Add new "Collecting Logger", that can be activated to "collect" logs (e.g., in an internal list), for later access (e.g., by a test, to assert if things were logged).

qqq-backend-core/src/test/java/com/kingsrook/qqq/backend/core/logging/QCollectingLoggerTest.java

@@ -0,0 +1,92 @@
+/*
+ * QQQ - Low-code Application Framework for Engineers.
+ * Copyright (C) 2021-2024.  Kingsrook, LLC
+ * 651 N Broad St Ste 205 # 6917 | Middletown DE 19709 | United States
+ * contact@kingsrook.com
+ * https://github.com/Kingsrook/
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.kingsrook.qqq.backend.core.logging;
+
+
+import com.kingsrook.qqq.backend.core.BaseTest;
+import org.apache.logging.log4j.Level;
+import org.junit.jupiter.api.Test;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+
+/*******************************************************************************
+ ** Unit test for QCollectingLogger 
+ *******************************************************************************/
+class QCollectingLoggerTest extends BaseTest
+{
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   @Test
+   void test()
+   {
+      ClassThatLogsThings classThatLogsThings = new ClassThatLogsThings();
+      classThatLogsThings.logAnInfo("1");
+
+      QCollectingLogger collectingLogger = QLogger.activateCollectingLoggerForClass(ClassThatLogsThings.class);
+      classThatLogsThings.logAnInfo("2");
+      classThatLogsThings.logAWarn("3");
+      QLogger.deactivateCollectingLoggerForClass(ClassThatLogsThings.class);
+
+      classThatLogsThings.logAWarn("4");
+
+      assertEquals(2, collectingLogger.getCollectedMessages().size());
+
+      assertThat(collectingLogger.getCollectedMessages().get(0).getMessage()).contains("""
+         "message":"2",""");
+      assertEquals("2", collectingLogger.getCollectedMessages().get(0).getMessageAsJSONObject().getString("message"));
+      assertEquals(Level.INFO, collectingLogger.getCollectedMessages().get(0).getLevel());
+
+      assertThat(collectingLogger.getCollectedMessages().get(1).getMessage()).contains("""
+         "message":"3",""");
+      assertEquals(Level.WARN, collectingLogger.getCollectedMessages().get(1).getLevel());
+      assertEquals("3", collectingLogger.getCollectedMessages().get(1).getMessageAsJSONObject().getString("message"));
+   }
+
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   public static class ClassThatLogsThings
+   {
+      private static final QLogger LOG = QLogger.getLogger(ClassThatLogsThings.class);
+
+      /*******************************************************************************
+       **
+       *******************************************************************************/
+      private void logAnInfo(String message)
+      {
+         LOG.info(message);
+      }
+
+      /*******************************************************************************
+       **
+       *******************************************************************************/
+      private void logAWarn(String message)
+      {
+         LOG.warn(message);
+      }
+   }
+
+}