add the ability to use inmem journal using the fluent builder

pom.xml

@@ -28,13 +28,21 @@
         <junit.version>4.11</junit.version>
         <akka.version>2.3.4</akka.version>
         <slf4j.version>1.7.7</slf4j.version>
+        <akka-persistence-inmemory.version>0.2.1</akka-persistence-inmemory.version>
     </properties>
     <dependencies>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
             <version>${junit.version}</version>
         </dependency>
+        <dependency>
+            <groupId>com.github.michaelpisula</groupId>
+            <artifactId>akka-persistence-inmemory_2.10</artifactId>
+            <version>${akka-persistence-inmemory.version}</version>
+            <scope>runtime</scope>
+            <optional>true</optional>
+        </dependency>
         <dependency>
             <groupId>com.typesafe.akka</groupId>
             <artifactId>akka-actor_2.10</artifactId>

src/main/java/org/zapodot/akka/junit/ActorSystemRuleBuilder.java

@@ -60,6 +60,7 @@ public ActorSystemRuleBuilder enableEventLogging() {
 
     /**
      * Enables debug logging of receive events for all actors, i.e sets "akka.actor.debug.receive = on"
+     *
      * @return
      */
     public ActorSystemRuleBuilder enableReceiveDebugLogging() {
@@ -69,6 +70,7 @@ public ActorSystemRuleBuilder enableReceiveDebugLogging() {
 
     /**
      * Enables lifecycle debug logging by setting "akka.actor.debug.lifecycle = on"
+     *
      * @return
      */
     public ActorSystemRuleBuilder enableLifecycleDebugLogging() {
@@ -78,13 +80,32 @@ public ActorSystemRuleBuilder enableLifecycleDebugLogging() {
 
     /**
      * Sets the global log level for Akka to "debug", i.e sets "akka.loglevel= debug"
+     *
      * @return
      */
     public ActorSystemRuleBuilder setEventLogLevelDebug() {
         setOrAddConfiguration(ConfigFactory.parseString("akka.loglevel = debug"));
         return this;
     }
 
+    /**
+     * Enables the Inmemory Journal which is very useful for testing event sourced actors
+     *
+     * @return
+     * @see <a href="https://github.com/michaelpisula/akka-journal-inmemory/">InMemory journal project page</a>
+     */
+    public ActorSystemRuleBuilder enableInmemoryJournal() {
+        try {
+            getClass().getClassLoader().loadClass("akka.persistence.journal.inmemory.InMemoryJournal");
+        } catch (ClassNotFoundException e) {
+            throw new IllegalStateException(
+                    "Could not find the InMemoryJournal class on the classpath, did you add the akka-persistence-inmemory dependency?",
+                    e);
+        }
+        setOrAddConfiguration(ConfigFactory.parseString("akka.persistence.journal.plugin = \"in-memory-journal\""));
+        return this;
+    }
+
     private void setOrAddConfiguration(final Config config) {
         if (this.config == null) {
             this.config = config;
@@ -103,7 +124,7 @@ public ActorSystemRuleBuilder setConfigFromString(final String configString) {
     }
 
     Config currentConfig() {
-        if(this.config == null) {
+        if (this.config == null) {
             return ConfigFactory.empty();
         } else {
             return ConfigFactory.empty().withFallback(config);

src/test/java/org/zapodot/akka/junit/ActorSystemRuleBuilderTest.java

@@ -73,4 +73,11 @@ public void testEnableLifecycleAndReceiveDebugLogging() throws Exception {
         assertEquals("on", config.getString("akka.actor.debug.receive"));
 
     }
+
+    @Test
+    public void testEnableInMemoryJournal() throws Exception {
+
+        final Config config = ActorSystemRule.builder().enableInmemoryJournal().currentConfig();
+        assertEquals("in-memory-journal", config.getString("akka.persistence.journal.plugin"));
+    }
 }