Function _throws

docs/tests/v2/es6/js/sanddance.js:8699–8735

(shouldThrow, block, expected, message)

}

function _throws(shouldThrow, block, expected, message) {
  var actual;

  if (typeof block !== 'function') {
    throw new TypeError('"block" argument must be a function');
  }

  if (typeof expected === 'string') {
    message = expected;
    expected = null;
  }

  actual = _tryBlock(block);

  message = (expected && expected.name ? ' (' + expected.name + ').' : '.') +
            (message ? ' ' + message : '.');

  if (shouldThrow && !actual) {
    fail(actual, expected, 'Missing expected exception' + message);
  }

  var userProvidedMessage = typeof message === 'string';
  var isUnwantedException = !shouldThrow && util.isError(actual);
  var isUnexpectedException = !shouldThrow && actual && !expected;

  if ((isUnwantedException &&
      userProvidedMessage &&
      expectedException(actual, expected)) ||
      isUnexpectedException) {
    fail(actual, expected, 'Got unwanted exception' + message);
  }

  if ((shouldThrow && actual && expected &&
      !expectedException(actual, expected)) || (!shouldThrow && actual)) {
    throw actual;
  }
}

// 11. Expected to throw an error:
// assert.throws(block, Error_opt, message_opt);