Added some more JUnit tests

src/main/java/kieker/diagnosis/common/Mapper.java

@@ -22,13 +22,18 @@ import java.util.Map;
 public final class Mapper<I, O> {
 
 	private final Map<I, O> internalMap = new HashMap<>();
+	public O defaultValue;
 
 	public To map(final I key) {
 		return new To(key);
 	}
 
+	public To mapPerDefault() {
+		return new To();
+	}
+
 	public O resolve(final I key) {
-		return this.internalMap.get(key);
+		return this.internalMap.getOrDefault(key, this.defaultValue);
 	}
 
 	public I invertedResolve(final O value) {
@@ -43,13 +48,24 @@ public final class Mapper<I, O> {
 	public final class To {
 
 		private final I key;
+		private final boolean keyAvailable;
 
 		To(final I key) {
 			this.key = key;
+			this.keyAvailable = true;
+		}
+
+		public To() {
+			this.key = null;
+			this.keyAvailable = false;
 		}
 
 		public void to(final O value) { // NOPMD (the method name may be short, but this is acceptable in this case)
-			Mapper.this.internalMap.put(this.key, value);
+			if (this.keyAvailable) {
+				Mapper.this.internalMap.put(this.key, value);
+			} else {
+				Mapper.this.defaultValue = value;
+			}
 		}
 
 	}

src/main/java/kieker/diagnosis/subview/util/NameConverter.java

@@ -38,6 +38,7 @@ public final class NameConverter {
 		NameConverter.shortTimeUnitMapper.map(TimeUnit.MINUTES).to("m");
 		NameConverter.shortTimeUnitMapper.map(TimeUnit.HOURS).to("h");
 		NameConverter.shortTimeUnitMapper.map(TimeUnit.DAYS).to("d");
+		NameConverter.shortTimeUnitMapper.mapPerDefault().to("");
 	}
 
 	public static String toShortTimeUnit(final TimeUnit timeUnit) {

src/test/java/kieker/diagnosis/common/MapperTest.java

@@ -19,7 +19,6 @@ package kieker.diagnosis.common;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.core.IsNull.nullValue;
 import static org.junit.Assert.assertThat;
-import kieker.diagnosis.common.Mapper;
 
 import org.junit.Test;
 
@@ -71,4 +70,25 @@ public class MapperTest {
 		assertThat(mapper.invertedResolve("One"), is(1));
 	}
 
+	@Test
+	public void defaultMappingShouldWork() {
+		final Mapper<Integer, String> mapper = new Mapper<>();
+
+		mapper.mapPerDefault().to("N/A");
+		mapper.map(1).to("One");
+
+		assertThat(mapper.resolve(1), is("One"));
+		assertThat(mapper.resolve(2), is("N/A"));
+	}
+
+	@Test
+	public void defaultMappingDoesNotConflictWithNullMapping() {
+		final Mapper<Integer, String> mapper = new Mapper<>();
+
+		mapper.mapPerDefault().to("N/A");
+		mapper.map(null).to("Zero");
+
+		assertThat(mapper.resolve(null), is("Zero"));
+	}
+
 }

src/test/java/kieker/diagnosis/subview/util/NameConverterTest.java

@@ -19,6 +19,8 @@ package kieker.diagnosis.subview.util;
 import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.assertThat;
 
+import java.util.concurrent.TimeUnit;
+
 import org.junit.Test;
 
 public class NameConverterTest {
@@ -51,4 +53,60 @@ public class NameConverterTest {
 		assertThat(result, is("getBook(...)"));
 	}
 
+	@Test
+	public void toShortTimeUnitForNanosecondsShouldWork() {
+		final String result = NameConverter.toShortTimeUnit(TimeUnit.NANOSECONDS);
+
+		assertThat(result, is("ns"));
+	}
+
+	@Test
+	public void toShortTimeUnitForMicrosecondsShouldWork() {
+		final String result = NameConverter.toShortTimeUnit(TimeUnit.MICROSECONDS);
+
+		assertThat(result, is("us"));
+	}
+
+	@Test
+	public void toShortTimeUnitForMillisecondsShouldWork() {
+		final String result = NameConverter.toShortTimeUnit(TimeUnit.MILLISECONDS);
+
+		assertThat(result, is("ms"));
+	}
+
+	@Test
+	public void toShortTimeUnitForSecondsShouldWork() {
+		final String result = NameConverter.toShortTimeUnit(TimeUnit.SECONDS);
+
+		assertThat(result, is("s"));
+	}
+
+	@Test
+	public void toShortTimeUnitForMinutesShouldWork() {
+		final String result = NameConverter.toShortTimeUnit(TimeUnit.MINUTES);
+
+		assertThat(result, is("m"));
+	}
+
+	@Test
+	public void toShortTimeUnitForHoursShouldWork() {
+		final String result = NameConverter.toShortTimeUnit(TimeUnit.HOURS);
+
+		assertThat(result, is("h"));
+	}
+
+	@Test
+	public void toShortTimeUnitForDaysShouldWork() {
+		final String result = NameConverter.toShortTimeUnit(TimeUnit.DAYS);
+
+		assertThat(result, is("d"));
+	}
+
+	@Test
+	public void toShortTimeUnitForNullShouldReturnEmptyString() {
+		final String result = NameConverter.toShortTimeUnit(null);
+
+		assertThat(result, is(""));
+	}
+
 }