Add new lifecycle management methods in KiwiDropwizardLifecycles (#1175)

Add methods in KiwiDropwizardLifecycles to manage and only provide a
start or a stop action

Closes  #1163

src/main/java/org/kiwiproject/dropwizard/lifecycle/KiwiDropwizardLifecycles.java

@@ -1,5 +1,6 @@
 package org.kiwiproject.dropwizard.lifecycle;
 
+import com.google.common.util.concurrent.Runnables;
 import io.dropwizard.lifecycle.Managed;
 import io.dropwizard.lifecycle.setup.LifecycleEnvironment;
 import lombok.experimental.UtilityClass;
@@ -15,8 +16,8 @@ public class KiwiDropwizardLifecycles {
      * is {@code stopAction}, and attaches it to the given Dropwizard {@code lifecycle}.
      * <p>
      * Useful when you have some external object that has start and stop methods, but you don't want to clutter your
-     * code by creating an anonymous inner class just to specify the start and stop actions. For example if you have an
-     * ActiveMQ {@code PooledConnectionFactory} (which has {@code start} and {@code stop} methods) you can simply
+     * code by creating an anonymous inner class just to specify the start and stop actions. For example, if you have
+     * an ActiveMQ {@code PooledConnectionFactory} (which has {@code start} and {@code stop} methods) you can simply
      * call this method:
      * <p>
      * {@code KiwiDropwizardLifecycles.manage(lifecycle, () -> factory.start(), () -> factory.stop());}
@@ -42,4 +43,48 @@ public void stop() {
             }
         });
     }
+
+    /**
+     * Creates a Dropwizard {@link Managed} whose start action is {@code startAction},
+     * and attaches it to the given Dropwizard {@code lifecycle}.
+     * <p>
+     * Useful when you have some external object that has a start method, but you don't want to clutter your
+     * code by creating an anonymous inner class just to specify the start action. For example, if you have
+     * a monitoring class that needs to start when the application starts, you can ensure that happens
+     * using code like:
+     * <p>
+     * {@code KiwiDropwizardLifecycles.manage(lifecycle, () -> monitor.start());}
+     * <p>
+     * To make the code cleaner, use method references:
+     * <p>
+     * {@code KiwiDropwizardLifecycles.manage(lifecycle, monitor::start);}
+     *
+     * @param lifecycle   the lifecycle to manage
+     * @param startAction the action to run when Dropwizard starts the application
+     */
+    public static void manageOnlyStart(LifecycleEnvironment lifecycle, Runnable startAction) {
+        manage(lifecycle, startAction, Runnables.doNothing());
+    }
+
+    /**
+     * Creates a Dropwizard {@link Managed} whose stop action is {@code stopAction},
+     * and attaches it to the given Dropwizard {@code lifecycle}.
+     * <p>
+     * Useful when you have some external object that has a stop method, but you don't want to clutter your
+     * code by creating an anonymous inner class just to specify the stop action. For example, if you have
+     * an HTTP {@code Client} class that needs to stop when the application shuts down to ensure resources
+     * are properly closed, you can ensure that happens using code like:
+     * <p>
+     * {@code KiwiDropwizardLifecycles.manage(lifecycle, () -> client.close());}
+     * <p>
+     * To make the code cleaner, use method references:
+     * <p>
+     * {@code KiwiDropwizardLifecycles.manage(lifecycle, client::close);}
+     *
+     * @param lifecycle   the lifecycle to manage
+     * @param stopAction  the action to run when Dropwizard stops the application
+     */
+    public static void manageOnlyStop(LifecycleEnvironment lifecycle, Runnable stopAction) {
+        manage(lifecycle, Runnables.doNothing(), stopAction);
+    }
 }

src/test/java/org/kiwiproject/dropwizard/lifecycle/KiwiDropwizardLifecyclesTest.java

@@ -15,7 +15,7 @@
 class KiwiDropwizardLifecyclesTest {
 
     @Test
-    void testManageStart() throws Exception {
+    void shouldManageStart() throws Exception {
         var lifecycle = new LifecycleEnvironment(new MetricRegistry());
 
         var startCalled = new AtomicBoolean();
@@ -31,10 +31,11 @@ void testManageStart() throws Exception {
 
         managed.start();
         assertThat(startCalled.get()).isTrue();
+        assertThat(managed.isStarted()).isTrue();
     }
 
     @Test
-    void testManageStop() throws Exception {
+    void shouldManageStop() throws Exception {
         var lifecycle = new LifecycleEnvironment(new MetricRegistry());
 
         var stopCalled = new AtomicBoolean();
@@ -45,9 +46,56 @@ void testManageStop() throws Exception {
         var managedObjects = lifecycle.getManagedObjects();
         assertThat(managedObjects).hasSize(1);
 
+        // Make sure it's started, so that AbstractLifeCycle#stop will stop it
+        var managed = first(managedObjects);
+        managed.start();
+        assertThat(managed.isStarted())
+                .describedAs("Precondition: Managed object must be started")
+                .isTrue();
+
+        managed.stop();
+        assertThat(stopCalled.get()).isTrue();
+        assertThat(managed.isStopped()).isTrue();
+    }
+
+    @Test
+    void shouldManageOnlyStart() throws Exception {
+        var lifecycle = new LifecycleEnvironment(new MetricRegistry());
+
+        var startCalled = new AtomicBoolean();
+        Runnable startAction = () -> startCalled.set(true);
+
+        KiwiDropwizardLifecycles.manageOnlyStart(lifecycle, startAction);
+
+        var managedObjects = lifecycle.getManagedObjects();
+        assertThat(managedObjects).hasSize(1);
+
         var managed = first(managedObjects);
+        assertThat(managed.isStarted()).isFalse();
+
         managed.start();
+        assertThat(startCalled.get()).isTrue();
         assertThat(managed.isStarted()).isTrue();
+    }
+
+    @Test
+    void shouldManageOnlyStop() throws Exception {
+        var lifecycle = new LifecycleEnvironment(new MetricRegistry());
+
+        var stopCalled = new AtomicBoolean();
+        Runnable stopAction = () -> stopCalled.set(true);
+
+        KiwiDropwizardLifecycles.manageOnlyStop(lifecycle, stopAction);
+
+        var managedObjects = lifecycle.getManagedObjects();
+        assertThat(managedObjects).hasSize(1);
+
+        // Make sure it's started, so that AbstractLifeCycle#stop will stop it
+        var managed = first(managedObjects);
+        managed.start();
+        assertThat(managed.isStarted())
+                .describedAs("Precondition: Managed object must be started")
+                .isTrue();
 
         managed.stop();
         assertThat(stopCalled.get()).isTrue();