add getAbove() in Matchfield - Case: nothingBelow

src/main/java/de/tims/fleetstorm/matchfield/Matchfield.java

@@ -48,7 +48,9 @@ public class Matchfield {
 	}
 
 	public Coordinate getBelow(Coordinate center) {
-		// TODO Auto-generated method stub
+		if (center.getX() == 0) {
+			return null;
+		}
 		return this.matchfield[center.getX() - 1][center.getY()];
 	}
 

src/test/java/de/tims/fleetstorm/matchfield/MatchfieldCreationTest.java

@@ -90,7 +90,9 @@ class MatchfieldCreationTest {
 
 	static Stream<Arguments> getCoordinateBelow() {
 		Matchfield matchfield = new Matchfield(10);
-		return Stream.of(Arguments.of("bewlow from (5/5) - should be (4,5)", matchfield, new Coordinate(5, 5),
-				matchfield.getField(4, 5)));
+		return Stream.of(
+				Arguments.of("bewlow from (5/5) - should be (4,5)", matchfield, new Coordinate(5, 5),
+						matchfield.getField(4, 5)),
+				Arguments.of("bewlow from (0/5) - should be null", matchfield, new Coordinate(0, 5), null));
 	}
 }