Create tests for admin commands

src/test/java/fr/xephi/authme/TestHelper.java

@@ -1,10 +1,15 @@
 package fr.xephi.authme;
 
+import fr.xephi.authme.command.CommandService;
+import org.mockito.ArgumentCaptor;
+
 import java.io.File;
 import java.net.URL;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 
+import static org.mockito.Mockito.verify;
+
 /**
  * AuthMe test utilities.
  */
@@ -47,4 +52,18 @@ public final class TestHelper {
         return url;
     }
 
+    /**
+     * Execute a {@link Runnable} passed to a mock's {@link CommandService#runTaskAsynchronously} method.
+     * Note that calling this method expects that there be a runnable sent to the method and will fail
+     * otherwise.
+     *
+     * @param service The mock service
+     */
+    public static void runInnerRunnable(CommandService service) {
+        ArgumentCaptor<Runnable> captor = ArgumentCaptor.forClass(Runnable.class);
+        verify(service).runTaskAsynchronously(captor.capture());
+        Runnable runnable = captor.getValue();
+        runnable.run();
+    }
+
 }