### Question:
Preconditions { public static <T> T checkArgument(T reference, boolean expression) { if (!expression) { throw new IllegalArgumentException(); } return reference; } private  Preconditions(); static String checkNotEmpty(String value); static T checkArgument(T reference, boolean expression); static void checkArgument(boolean expression); static void checkArgument(boolean expression, Object errorMessage); static void checkArgument(boolean expression,
                                     String errorMessageTemplate,
                                     Object... errorMessageArgs);  }### Answer:
@Test public void checkArgumentFailure() { assertThrows(IllegalArgumentException.class, () -> checkArgument(0, false)); }
@Test public void checkArgumentSuccess() { assertThat(checkArgument(0, true), is(0)); }