@Contract("false, _, _ -> fail")
  public static void that(boolean condition, String msg, Object... values) {
    if (!condition) throw new InternalSpockError(String.format(msg, values));
  }
Assertions for use within Spock code. Failures indicate internal errors.

@author Peter Niederwieser
spock-core/src/main/java/org/spockframework/util/Assert.java