handle IllegalArgumentException when fact type does not match parameter type

easy-rules-core/src/main/java/org/jeasy/rules/core/RuleProxy.java

@@ -23,11 +23,11 @@
  */
 package org.jeasy.rules.core;
 
-import org.jeasy.rules.annotation.Fact;
-import org.jeasy.rules.api.Facts;
 import org.jeasy.rules.annotation.Action;
 import org.jeasy.rules.annotation.Condition;
+import org.jeasy.rules.annotation.Fact;
 import org.jeasy.rules.annotation.Priority;
+import org.jeasy.rules.api.Facts;
 import org.jeasy.rules.api.Rule;
 
 import java.lang.annotation.Annotation;
@@ -36,6 +36,8 @@ import java.lang.reflect.Method;
 import java.lang.reflect.Proxy;
 import java.util.*;
 
+import static java.lang.String.format;
+
 /**
  * Main class to create rule proxies from annotated objects.
  *
@@ -87,7 +89,12 @@ public class RuleProxy implements InvocationHandler {
             Facts facts = (Facts) args[0];
             Method conditionMethod = getConditionMethod();
             List<Object> actualParameters = getActualParameters(conditionMethod, facts);
-            return conditionMethod.invoke(target, actualParameters.toArray()); // validated upfront
+            try {
+                return conditionMethod.invoke(target, actualParameters.toArray()); // validated upfront
+            } catch (IllegalArgumentException e) {
+                String error = "Types of injected facts in method '%s' in rule '%s' do not match parameters types";
+                throw new RuntimeException(format(error, conditionMethod.getName(), target.getClass().getName()), e);
+            }
         }
         if (methodName.equals("execute")) {
             for (ActionMethodOrderBean actionMethodBean : getActionMethodBeans()) {
@@ -121,19 +128,18 @@ public class RuleProxy implements InvocationHandler {
     private List<Object> getActualParameters(Method method, Facts facts) {
         List<Object> actualParameters = new ArrayList<>();
         Annotation[][] parameterAnnotations = method.getParameterAnnotations();
-        for(Annotation[] ann : parameterAnnotations){
-            if(ann.length == 1){
-                String factName = ((Fact) (ann[0])).value(); //validated upfront.
+        for (Annotation[] annotations : parameterAnnotations) {
+            if (annotations.length == 1) {
+                String factName = ((Fact) (annotations[0])).value(); //validated upfront.
                 Object fact = facts.get(factName);
-                if(fact == null){
-                    throw new RuntimeException(String.format("No fact named %s found in known facts", factName));
+                if (fact == null) {
+                    throw new RuntimeException(format("No fact named %s found in known facts", factName));
                 }
                 actualParameters.add(fact);
             } else {
                 actualParameters.add(facts); //validated upfront, there may be only one parameter not annotated and which is of type Facts.class
             }
         }
-
         return actualParameters;
     }
 

easy-rules-core/src/test/java/org/jeasy/rules/core/AnnotatedRulesTest.java

@@ -32,6 +32,8 @@ import org.jeasy.rules.api.Rules;
 import org.jeasy.rules.api.RulesEngine;
 import org.junit.Test;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 public class AnnotatedRulesTest {
 
     @Test
@@ -40,10 +42,23 @@ public class AnnotatedRulesTest {
         facts.add("rain", true);
         facts.add("age", 18);
 
-        Rules rules = new Rules(
-                new WeatherRule(),
-                new AgeRule()
-        );
+        WeatherRule weatherRule = new WeatherRule();
+        AgeRule ageRule = new AgeRule();
+        Rules rules = new Rules(weatherRule, ageRule);
+
+        RulesEngine rulesEngine = new DefaultRulesEngine();
+        rulesEngine.fire(rules, facts);
+
+        assertThat(ageRule.isExecuted()).isTrue();
+        assertThat(weatherRule.isExecuted()).isTrue();
+    }
+
+    @Test(expected = RuntimeException.class)
+    public void whenFactTypeDoesNotMatchParameterType_thenShouldThrowRuntimeException() throws Exception {
+        Facts facts = new Facts();
+        facts.add("age", "foo");
+
+        Rules rules = new Rules(new AgeRule());
 
         RulesEngine rulesEngine = new DefaultRulesEngine();
 
@@ -53,22 +68,30 @@ public class AnnotatedRulesTest {
     @Rule
     class AgeRule {
 
+        private boolean isExecuted;
+
         @Condition
         public boolean isAdult(@Fact("age") int age) {
             return age >= 18;
         }
 
         @Action
-        public void then() {
+        public void printYourAreAdult() {
             System.out.println("You are an adult");
+            isExecuted = true;
         }
 
+        public boolean isExecuted() {
+            return isExecuted;
+        }
     }
 
 
     @Rule
     class WeatherRule {
 
+        private boolean isExecuted;
+
         @Condition
         public boolean itRains(@Fact("rain") boolean rain) {
             return rain;
@@ -77,7 +100,11 @@ public class AnnotatedRulesTest {
         @Action
         public void takeAnUmbrella(Facts facts) {
             System.out.println("It rains, take an umbrella!");
+            isExecuted = true;
         }
 
+        public boolean isExecuted() {
+            return isExecuted;
+        }
     }
 }