Add CompositeAppender Logback Appender implementation to compose multiple Appenders as a single Appender.

Resolve gh-73.

spring-geode-starter-logging/src/test/java/org/springframework/geode/logging/slf4j/logback/CompositeAppenderUnitTests.java

@@ -0,0 +1,158 @@
+/*
+ * 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.geode.logging.slf4j.logback;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+
+import ch.qos.logback.core.Appender;
+import ch.qos.logback.core.Context;
+
+/**
+ * Unit Tests for {@link CompositeAppender}.
+ *
+ * @author John Blum
+ * @see org.junit.Test
+ * @see org.mockito.Mock
+ * @see org.mockito.Mockito
+ * @see org.mockito.junit.MockitoJUnitRunner
+ * @see org.springframework.geode.logging.slf4j.logback.CompositeAppender
+ * @see ch.qos.logback.core.Appender
+ * @since 1.3.0
+ */
+@RunWith(MockitoJUnitRunner.class)
+@SuppressWarnings({ "rawtypes", "unchecked" })
+public class CompositeAppenderUnitTests {
+
+	@Mock
+	private Appender mockAppenderOne;
+
+	@Mock
+	private Appender mockAppenderTwo;
+
+	@Test
+	public void composeIsNullSafe() {
+		assertThat(CompositeAppender.compose(null, null)).isNull();
+	}
+
+	@Test
+	public void composeSingleAppenderReturnsTheAppender() {
+
+		assertThat(CompositeAppender.compose(this.mockAppenderOne, null)).isEqualTo(this.mockAppenderOne);
+		assertThat(CompositeAppender.compose(null, this.mockAppenderTwo)).isEqualTo(this.mockAppenderTwo);
+	}
+
+	@Test
+	public void composeTwoAppendersReturnsCompositeAppender() {
+
+		Appender<?> composite = CompositeAppender.compose(this.mockAppenderOne, this.mockAppenderTwo);
+
+		assertThat(composite).isInstanceOf(CompositeAppender.class);
+		assertThat((((CompositeAppender<?>) composite).getAppenderOne())).isEqualTo(this.mockAppenderOne);
+		assertThat((((CompositeAppender<?>) composite).getAppenderTwo())).isEqualTo(this.mockAppenderTwo);
+		assertThat(composite.getName()).isEqualTo(CompositeAppender.DEFAULT_NAME);
+		assertThat(composite.isStarted()).isTrue();
+	}
+
+	@Test
+	public void setContextConfiguresContextOnCompositeAppenderAndComposedAppenders() {
+
+		Context mockContext = mock(Context.class);
+
+		Appender compositeAppender = CompositeAppender.compose(this.mockAppenderOne, this.mockAppenderTwo);
+
+		assertThat(compositeAppender).isInstanceOf(CompositeAppender.class);
+
+		compositeAppender.setContext(mockContext);
+
+		assertThat(compositeAppender.getContext()).isEqualTo(mockContext);
+
+		verify(this.mockAppenderOne, times(1)).setContext(eq(mockContext));
+		verify(this.mockAppenderTwo, times(1)).setContext(eq(mockContext));
+	}
+
+	@Test
+	public void getContextReturnsConfiguredContext() {
+
+		Context mockContext = mock(Context.class);
+
+		Appender compositeAppender = CompositeAppender.compose(this.mockAppenderOne, this.mockAppenderTwo);
+
+		assertThat(compositeAppender).isInstanceOf(CompositeAppender.class);
+
+		compositeAppender.setContext(mockContext);
+
+		assertThat(compositeAppender.getContext()).isEqualTo(mockContext);
+
+		verify(this.mockAppenderOne, never()).getContext();
+		verify(this.mockAppenderTwo, never()).getContext();
+	}
+
+	@Test
+	public void getContextReturnsAppenderOneContext() {
+
+		Context mockContext = mock(Context.class);
+
+		doReturn(mockContext).when(this.mockAppenderOne).getContext();
+
+		Appender compositeAppender = CompositeAppender.compose(this.mockAppenderOne, this.mockAppenderTwo);
+
+		assertThat(compositeAppender).isInstanceOf(CompositeAppender.class);
+		assertThat(compositeAppender.getContext()).isEqualTo(mockContext);
+
+		verify(this.mockAppenderOne, times(1)).getContext();
+		verify(this.mockAppenderTwo, never()).getContext();
+	}
+
+	@Test
+	public void getContextReturnsAppenderTwoContext() {
+
+		Context mockContext = mock(Context.class);
+
+		doReturn(mockContext).when(this.mockAppenderTwo).getContext();
+
+		Appender compositeAppender = CompositeAppender.compose(this.mockAppenderOne, this.mockAppenderTwo);
+
+		assertThat(compositeAppender).isInstanceOf(CompositeAppender.class);
+		assertThat(compositeAppender.getContext()).isEqualTo(mockContext);
+
+		verify(this.mockAppenderOne, times(1)).getContext();
+		verify(this.mockAppenderTwo, times(1)).getContext();
+	}
+
+	@Test
+	public void appendCallsAppenderOneAppendAndAppenderTwoAppend() {
+
+		Appender compositeAppender = CompositeAppender.compose(this.mockAppenderOne, this.mockAppenderTwo);
+
+		assertThat(compositeAppender).isInstanceOf(CompositeAppender.class);
+
+		((CompositeAppender<Object>) compositeAppender).append("TEST");
+
+		verify(this.mockAppenderOne, times(1)).doAppend(eq("TEST"));
+		verify(this.mockAppenderTwo, times(1)).doAppend(eq("TEST"));
+	}
+}