feat: Add example unit test for running Activiti 7 process

[igdianov]

This PR adds example how to create a unit test for Activiti7 process with Cloud Connector task using Spring Test Integration Binder: https://cloud.spring.io/spring-cloud-static/spring-cloud-stream/2.1.0.RELEASE/multi/multi__testing.html#spring_integration_test_binder

Fixes Activiti/Activiti#2865

[igdianov]

@slamkalukas I have created a PR with example unit test for Activiti7 process: #315. Let me know if you have any questions

[erdemedeiros]

Thank you @igdianov that's a useful example. See my questions below.

[erdemedeiros]

Wouldn't be easier to add the dependency to activiti-cloud-starter-connector in test scope so you can use the provided IntegrationResultSender?
activiti-cloud-starter-connector is also bringing IntegrationResultBuilder: https://github.com/Activiti/ttc-connectors-dummytwitter/blob/master/src/main/java/org/activiti/cloud/connectors/twitter/connectors/TweetConnector.java#L60

[igdianov]

@erdemedeiros I have tried to add starter connector dependency in test scope. It is causing a problem with overriding bean definitions:

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
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 :: Spring Boot ::        (v2.1.2.RELEASE)

2019-08-26 00:28:16.265  INFO [-,,,] 15596 --- [           main] o.a.c.r.RuntimeBundleApplicationTest     : No active profile set, falling back to default profiles: default
2019-08-26 00:28:17.037  INFO [-,,,] 15596 --- [           main] o.s.c.a.ConfigurationClassParser         : Properties location [classpath:/activiti-audit-producer.properties] not resolvable: class path resource [activiti-audit-producer.properties] cannot be opened because it does not exist
2019-08-26 00:28:17.235  INFO [-,,,] 15596 --- [           main] o.s.c.a.ConfigurationClassParser         : Properties location [classpath:/activiti-audit-producer.properties] not resolvable: class path resource [activiti-audit-producer.properties] cannot be opened because it does not exist
2019-08-26 00:28:18.653  WARN [-,,,] 15596 --- [           main] o.s.w.c.s.GenericWebApplicationContext   : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.support.BeanDefinitionOverrideException: Invalid bean definition with name 'keycloakPreAuthActionsFilter' defined in class path resource [org/activiti/cloud/services/identity/keycloak/config/RuntimeBundleSecurityAutoConfiguration.class]: Cannot register bean definition [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=runtimeBundleSecurityAutoConfiguration; factoryMethodName=keycloakPreAuthActionsFilter; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/activiti/cloud/services/identity/keycloak/config/RuntimeBundleSecurityAutoConfiguration.class]] for bean 'keycloakPreAuthActionsFilter': There is already [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=commonSecurityAutoConfiguration; factoryMethodName=keycloakPreAuthActionsFilter; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/activiti/cloud/services/common/security/keycloak/config/CommonSecurityAutoConfiguration.class]] bound.
2019-08-26 00:28:18.663  INFO [-,,,] 15596 --- [           main] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-08-26 00:28:18.668 ERROR [-,,,] 15596 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
APPLICATION FAILED TO START
***************************

Description:

The bean 'keycloakPreAuthActionsFilter', defined in class path resource [org/activiti/cloud/services/identity/keycloak/config/RuntimeBundleSecurityAutoConfiguration.class], could not be registered. A bean with that name has already been defined in class path resource [org/activiti/cloud/services/common/security/keycloak/config/CommonSecurityAutoConfiguration.class] and overriding is disabled.

Action:

Consider renaming one of the beans or enabling overriding by setting spring.main.allow-bean-definition-overriding=true

[igdianov]

After enabling bean override, it blows up with the error due to component scan:

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-08-26 00:38:47.794 ERROR [-,,,] 37240 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'commonSecurityAutoConfiguration': Unsatisfied dependency expressed through field 'keycloakConfigResolver'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'runtimeBundleSecurityAutoConfiguration': Unsatisfied dependency expressed through field 'keycloakConfigResolver'; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'KeycloakConfigResolver': Requested bean is currently in creation: Is there an unresolvable circular reference?
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:596)

[igdianov]

@erdemedeiros The activiti-cloud-starter-connector module component scan problem is fixed now. I have updated unit test example to use IntegrationResultBuilder and removed hacks from previous commits.