add CapturingAppenderUnitTest

src/test/java/de/dm/infrastructure/logcapture/CapturingAppenderUnitTest.java

@@ -0,0 +1,49 @@
+package de.dm.infrastructure.logcapture;
+
+import ch.qos.logback.classic.LoggerContext;
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.core.filter.Filter;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mock;
+
+import java.util.Set;
+
+import static ch.qos.logback.core.spi.FilterReply.ACCEPT;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+
+class CapturingAppenderUnitTest {
+
+    @Mock
+    LoggerContext loggerContext;
+
+    CapturingAppender sut = new CapturingAppender(loggerContext, Set.of(
+            "a.package",
+            "another.package")
+    );
+
+    @SuppressWarnings("unchecked") // filter types are irrelevant
+    @Test
+    void neverFiltersAndNeverHasAnyFilters() {
+        assertThat(sut.getFilterChainDecision(mock(ILoggingEvent.class))).isEqualTo(ACCEPT);
+
+        sut.addFilter(mock(Filter.class));
+
+        assertThat(sut.getFilterChainDecision(mock(ILoggingEvent.class))).isEqualTo(ACCEPT);
+        assertThat(sut.getCopyOfAttachedFiltersList()).isEmpty();
+
+        sut.clearAllFilters();
+
+        assertThat(sut.getFilterChainDecision(mock(ILoggingEvent.class))).isEqualTo(ACCEPT);
+    }
+
+    @Test
+    void startStop() {
+        assertThat(sut.isStarted()).isFalse();
+        sut.start();
+        assertThat(sut.isStarted()).isTrue();
+        sut.stop();
+        assertThat(sut.isStarted()).isFalse();
+    }
+
+}