Groovy metaclass, mocking a service method that has throws clause - grails

I have an abstract service:
abstract class ParentService {
abstract Map someMethod() throws NumberFormatException
}
And another service that extends above class:
class ChildService extends ParentService {
#Override
Map someMethod() throws NumberFormatException {
//Business Logic
}
}
I want to mock someMethod() using groovy metaClass. I need to mock this method for writing test cases for ChildService. This is what I have done for mocking:
ChildService.metaClass.someMethod = { -> "Mocked method" }
But this is not working and the call always executes actual method from the service. What needs to be done here? Am I missing something?
Please Note that I have to mock just one method not the entire service.

Maybe you could just mock method on instance?
def child = new ChildService()
child.metaClass.someMethod = { -> "Mocked method" }

Related

Avoid Type casting on Factory Pattern

I am writing a payment service class in Dart that wraps more than 1 payment provider. The expectation is the caller can simply switch one to another without any hassle.
Let's imagine I have classes like this:
enum PaymentProvider { providerA, providerB }
abstract class PaymentService {
void processPayment(Order oder);
}
class PaymentServiceA implements PaymentService {
final String appKey;
final String merchantId;
PaymentServiceA(this.appKey, this.merchantId);
#override
void processPayment(Order oder) {
// concrete implementation to process payment
}
String getVoucher() {
// return voucher code
}
}
class PaymentServiceB implements PaymentService {
final PaymentBOptions options;
PaymentServiceB(this.options);
#override
void processPayment(Order oder) {
// concrete implementation to process payment
}
List<PaymentBHistory> getPaymentHistory() {
// return payment history
}
}
class PaymentBOptions {
final bool sendEmailReceipt;
final Function()? successCallback;
PaymentBOptions(this.sendEmailReceipt, this.successCallback);
}
So here PaymentServiceA and PaymentServiceB have same method (processPayment) so we can create base class PaymentService and let them implements this base class.
However as you can see each of them also has different constructor parameter and specific methods.
How is the best approach to create PaymentService that wrap more than 1 provider like this?
I was trying to use factory pattern like this:
abstract class PaymentService {
factory PaymentService(PaymentProvider provider) {
switch(provider) {
case PaymentProvider.providerA:
String appKey = "xxxx";
String merchantId = "123"
return PaymentServiceA(appKey, merchantId);
case PaymentProvider.providerB:
PaymentBOptions options = PaymentBOptions(() {
});
return PaymentServiceB(options);
}
}
void processPayment(Order order);
}
But I don't think this is the good practice because:
If we create PaymentServiceA or PaymentServiceB instance using PaymentService factory method it will return as PaymentService and we need to cast to appropriate class in order to access specific PaymentService method.
We can't supply specific constructor parameter of PaymentServiceA or PaymentServiceB outside PaymentService abstract class via factory constructor.
Any idea on how is the best practice and what's the suitable design pattern when facing this kind of scenario?
Thanks.

Grails 4 service not being injected inside Grails Data Service

This is about a Grails service injected into a Data Service. The problem is that the injected service is null at runtime. Here is an example.
class MessagingService {
def sendEmail(String message) {
...
}
}
interface IFlowService {
...
}
#Service(Flow)
abstract class FlowService implements IFlowService {
MessagingService messagingService
void sendFoo() {
messagingService.sendEmail(message)
}
}
FlowService and MessagingService both reside under grails-app/services.
When FlowService calls sendEmail there is an NPE because messagingService is null.
MessagingService is hand-written and is not associated with a domain.
This project uses Grails 4.0.10 and the issue occurred several times. When the usual Gails magic (i.e. injection) didn't work I solved the first one or two issues with kludges, you know, just to avoid getting stuck.
Now it seems to me the issue is quite predictable, it happens every time I write a service not associated with a domain. Did I miss something in the documentation? What is the appropriate way to handle this?
Kludge: To get around the issue I include a method sayHi in the problematic service. It just logs a debug message. I invoke sayHi from BootStrap to check that it works. It does, surprisingly. Then I add code in BootStrap to assign the service to the supposedly injected property in the service. [Shudder]
I tried to reproduce the same-
interface IFlowService {
}
#Service(Flow)
abstract class FlowService implements IFlowService {
MessagingService messagingService
void hello() {
println "hello"
messagingService.hi() // <- NPE
}
}
class MessagingService {
void hi() {
println "hi"
}
}
This seems to be a bug to be in Grails. But you can easily solve this (probably as a workaround) by just adding #Autowired in the service-
import org.springframework.beans.factory.annotation.Autowired
#Service(Flow)
abstract class FlowService implements IFlowService {
#Autowired
MessagingService messagingService
void hello() {
println "hello"
messagingService.hi() // <- No NPE
}
}
It prints-

How to test whether an instance method is called from within another instance method in Grails 3 using Spock

Using Grails 3.2.8 and the Spock framework for testing, given the following controller class:
class SomeController {
def doSomething() {
// do a few things, then:
someOtherMethod()
}
protected void someOtherMethod() {
// do something here, but I don't care
}
}
How can I test the doSomething() method to make sure someOtherMethod() is called exactly once?
This is my attempt that failed:
#TestFor(SomeController)
class SomeControllerSpec extends Specification {
void "Test that someOtherMethod() is called once inside doSomething()"() {
when:
controller.doSomething()
then:
1 * controller.someOtherMethod(_)
}
}
Error message:
Too few invocations for:
1 * controller.someOtherMethod(_) (0 invocations)
Note: Imports have been omitted to focus on the problem at hand
You can't do that as controller is not a mocked object. Instead, you need to use metaclass like this:
#TestFor(SomeController)
class SomeControllerSpec extends Specification {
void "Test that someOtherMethod() is called once inside doSomething()"() {
given:
Integer callsToSomeOtherMethod = 0
controller.metaClass.someOtherMethod = {
callsToSomeOtherMethod++
}
when:
controller.doSomething()
then:
callsToSomeOtherMethod == 1
}
}

Abstract methods in Dart API reference

Many methods like complete in class Completer are marked "abstract", but in fact It can be directly invoked without being implemented. I'm really confused. Could anyone help me?
Yes, this can be a bit confusing. While abstract classes cannot be instantiated, it is possible to make them appear to be instantiable by defining a factory constructor. This is what Completer, Future and other abstract classes do:
abstract class Completer<T> {
factory Completer() => new _CompleterImpl<T>();
...
}
You can then invoke methods on the object created by the factory constructor. In the example above, factory Completer() returns a new _CompleterImpl object. Look at the (truncated) code of that class:
class _CompleterImpl<T> implements Completer<T> {
final _FutureImpl<T> _futureImpl;
_CompleterImpl() : _futureImpl = new _FutureImpl() {}
Future<T> get future {
return _futureImpl;
}
void complete(T value) {
_futureImpl._setValue(value);
}
...
}
and you see complete(); that is the method being invoked.

GroovyInterceptable (AOP) and closures

I've got a grails app with Service classes that inherit from Groovy's GroovyInterceptable:
class customerSerrvice implements GroovyInterceptable {
private List<Customer> customers
def invokeMethod(String name, args) {
log.debug "=======>INVOKING method [$name] with args:$args"
}
void foo() {
customers.each { doSomething(it) }
}
void doSomething(Customer cust) { log.debug "doSomething invoked with $cust" }
}
The above is a greatly simplified representation, but it gives you the idea. If I call foo() or doSomething() directly from another class, the invokeMethod gets called like it is supposed to. However, when foo() calls doSomething(), that call is not intercepted in invokeMethod.
If I change from
customers.each { doSomething(it) }
to
for(Customer cust: customers) { doSomething(cust) }
then the invokeMethod gets called just fine.
So is there something about closures and GroovyInterceptable that don't go together? Is there any way to get the invokeMethod to work with closures short of changing them all out?
Thanks
Confirmed as a bug, old link:
http://jira.codehaus.org/browse/GROOVY-4610, new link:
https://issues.apache.org/jira/browse/GROOVY-4610

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