@Test
public void testResolveExceptionCode_resolver_is_undefine() {

    // do setup.
    testTarget = new DefaultExceptionLevelResolver();
    Exception exception = new SystemException("i.w.e", "error.");
    // do test.
    ExceptionLevel actualExceptionLevel = testTarget.resolveExceptionLevel(
            exception);
    // do assert.
    ExceptionLevel expectedExceptionLevel = ExceptionLevel.ERROR;
    assertThat(actualExceptionLevel, is(expectedExceptionLevel));
}