Change silly edge case behaviour

basics_input.txt

@@ -19,7 +19,7 @@ add train 1 T1-Alpha
 add train 2 T1-Beta
 put train 1 at (0,5) in direction 0,1
 put train 2 at (0,0) in direction 1,0
-step 1
+step 6
 put train 1 at (0,0) in direction 0,-1
 set switch 3 position (0,0)
 put train 1 at (0,0) in direction 0,-1

basics_output.txt

@@ -23,7 +23,8 @@ steam engine T1-Alpha added to train 1
 electrical engine T1-Beta added to train 2
 OK
 OK
-Crash of train 1,2
+Crash of train 1
+Crash of train 2
 OK
 OK
 OK

src/edu/kit/informatik/MainTest.java

@@ -93,6 +93,11 @@ class MainTest {
         cmpInOut("testcoverage_input.txt", "testcoverage_output.txt");
     }
 
+    @Test
+    void oneLengthDerailEdgecase() throws IOException {
+        cmpInOut("train_one_length_input.txt", "train_one_length_output.txt");
+    }
+
     private void cmpInOut(String in, String out) throws IOException {
         System.setIn(new ByteArrayInputStream(readFile(in)));
         ByteArrayOutputStream output = new ByteArrayOutputStream();

src/edu/kit/informatik/model/TrainManager.java

@@ -236,7 +236,12 @@ public final class TrainManager {
                     || train.isOnPosition(nextPosition) && !train.getRearPosition().equals(train.getFrontPosition())) {
                 collisions.add(new HashSet<>(Arrays.asList(train)));
                 train.removeFromRails();
-                nextOccupiedRails.put(train, occupiedRails.get(train));
+                // see https://ilias.studium.kit.edu/goto.php?target=frm_996924_138875&client_id=produktiv
+                if (train.getLength() > 1) {
+                    nextOccupiedRails.put(train, occupiedRails.get(train));
+                } else {
+                    nextOccupiedRails.put(train, null);
+                }
             } else {
                 train.moveTo(railNetwork, nextPosition);
                 train.setDirection(direction);
@@ -266,7 +271,12 @@ public final class TrainManager {
                     || train.isOnPosition(nextPosition) && !train.getRearPosition().equals(train.getFrontPosition())) {
                 collisions.add(new HashSet<>(Arrays.asList(train)));
                 train.removeFromRails();
-                nextOccupiedRails.put(train, occupiedRails.get(train));
+                // see https://ilias.studium.kit.edu/goto.php?target=frm_996924_138875&client_id=produktiv
+                if (train.getLength() > 1) {
+                    nextOccupiedRails.put(train, occupiedRails.get(train));
+                } else {
+                    nextOccupiedRails.put(train, null);
+                }
             } else {
                 train.moveBackTo(railNetwork, nextPosition);
                 train.setDirection(front.subtract(train.getFrontPosition()));
@@ -297,7 +307,7 @@ public final class TrainManager {
                     trains.values().stream().filter(x -> x != train).forEach(otherTrain -> {
                         Set<Rail> occupiedByOtherTrainPreviously = occupiedRails.get(otherTrain);
                         Set<Rail> occupiedByOtherTrain = nextOccupiedRails.get(otherTrain);
-                        // if train did not occupy any rails (it is not placed)
+                        // if train did not occupy any rails (it is not placed, or just derailed with length 1)
                         if (occupiedByOtherTrain == null) {
                             // skip
                             return;

train_one_length_input.txt

@@ -0,0 +1,13 @@
+add track (0,0) -> (5,0)
+add track (5,0) -> (10,0)
+create engine diesel T6 Lux 1 true true
+create engine diesel T6 Lumen 2 false false
+add train 1 T6-Lux
+add train 2 T6-Lumen
+put train 2 at (10,0) in direction 1,0
+put train 1 at (5,0) in direction 1,0
+step 1
+put train 2 at (5,0) in direction 1,0
+put train 1 at (10,0) in direction 1,0
+step 1
+exit

train_one_length_output.txt

@@ -0,0 +1,13 @@
+1
+2
+T6-Lux
+T6-Lumen
+diesel engine T6-Lux added to train 1
+diesel engine T6-Lumen added to train 2
+OK
+OK
+Crash of train 1,2
+OK
+OK
+Crash of train 1
+Train 2 at (6,0)