Add testing support for logging and capturing log events.

Adds a custom, SLF4J, Logback Appender named 'TestAppender' to listen for and record log events (ILoggingEvent) in a Stack.

spring-data-geode-test/src/main/java/org/springframework/data/gemfire/tests/logging/slf4j/logback/TestAppender.java

@@ -0,0 +1,76 @@
+/*
+ *  Copyright 2019 the original author or authors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       https://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ *  or implied. See the License for the specific language governing
+ *  permissions and limitations under the License.
+ */
+package org.springframework.data.gemfire.tests.logging.slf4j.logback;
+
+import static org.springframework.data.gemfire.util.RuntimeExceptionFactory.newIllegalStateException;
+
+import java.util.Optional;
+import java.util.Stack;
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.springframework.util.StringUtils;
+
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.core.Appender;
+import ch.qos.logback.core.AppenderBase;
+
+/**
+ * The {@link TestAppender} class is a SLF4J, Logback {@link Appender} implementation used for testing purposes.
+ *
+ * @author John Blum
+ * @see java.util.Stack
+ * @see ch.qos.logback.core.Appender
+ * @see ch.qos.logback.core.AppenderBase
+ * @since 0.0.5.RELEASE
+ */
+@SuppressWarnings("unused")
+public class TestAppender extends AppenderBase<ILoggingEvent> implements Appender<ILoggingEvent> {
+
+	private static final AtomicReference<TestAppender> INSTANCE = new AtomicReference<>(null);
+
+	private static final Stack<String> logMessages = new Stack<>();
+
+	public static TestAppender getInstance() {
+
+		return Optional.ofNullable(INSTANCE.get())
+			.orElseThrow(() -> newIllegalStateException("[%s] was not properly configured",
+				TestAppender.class.getName()));
+	}
+
+	public TestAppender() {
+		INSTANCE.compareAndSet(null, this);
+	}
+
+	@Override
+	protected void append(ILoggingEvent event) {
+
+		Optional.ofNullable(event)
+			.map(ILoggingEvent::getFormattedMessage)
+			.filter(StringUtils::hasText)
+			.ifPresent(logMessages::push);
+	}
+
+	public String lastLogMessage() {
+
+		synchronized (logMessages) {
+			return logMessages.empty() ? null : logMessages.pop();
+		}
+	}
+
+	public void clear() {
+		logMessages.clear();
+	}
+}

spring-data-geode-test/src/test/java/org/springframework/data/gemfire/tests/logging/slf4j/logback/TestAppenderUnitTests.java

@@ -0,0 +1,71 @@
+/*
+ *  Copyright 2019 the original author or authors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       https://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ *  or implied. See the License for the specific language governing
+ *  permissions and limitations under the License.
+ */
+package org.springframework.data.gemfire.tests.logging.slf4j.logback;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Unit Tests for {@link TestAppender}.
+ *
+ * @author John Blum
+ * @see org.junit.Test
+ * @see org.slf4j.Logger
+ * @see org.springframework.data.gemfire.tests.logging.slf4j.logback.TestAppender
+ * @since 0.0.5.RELEASE
+ */
+public class TestAppenderUnitTests {
+
+	private static final Logger logger = LoggerFactory.getLogger(TestAppenderUnitTests.class);
+
+	@Test
+	public void logEventsAppendedCorrectly() {
+
+		TestAppender testAppender = TestAppender.getInstance();
+
+		assertThat(testAppender).isNotNull();
+		assertThat(testAppender.lastLogMessage()).isNull();
+
+		LoggableObject object = new LoggableObject();
+
+		object.logAnError();
+		object.logAnInfoMessage();
+		object.logAWarning();
+
+		assertThat(testAppender.lastLogMessage()).isEqualTo("WARN TEST");
+		assertThat(testAppender.lastLogMessage()).isEqualTo("ERROR TEST");
+		assertThat(testAppender.lastLogMessage()).isNull();
+	}
+
+	static class LoggableObject {
+
+		public void logAnError() {
+			logger.error("ERROR TEST");
+		}
+
+		public void logAnInfoMessage() {
+			logger.info("INFO TEST");
+		}
+
+		public void logAWarning() {
+			logger.warn("WARN TEST");
+		}
+	}
+}

spring-data-geode-test/src/test/resources/logback.xml

@@ -11,7 +11,7 @@
 
     <appender name="nop" class="ch.qos.logback.core.helpers.NOPAppender"/>
 
-    <appender name="testAppender" class="org.springframework.data.gemfire.test.logging.slf4j.logback.TestAppender">
+    <appender name="testAppender" class="org.springframework.data.gemfire.tests.logging.slf4j.logback.TestAppender">
         <encoder>
             <pattern>TEST - %m%n</pattern>
         </encoder>
@@ -21,14 +21,10 @@
 
     <logger name="org.springframework" level="${logback.log.level:-ERROR}"/>
 
-    <logger name="org.springframework.data.gemfire.config.annotation.support.RegionDataAccessTracingAspect" level="trace" additivity="false">
+    <logger name="org.springframework.data.gemfire.tests.logging.slf4j.logback.TestAppenderUnitTests" level="WARN">
         <appender-ref ref="testAppender"/>
     </logger>
 
-    <logger name="org.springframework.data.gemfire.listener.adapter.ContinuousQueryListenerAdapter" level="off" additivity="false"/>
-
-    <logger name="org.springframework.data.gemfire.support.SpringContextBootstrappingInitializer" level="off" additivity="false"/>
-
     <root level="${logback.log.level:-ERROR}">
         <appender-ref ref="console"/>
     </root>