Merge pull request #147 from safarmer/appender-from-client

Allow a BugsnagAppender to be created from an existing client.

Author: fractalwrench

bugsnag/src/main/java/com/bugsnag/BugsnagAppender.java

@@ -80,9 +80,26 @@ public class BugsnagAppender extends UnsynchronizedAppenderBase<ILoggingEvent> {
     /** Bugsnag client. */
     private Bugsnag bugsnag = null;
 
+    /** Creates an appender from an existing Bugsnag client. */
+    public BugsnagAppender(Bugsnag bugsnag) {
+        super();
+        this.bugsnag = bugsnag;
+    }
+
+    /**
+     * Default constructor used by Logback to create a Bugsnag appender that will create it's own
+     * client when required.
+     */
+    @SuppressWarnings("unused")
+    public BugsnagAppender() {
+        this(null);
+    }
+
     @Override
     public void start() {
-        this.bugsnag = createBugsnag();
+        if (bugsnag == null) {
+            this.bugsnag = createBugsnag();
+        }
         super.start();
     }
 

bugsnag/src/test/java/com/bugsnag/AppenderTest.java

@@ -346,6 +346,19 @@ public void testSplit() {
         assertArrayEquals(expected, appender.split("one,two,three").toArray());
     }
 
+    @Test
+    public void testCreateFromExistingClient() {
+        Bugsnag client = new Bugsnag("testApiKey");
+        BugsnagAppender appender = new BugsnagAppender(client);
+        // Make sure configuration changes are not passed through to the provided client.
+        appender.setApiKey("newApiKey");
+        // Make sure a new client is not created when starting the appender.
+        appender.start();
+
+        assertEquals(client, appender.getClient());
+        assertEquals("testApiKey", appender.getClient().getConfig().apiKey);
+    }
+
     private StackTraceElement changeClassName(StackTraceElement element, String className) {
         return new StackTraceElement(className,
                 element.getFileName(),