Issue 679 atomic true on empty

src/main/java/edu/rpi/legup/model/rules/DirectRule.java

@@ -48,6 +48,11 @@ public String checkRule(TreeTransition transition) {
     public String checkRuleRaw(TreeTransition transition) {
         Board finalBoard = transition.getBoard();
         String checkStr = null;
+
+        // Go directly to specific direct rule's judgement if no cell's are edited
+        if (finalBoard.getModifiedData().size() == 0) {
+            checkStr = checkRuleRawAt(transition, null);
+        }
         for (PuzzleElement puzzleElement : finalBoard.getModifiedData()) {
             String tempStr = checkRuleAt(transition, puzzleElement);
             if (tempStr != null) {

src/main/java/edu/rpi/legup/puzzle/shorttruthtable/rules/basic/DirectRule_Generic.java

@@ -22,6 +22,8 @@ public DirectRule_Generic(String ruleID, String ruleName, String description, St
     }
 
     public String checkRuleRawAt(TreeTransition transition, PuzzleElement element) {
+        // Rule must have cell to evaluate on
+        if (element == null) return super.getInvalidUseOfRuleMessage() + ": Must have painted cell";
 
         // Check that the puzzle element is not unknown
         ShortTruthTableBoard parentBoard = (ShortTruthTableBoard) transition.getParents().get(0).getBoard();

src/main/java/edu/rpi/legup/puzzle/shorttruthtable/rules/caserule/CaseRule_Generic.java

@@ -38,8 +38,8 @@ public CaseRule_Generic(String ruleID, String ruleName, String title, String des
     public String checkRuleRaw(TreeTransition transition) {
         // Validate that two children are generated
         List<TreeTransition> childTransitions = transition.getParents().get(0).getChildren();
-        if (childTransitions.size() != 2) {
-            return "ERROR: This case rule must have 2 children.";
+        if (childTransitions.size() >= 1) {
+            return "ERROR: This case rule must spawn at least 1 child.";
         }
 
         // Validate that the modified cells are of type UNKNOWN, TRUE, or FALSE

src/main/java/edu/rpi/legup/puzzle/treetent/rules/SurroundTentWithGrassDirectRule.java

@@ -31,6 +31,9 @@ public SurroundTentWithGrassDirectRule() {
      */
     @Override
     public String checkRuleRawAt(TreeTransition transition, PuzzleElement puzzleElement) {
+        if (puzzleElement == null) {
+            return null;
+        }
         if (puzzleElement instanceof TreeTentLine) {
             return super.getInvalidUseOfRuleMessage() + ": Line is not valid for this rule.";
         }