### Question:
SLAAgreementHelper { public String getPowerUnitsPerOVFId(String ovfId) { return getUnits("Power_Usage_for_" + ovfId); } SLAAgreementHelper(String slaString); SLA getSla(); double getPowerUsagePerApp(); String getPowerUsagePerAppUnits(); double getPowerUsagePerOVFId(String ovfId); String getPowerUnitsPerOVFId(String ovfId);  }### Answer:
@Test public void getPowerUnitsPerOVFId() { SLAAgreementHelper helper = new SLAAgreementHelper(slaAgreement2Text); String units = helper.getPowerUnitsPerOVFId("jboss"); assertEquals("Watt", units); helper = new SLAAgreementHelper(slaAgreementText); units = helper.getPowerUnitsPerOVFId("jboss"); assertNull(units); }