fix issue #34 : make method "beforeEvaluate" return a boolean

easyrules-core/src/main/java/org/easyrules/api/RuleListener.java

@@ -10,9 +10,10 @@ public interface RuleListener {
     /**
      * Triggered before the evaluation of a rule.
      *
-     * @param rule the current rule
+     * @param rule being evaluated
+     * @return true if the rule should be evaluated, false otherwise
      */
-    Rule beforeEvaluate(Rule rule);
+    boolean beforeEvaluate(Rule rule);
 
     /**
      * Triggered before the execution of a rule.

easyrules-core/src/main/java/org/easyrules/core/DefaultRulesEngine.java

@@ -149,8 +149,7 @@ class DefaultRulesEngine implements RulesEngine {
                 break;
             }
 
-            rule = triggerListenersBeforeEvaluate(rule);
-            if (rule == null) {
+            if (!triggerListenersBeforeEvaluate(rule)) {
                 LOGGER.log(Level.INFO, "Rule ''{0}'' has been skipped before being evaluated", name);
                 continue;
             }
@@ -200,11 +199,13 @@ class DefaultRulesEngine implements RulesEngine {
         }
     }
 
-    private Rule triggerListenersBeforeEvaluate(Rule rule) {
+    private boolean triggerListenersBeforeEvaluate(Rule rule) {
         for (RuleListener ruleListener : ruleListeners) {
-            rule = ruleListener.beforeEvaluate(rule);
+            if (!ruleListener.beforeEvaluate(rule)) {
+                return false;
             }
-        return rule;
+        }
+        return true;
     }
 
     private void logEngineParameters() {

easyrules-core/src/test/java/org/easyrules/core/RuleListenerTest.java

@@ -57,8 +57,8 @@ public class RuleListenerTest {
         when(rule.getName()).thenReturn("r");
         when(rule.getPriority()).thenReturn(1);
         when(rule.evaluate()).thenReturn(true);
-        when(ruleListener1.beforeEvaluate(rule)).thenReturn(rule);
-        when(ruleListener2.beforeEvaluate(rule)).thenReturn(rule);
+        when(ruleListener1.beforeEvaluate(rule)).thenReturn(true);
+        when(ruleListener2.beforeEvaluate(rule)).thenReturn(true);
 
         rulesEngine = aNewRulesEngine()
                 .withRuleListener(ruleListener1)
@@ -100,10 +100,10 @@ public class RuleListenerTest {
     }
 
     @Test
-    public void whenListenerReturnsNull_thenTheRuleShouldBeSkippedBeforeBeingEvaluated() throws Exception {
+    public void whenListenerReturnsFalse_thenTheRuleShouldBeSkippedBeforeBeingEvaluated() throws Exception {
 
         // Given
-        when(ruleListener1.beforeEvaluate(rule)).thenReturn(null);
+        when(ruleListener1.beforeEvaluate(rule)).thenReturn(false);
         rulesEngine = aNewRulesEngine()
                 .withRuleListener(ruleListener1)
                 .build();
@@ -113,8 +113,24 @@ public class RuleListenerTest {
         rulesEngine.fireRules();
 
         // Then
-        verify(rule, never()).execute();
+        verify(rule, never()).evaluate();
+    }
+
+    @Test
+    public void whenListenerReturnsTrue_thenTheRuleShouldBeEvaluated() throws Exception {
 
+        // Given
+        when(ruleListener1.beforeEvaluate(rule)).thenReturn(true);
+        rulesEngine = aNewRulesEngine()
+                .withRuleListener(ruleListener1)
+                .build();
+
+        // When
+        rulesEngine.registerRule(rule);
+        rulesEngine.fireRules();
+
+        // Then
+        verify(rule).evaluate();
     }
 
 }