function getErrMessage(call) {
const filename = call.getFileName();
const line = call.getLineNumber() - 1;
const column = call.getColumnNumber() - 1;
const identifier = `${filename}${line}${column}`;
if (errorCache.has(identifier)) {
return errorCache.get(identifier);
}
// Skip Node.js modules!
if (filename.endsWith('.js') && NativeModule.exists(filename.slice(0, -3))) {
errorCache.set(identifier, undefined);
return;
}
let fd, message;
try {
fd = openSync(filename, 'r', 0o666);
const buffers = getBuffer(fd, line);
const code = Buffer.concat(buffers).toString('utf8');
// Lazy load acorn.
const { parseExpressionAt } = require('internal/deps/acorn/dist/acorn');
const nodes = parseExpressionAt(code, column);
// Node type should be "CallExpression" and some times
// "SequenceExpression".
const node = nodes.type === 'CallExpression' ? nodes : nodes.expressions[0];
const name = node.callee.name;
// Calling `ok` with .apply or .call is uncommon but we use a simple
// safeguard nevertheless.
if (name !== 'apply' && name !== 'call') {
// Only use `assert` and `assert.ok` to reference the "real API" and
// not user defined function names.
const ok = name === 'ok' ? '.ok' : '';
const args = node.arguments;
message = code
.slice(args[0].start, args[args.length - 1].end)
.replace(escapeSequencesRegExp, escapeFn);
if (EOL === '\r\n') {
message = message.replace(/\r\n/g, '\n');
}
message = 'The expression evaluated to a falsy value:' +
`\n\n assert${ok}(${message})\n`;
}
// Make sure to always set the cache! No matter if the message is
// undefined or not
errorCache.set(identifier, message);
return message;
} catch (e) {
// Invalidate cache to prevent trying to read this part again.
errorCache.set(identifier, undefined);
} finally {
if (fd !== undefined)
closeSync(fd);
}
}
// Do not try to check Node.js modules.
{
const e = new EventEmitter();
e.on('hello', assert);
let threw = false;
try {
e.emit('hello', false);
} catch (err) {
const frames = err.stack.split('\n');
const [, filename, line, column] = frames[1].match(/\((.+):(\d+):(\d+)\)/);
// Reset the cache to check again
const size = errorCache.size;
errorCache.delete(`${filename}${line - 1}${column - 1}`);
assert.strictEqual(errorCache.size, size - 1);
const data = `${'\n'.repeat(line - 1)}${' '.repeat(column - 1)}` +
'ok(failed(badly));';
try {
writeFileSync(filename, data);
assert.throws(
() => e.emit('hello', false),
{
message: 'false == true'
}
);
threw = true;
} finally {
unlinkSync(filename);
}