@Test
    public final void createExtentionWithoutCredentials() {
        S3ProxyRule extension = S3ProxyRule
                .builder()
                .build();
        assertThat(extension.getAccessKey()).isNull();
        assertThat(extension.getSecretKey()).isNull();
        assertThat(extension.getUri()).isNull();
    }
This is an example of how one would use the S3Proxy JUnit rule in a unit
test as opposed to a proper test of the S3ProxyRule class.
src/test/java/org/gaul/s3proxy/junit/S3ProxyRuleTest.java