src/main/java/org/fest/assertions/StringAssert.java
public @NotNull StringAssert doesNotMatch(String regex) {
    isNotNull();
    if (!actual.matches(regex)) {
      return this;
    }
    failIfCustomMessageIsSet();
    throw failure(format("<%s> should not match the regular expression:<%s>", actual, regex));
  }
public @NotNull StringAssert doesNotMatch(String regex) {
    isNotNull();
    if (!actual.matches(regex)) {
      return this;
    }
    failIfCustomMessageIsSet();
    throw failure(format("<%s> should not match the regular expression:<%s>", actual, regex));
  }
Verifies that the actual {@code String} does not match the given one.

@param regex the given regular expression expected not to be matched by the actual one.
@return this assertion object.
@throws AssertionError if the actual {@code String} is {@code null}.
@throws AssertionError if the actual {@code String} matches the given regular expression.