Implemented test if ship is already on position in shipSet

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

@@ -79,7 +79,12 @@ public class Matchfield {
 	public boolean setShip(Coordinate coordinate, int length, int direction) {
 
 		for (int i = 0; i < length; i++) {
-			this.getField(coordinate).setState(Coordinate.SHIP);
+
+			Coordinate field = this.getField(coordinate);
+			if (field.getState() == Coordinate.SHIP)
+				return false;
+
+			field.setState(Coordinate.SHIP);
 			if (direction == 0)
 				coordinate = this.getRight(coordinate);
 			if (direction == 1)

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

@@ -6,6 +6,7 @@ import static org.junit.Assert.assertTrue;
 
 import java.util.stream.Stream;
 
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
@@ -69,4 +70,16 @@ class MatchfieldPositioningTest {
 				Arguments.of("valid ship position from 8:0, length 5, direction 1", 10, new Coordinate(9, 0), 1, 5,
 						true));
 	}
+
+	@Test
+	void testShipPositionAlreadySetWithShip() {
+		Matchfield matchfield = new Matchfield(10);
+		matchfield.createMatchfield();
+
+		matchfield.setShip(new Coordinate(0, 0), 5, 1);
+		assertFalse(matchfield.setShip(new Coordinate(0, 1), 5, 1));
+
+		assertTrue(matchfield.setShip(new Coordinate(1, 1), 4, 0));
+		assertFalse(matchfield.setShip(new Coordinate(4, 1), 2, 1));
+	}
 }