMsg : ''}\n${res}${other}${end}${indicator}`;
}
class AssertionError extends Error {
constructor(options) {
if (typeof options !== 'object' || options === null) {
throw new ERR_INVALID_ARG_TYPE('options', 'Object', options);
}
const {
message,
operator,
stackStartFn,
// Compatibility with older versions.
stackStartFunction
} = options;
let {
actual,
expected
} = options;
const limit = Error.stackTraceLimit;
Error.stackTraceLimit = 0;
if (message != null) {
super(String(message));
} else {
if (process.stderr.isTTY) {
// Reset on each call to make sure we handle dynamically set environment
// variables correct.
if (process.stderr.hasColors()) {
blue = '\u001b[34m';
green = '\u001b[32m';
white = '\u001b[39m';
red = '\u001b[31m';
} else {
blue = '';
green = '';
white = '';
red = '';
}
}
// Prevent the error stack from being visible by duplicating the error
// in a very close way to the original in case both sides are actually
// instances of Error.
if (typeof actual === 'object' && actual !== null &&
typeof expected === 'object' && expected !== null &&
'stack' in actual && actual instanceof Error &&
'stack' in expected && expected instanceof Error) {
actual = copyError(actual);
expected = copyError(expected);
}
if (operator === 'deepStrictEqual' || operator === 'strictEqual') {
super(createErrDiff(actual, expected, operator));
} else if (operator === 'notDeepStrictEqual' ||
operator === 'notStrictEqual') {
// In case the objects are equal but the operator requires unequal, show
// the first object and say A equals B
let base = kReadableOperator[operator];
const res = inspectValue(actual).split('\n');
// In case "actual" is an object or a function, it should not be
// reference equal.
if (operator === 'notStrictEqual' &&
((typeof actual === 'object' && actual !== null) ||
typeof actual === 'function')) {
base = kReadableOperator.notStrictEqualObject;
}
// Only remove lines in case it makes sense to collapse those.
// TODO: Accept env to always show the full error.
if (res.length > 50) {
res[46] = `${blue}...${white}`;
while (res.length > 47) {
res.pop();
}
}
// Only print a single input.
if (res.length === 1) {
super(`${base}${res[0].length > 5 ? '\n\n' : ' '}${res[0]}`);
} else {
super(`${base}\n\n${res.join('\n')}\n`);
}
} else {
let res = inspectValue(actual);
let other = inspectValue(expected);
const knownOperator = kReadableOperator[operator];
if (operator === 'notDeepEqual' && res === other) {
res = `${knownOperator}\n\n${res}`;
if (res.length > 1024) {
res = `${res.slice(0, 1021)}...`;
}
super(res);
} else {
if (res.length > 512) {
res = `${res.slice(0, 509)}...`;
}
if (other.length > 512) {
other = `${other.slice(0, 509)}...`;
}
if (operator === 'deepEqual') {
res = `${knownOperator}\n\n${res}\n\nshould loosely deep-equal\n\n`;
} else {
const newOp = kReadableOperator[`${operator}Unequal`];
if (newOp) {
res = `${newOp}\n\n${res}\n\nshould not loosely deep-equal\n\n`;
} else {
other = ` ${operator} ${other}`;
}
}
super(`${res}${other}`);
}
}
}
Error.stackTraceLimit = limit;
this.generatedMessage = !message;
ObjectDefineProperty(this, 'name', {
value: 'AssertionError [ERR_ASSERTION]',
enumerable: false,
writable: true,
configurable: true
});
this.code = 'ERR_ASSERTION';
this.actual = actual;
this.expected = expected;
this.operator = operator;
// eslint-disable-next-line no-restricted-syntax
Error.captureStackTrace(this, stackStartFn || stackStartFunction);
// Create error message including the error code in the name.
this.stack;
// Reset the name.
this.name = 'AssertionError';
}
toString() {
return `${this.name} [${this.code}]: ${this.message}`;
}
[inspect.custom](recurseTimes, ctx) {
// Long strings should not be fully inspected.
const tmpActual = this.actual;
const tmpExpected = this.expected;
for (const name of ['actual', 'expected']) {
if (typeof this[name] === 'string') {
const lines = this[name].split('\n');
if (lines.length > 10) {
lines.length = 10;
this[name] = `${lines.join('\n')}\n...`;
} else if (this[name].length > 512) {
this[name] = `${this[name].slice(512)}...`;
}
}
}
// This limits the `actual` and `expected` property default inspection to
// the minimum depth. Otherwise those values would be too verbose compared
// to the actual error message which contains a combined view of these two
// input values.
const result = inspect(this, {
...ctx,
customInspect: false,
depth: 0
});
// Reset the properties after inspection.
this.actual = tmpActual;
this.expected = tmpExpected;
return result;
}
}
module.exports = AssertionError;