Personality, like human being is constantly changing and developing. The development of a person's personality continues throughout a person's lifetime as it is very unlikely that a person will remain the same after a lifetime full of ups and downs as what Erikson's theory emphasizes that social experiences for the whole lifespan will affect our personality development. I also believe that from my short life experiences and observations. I believe, as human, if we permit ourselves, we will learn from all life experiences that will then make up our personality. But personality development is a never ending process, it continues until the day we die.
The purpose of taking the personality test is to get a raw idea of how our behaviours and everyday actions tell us about our personality. Even though we or the ones closed to us can be trusted judges on our personality, a personality test may unfold more about our personality that we or our loved ones may have overlook. It is a good idea of taking the personality test because this test was well prepared by many expert researchers who have dedicated their lives to study about the human personality and the factors that caused each and every one of us to be unique and different from one another. One of the example of such test is in the website http://test.personality-project.org/. Thus, if we answer the questions truthfully, the result would be the closest idea to our personality.
The knowledge of one's own personality can help one understanding of how he represents himself to the society, how others perceived him and how he can actually manipulate this knowledge for his benefit in the sense that he can change himself to be what he wants himself to be and creates his own ideal self-brand. This is what the humanistic theorists believe, that humans have freedom to chart our own courses of life and have the innate drive within ourselves for personal growth. I personally agree with their
References: Papalia, D.E., Olds,S.W.,Feldman,R.D. (2009). Human Development.(11th Edition). McGraw-Hill : New York Madam Aina Razlin 's slides.