Thank you very much Ingo. It was exactly the solution. It works with:
Here is the configuration OK for my Unit test:
<bean id="processEngineConfiguration" class="org.camunda.bpm.engine.impl.cfg.StandaloneInMemProcessEngineConfiguration">
<!-- <bean id="processEngineConfiguration" class="org.camunda.bpm.extension.process_test_coverage.junit.rules.ProcessCoverageInMemProcessEngineConfiguration"> -->
<property name="history" value="audit" />
<property name="databaseSchemaUpdate" value="true" />
<property name="jobExecutorActivate" value="false" />
<property name="defaultSerializationFormat" value="application/json" />
<!--<property name="expressionManager">
<bean class="org.camunda.bpm.engine.test.mock.MockExpressionManager" />
</property>-->
<!-- engine plugins -->
<property name="processEnginePlugins">
<list>
<!--<ref bean="connectProcessEnginePlugin" />-->
<ref bean="spinProcessEnginePlugin" />
</list>
</property>
<!-- <property name="idGenerator">
<bean class="org.camunda.bpm.engine.impl.persistence.StrongUuidGenerator"/>
</property> -->
</bean>
<!-- engine plugin beans -->
<!-- <bean id="connectProcessEnginePlugin" class="org.camunda.connect.plugin.impl.ConnectProcessEnginePlugin" /> -->
<bean id="spinProcessEnginePlugin" class="org.camunda.spin.plugin.impl.SpinProcessEnginePlugin" />
</beans>