Fixed testing problem where race tests would sometimes fail because a boat did not finish

- Added an option to set the dnf chance, then set it to 0 is all tests

#story[760]

src/main/java/seng302/Model/Race.java

@@ -24,6 +24,7 @@ public abstract class Race implements Runnable {
     protected RaceController controller;
     protected int boatsFinished = 0;
     protected long totalTimeElapsed;
+    private int dnfChance = 1; //%percentage chance a boat fails at each checkpoint
 
     private int lastFPS = 20;
 
@@ -54,6 +55,16 @@ public abstract class Race implements Runnable {
         }
     }
 
+    /**
+     * Sets the chance each boat has of failing at a gate or marker
+     * @param chance percentage chance a boat has of failing per checkpoint.
+     */
+    protected void setDnfChance(int chance) {
+        if (chance >= 0 && chance <= 100) {
+            dnfChance = chance;
+        }
+    }
+
 
     public void initialiseBoats() {
 
@@ -174,7 +185,7 @@ public abstract class Race implements Runnable {
 
     private boolean doNotFinish() {
         Random rand = new Random();
-        return rand.nextInt(4) < 1;
+        return rand.nextInt(100) < dnfChance;
     }
 
     /**