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Validating EventBus Subscriber Implementation in greenrobot/EventBus

This test suite validates the legal subscriber patterns and behaviors in the EventBus library, focusing on proper registration, event handling, and subscriber method requirements. It ensures the EventBus properly handles valid subscriber implementations while maintaining expected functionality.

Test Coverage Overview

The test suite provides comprehensive coverage of legal EventBus subscriber implementations and behavior.

Key areas tested include:

Basic subscriber registration and unregistration
Event posting and handling verification
Abstract class implementation testing
Event count validation

Implementation Analysis

The testing approach employs JUnit framework for systematic verification of EventBus subscriber functionality.

The implementation uses inheritance from AbstractEventBusTest and leverages annotations like @Subscribe and @Test to structure the test cases. The code demonstrates proper event tracking and verification patterns specific to EventBus architecture.

Technical Details

Testing infrastructure includes:

JUnit testing framework
EventBus core library
Custom AbstractEventBusTest base class
Event tracking mechanisms
Assert statements for validation

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Clear test method naming conventions
Proper test isolation through register/unregister cycles
Effective use of inheritance for shared test functionality
Comprehensive verification of both positive and negative cases
Clean separation of concerns between test cases

greenrobot/eventbus

EventBusTestJava/src/main/java/org/greenrobot/eventbus/EventBusSubscriberLegalTest.java

            
/*
 * Copyright (C) 2012-2016 Markus Junginger, greenrobot (http://greenrobot.org)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.greenrobot.eventbus;

import org.junit.Test;

import static org.junit.Assert.assertEquals;

/**
 * @author Markus Junginger, greenrobot
 */
public class EventBusSubscriberLegalTest extends AbstractEventBusTest {

    @Test
    public void testSubscriberLegal() {
        eventBus.register(this);
        eventBus.post("42");
        eventBus.unregister(this);
        assertEquals(1, eventCount.intValue());
    }

    // With build time verification, some of these tests are obsolete (and cause problems during build)
//    public void testSubscriberNotPublic() {
//        try {
//            eventBus.register(new NotPublic());
//            fail("Registration of ilegal subscriber successful");
//        } catch (EventBusException e) {
//            // Expected
//        }
//    }

//    public void testSubscriberStatic() {
//        try {
//            eventBus.register(new Static());
//            fail("Registration of ilegal subscriber successful");
//        } catch (EventBusException e) {
//            // Expected
//        }
//    }

    public void testSubscriberLegalAbstract() {
        eventBus.register(new AbstractImpl());

        eventBus.post("42");
        assertEquals(1, eventCount.intValue());
    }

    @Subscribe
    public void onEvent(String event) {
        trackEvent(event);
    }

//    public static class NotPublic {
//        @Subscribe
//        void onEvent(String event) {
//        }
//    }

    public static abstract class Abstract {
        @Subscribe
        public abstract void onEvent(String event);
    }

    public class AbstractImpl extends Abstract {

        @Override
        @Subscribe
        public void onEvent(String event) {
            trackEvent(event);
        }

    }

//    public static class Static {
//        @Subscribe
//        public static void onEvent(String event) {
//        }
//    }

}