@Override
    public String getAvailabilityZone() {
        return awsMetadataApi.availabilityZoneEc2();
    }
@Test
    public void getAvailabilityZone() {
        // given
        String expectedResult = "us-east-1a";
        given(awsMetadataApi.availabilityZoneEc2()).willReturn(expectedResult);

        // when
        String result = awsEc2Client.getAvailabilityZone();

        // then
        assertEquals(expectedResult, result);
    }