retrofit

Class MockRestAdapter

java.lang.Object

retrofit.MockRestAdapter

public final class MockRestAdapter
extends Object

Wraps mock implementations of API interfaces so that they exhibit the delay and error characteristics of a real network.

Because APIs are defined as interfaces, versions of the API that use mock data can be created by simply implementing the API interface on a class. These mock implementations execute synchronously which is a large deviation from the behavior of those backed by an API call over the network. By wrapping the mock instances using this class, the interface will still use mock data but exhibit the delays and errors that a real network would face.

Create an API interface and a mock implementation of it.

   public interface UserService {
     @GET("/user/{id}")
     User getUser(@Path("id") String userId);
   }
   public class MockUserService implements UserService {
     @Override public User getUser(String userId) {
       return new User("Jake");
     }
   }
 

Given a RestAdapter an instance of this class can be created by calling from(retrofit.RestAdapter).

   MockRestAdapter mockRestAdapter = MockRestAdapter.from(restAdapter);
 

Instances of this class should be used as a singleton so that the behavior of every mock service is consistent.

Rather than using the MockUserService directly, pass it through the create method.

   UserService service = mockRestAdapter.create(UserService.class, new MockUserService());
 

The returned UserService instance will now behave like it is happening over the network while allowing the mock implementation to be written synchronously.

HTTP errors can be simulated in your mock services by throwing an instance of MockHttpException. This should be done for both synchronous and asynchronous methods. Do not call the failure() method of a callback.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	MockRestAdapter.ValueChangeListener A listener invoked when the network behavior values for a MockRestAdapter change.

Method Summary

Modifier and Type	Method and Description
int	calculateDelayForCall() Get the delay (in milliseconds) that should be used for delaying a network call response.
int	calculateDelayForError() Get the delay (in milliseconds) that should be used for triggering a network error.
boolean	calculateIsFailure() Randomly determine whether this call should result in a network failure.
<T> T	create(Class<T> service, T mockService) Wrap the supplied mock implementation of a service so that it exhibits the delay and error characteristics of a real network.
static MockRestAdapter	from(RestAdapter restAdapter) Create a new MockRestAdapter which will act as a factory for mock services.
long	getDelay() The network round trip delay, in milliseconds
int	getErrorPercentage() The percentage of calls to calculateIsFailure() that return true.
int	getVariancePercentage() The plus-or-minus variance percentage of the network round trip delay.
void	setDelay(long delayMs) Set the network round trip delay, in milliseconds.
void	setErrorPercentage(int errorPct) Set the percentage of calls to calculateIsFailure() that return true.
void	setValueChangeListener(MockRestAdapter.ValueChangeListener listener) Set a listener to be notified when any mock value changes.
void	setVariancePercentage(int variancePct) Set the plus-or-minus variance percentage of the network round trip delay.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

from

public static MockRestAdapter from(RestAdapter restAdapter)

Create a new MockRestAdapter which will act as a factory for mock services. Some of the configuration of the supplied RestAdapter will be used generating mock behavior.

setValueChangeListener

public void setValueChangeListener(MockRestAdapter.ValueChangeListener listener)

Set a listener to be notified when any mock value changes.

setDelay

public void setDelay(long delayMs)

Set the network round trip delay, in milliseconds.

getDelay

public long getDelay()

The network round trip delay, in milliseconds

setVariancePercentage

public void setVariancePercentage(int variancePct)

Set the plus-or-minus variance percentage of the network round trip delay.

getVariancePercentage

public int getVariancePercentage()

The plus-or-minus variance percentage of the network round trip delay.

setErrorPercentage

public void setErrorPercentage(int errorPct)

Set the percentage of calls to calculateIsFailure() that return true.

getErrorPercentage

public int getErrorPercentage()

The percentage of calls to calculateIsFailure() that return true.

calculateIsFailure

public boolean calculateIsFailure()

Randomly determine whether this call should result in a network failure.

This method is exposed for implementing other, non-Retrofit services which exhibit similar network behavior. Retrofit services automatically will exhibit network behavior when wrapped using create(Class, Object).

calculateDelayForError

public int calculateDelayForError()

Get the delay (in milliseconds) that should be used for triggering a network error.

Because we are triggering an error, use a random delay between 0 and three times the normal network delay to simulate a flaky connection failing anywhere from quickly to slowly.

This method is exposed for implementing other, non-Retrofit services which exhibit similar network behavior. Retrofit services automatically will exhibit network behavior when wrapped using create(Class, Object).

calculateDelayForCall

public int calculateDelayForCall()

Get the delay (in milliseconds) that should be used for delaying a network call response.

This method is exposed for implementing other, non-Retrofit services which exhibit similar network behavior. Retrofit services automatically will exhibit network behavior when wrapped using create(Class, Object).

create

public <T> T create(Class<T> service,
                    T mockService)

Wrap the supplied mock implementation of a service so that it exhibits the delay and error characteristics of a real network.

See Also:

setDelay(long), setVariancePercentage(int), setErrorPercentage(int)