### Question:
ModifyResource extends AbstractCommand<ModifyResource> implements PolicyModifyCommand<ModifyResource> { @Deprecated public static ModifyResource of(final String policyId, final Label label, final Resource resource, final DittoHeaders dittoHeaders) { return of(PolicyId.of(policyId), label, resource, dittoHeaders); } private  ModifyResource(final PolicyId policyId,
            final Label label,
            final Resource resource,
            final DittoHeaders dittoHeaders); @Deprecated static ModifyResource of(final String policyId,
            final Label label,
            final Resource resource,
            final DittoHeaders dittoHeaders); static ModifyResource of(final PolicyId policyId,
            final Label label,
            final Resource resource,
            final DittoHeaders dittoHeaders); static ModifyResource fromJson(final String jsonString, final DittoHeaders dittoHeaders); static ModifyResource fromJson(final JsonObject jsonObject, final DittoHeaders dittoHeaders); Label getLabel(); Resource getResource(); @Override PolicyId getEntityId(); @Override Optional<JsonValue> getEntity(final JsonSchemaVersion schemaVersion); @Override JsonPointer getResourcePath(); @Override Category getCategory(); @Override ModifyResource setDittoHeaders(final DittoHeaders dittoHeaders); @SuppressWarnings("squid:MethodCyclomaticComplexity") @Override boolean equals(@Nullable final Object obj); @SuppressWarnings("squid:S109") @Override int hashCode(); @Override String toString(); static final String NAME; static final String TYPE; }### Answer:
@Test(expected = NullPointerException.class) public void tryToCreateInstanceWithNullPolicyId() { ModifyResource.of((PolicyId) null, TestConstants.Policy.LABEL, TestConstants.Policy.RESOURCE, TestConstants.EMPTY_DITTO_HEADERS); }
@Test(expected = PolicyIdInvalidException.class) public void tryToCreateInstanceWithNullPolicyIdString() { ModifyResource.of((String) null, TestConstants.Policy.LABEL, TestConstants.Policy.RESOURCE, TestConstants.EMPTY_DITTO_HEADERS); }
@Test public void tryToCreateInstanceWithInvalidPolicyId() { assertThatExceptionOfType(PolicyIdInvalidException.class) .isThrownBy(() -> ModifyResource.of("undefined", TestConstants.Policy.LABEL, TestConstants.Policy.RESOURCE, TestConstants.EMPTY_DITTO_HEADERS)); }
@Test(expected = NullPointerException.class) public void tryToCreateInstanceWithNullLabel() { ModifyResource.of(TestConstants.Policy.POLICY_ID, null, TestConstants.Policy.RESOURCE, TestConstants.EMPTY_DITTO_HEADERS); }
@Test(expected = NullPointerException.class) public void tryToCreateInstanceWithNullResource() { ModifyResource.of(TestConstants.Policy.POLICY_ID, TestConstants.Policy.LABEL, null, TestConstants.EMPTY_DITTO_HEADERS); }
@Test public void toJsonReturnsExpected() { final ModifyResource underTest = ModifyResource.of(TestConstants.Policy.POLICY_ID, TestConstants.Policy.LABEL, TestConstants.Policy.RESOURCE, TestConstants.EMPTY_DITTO_HEADERS); final JsonObject actualJson = underTest.toJson(FieldType.regularOrSpecial()); assertThat(actualJson).isEqualTo(KNOWN_JSON); }