### Question:
Arguments { public static String checkOneCharString(final String string, final String name) throws IllegalArgumentException { if (string == null || string.length() != 1) { throw new IllegalArgumentException("Expecting a one char string for " + name); } return string; } private  Arguments(); static String checkNonEmpty(final String string, final String name); static String checkOneCharString(final String string, final String name); static String checkDuration(final String string, final String name); static String checkDurationNotRequired(final String string, final String name); static void checkPositiveNumber(final Number number, final String name); static void checkNotNegativeNumber(final Number number, final String name); static void checkNotNull(final Object obj, final String name); static void checkPrecision(@Nullable final ChronoUnit precision);  }### Answer:
@Test void checkOneCharString() { Arguments.checkOneCharString("#", "valid"); }
@Test void checkOneCharStringEmpty() { Assertions.assertThatThrownBy(() -> Arguments.checkOneCharString("", "property")) .isInstanceOf(IllegalArgumentException.class) .hasMessage("Expecting a one char string for property"); }
@Test void checkOneCharStringNull() { Assertions.assertThatThrownBy(() -> Arguments.checkOneCharString(null, "property")) .isInstanceOf(IllegalArgumentException.class) .hasMessage("Expecting a one char string for property"); }
@Test void checkOneCharStringLarge() { Assertions.assertThatThrownBy(() -> Arguments.checkOneCharString("##", "property")) .isInstanceOf(IllegalArgumentException.class) .hasMessage("Expecting a one char string for property"); }