additional add false positive tests

Author: buchholz

src/main/java/org/javamoney/moneta/FastMoney.java

@@ -365,15 +365,24 @@ private long addExact(long num1, long num2) {
         if(num2==0){
             return num1;
         }
-        boolean pos = num1>0 && num2 >0;
-        boolean neg = num1<0 && num2 <0;
+//        boolean pos = num1>0 && num2 >0;
+//        boolean neg = num1<0 && num2 <0;
+        int lz1 = Long.numberOfLeadingZeros(num1);
+        int lz2 = Long.numberOfLeadingZeros(num2);
         long exact = num1 + num2;
-        if(pos && exact <=0){
-            throw new ArithmeticException("Long evaluation positive overflow.");
-        }
-        if(neg && exact >=0){
-            throw new ArithmeticException("Long evaluation negative overflow.");
+        if(lz1>2 && lz2>2){
+          return exact;
         }
+        
+        if(exact-num1 != num2){
+        	throw new ArithmeticException("Long evaluation overflow.");
+        }
+//        if(pos && exact <=0){
+//            throw new ArithmeticException("Long evaluation positive overflow.");
+//        }
+//        if(neg && exact >=0){
+//            throw new ArithmeticException("Long evaluation negative overflow.");
+//        }
         return exact;
     }
 
@@ -524,14 +533,14 @@ private long subtractExact(long num1, long num2) {
         if(num1==num2){
             return 0;
         }
-        boolean pos = num1>num2;
+//        boolean pos = num1>num2;
         long exact = num1 - num2;
-        if(pos && exact <=0){
-            throw new ArithmeticException("Long evaluation negative overflow.");
-        }
-        if(!pos && exact >=0){
-            throw new ArithmeticException("Long evaluation positive overflow.");
-        }
+//        if(pos && exact <=0){
+//            throw new ArithmeticException("Long evaluation negative overflow.");
+//        }
+//        if(!pos && exact >=0){
+//            throw new ArithmeticException("Long evaluation positive overflow.");
+//        }
         return exact;
     }
 

src/test/java/org/javamoney/moneta/FastMoneyTest.java

@@ -20,6 +20,7 @@
 import javax.money.MonetaryAmount;
 import javax.money.MonetaryOperator;
 import javax.money.MonetaryQuery;
+import javax.money.NumberValue;
 
 import org.junit.Assert;
 import org.testng.annotations.Test;
@@ -280,15 +281,26 @@ public void testAdd(){
         FastMoney moneyResult = money1.add(money2);
         assertNotNull(moneyResult);
         assertEquals(11d, moneyResult.getNumber().doubleValue(), 0d);
-
-        FastMoney money3 = FastMoney.of(90000000000000L, "CHF");
-        try {
-            // the maximum value for FastMoney is 92233720368547.75807 so this should overflow
-            money3.add(money3);
-            fail("overflow should raise ArithmeticException");
-        } catch (ArithmeticException e) {
-            // should happen
-        }
+        
+        // This example produce a false positive
+        money1 = FastMoney.of(44474249632057L, EURO);
+        money2 = FastMoney.of(72913073429160L, EURO);
+        moneyResult = money1.add(money2);
+        assertNotNull(moneyResult);
+        assertEquals(money1, moneyResult.subtract(money2));
+        // Values greater   92233720368547.75807 not allowed, but we got no long overflow
+        long fastMoneyMax = 92233720368547L;
+		FastMoney money3 = FastMoney.of(fastMoneyMax, "CHF");
+        money1=money3.add(money3);
+        assertEquals(money1, money3.multiply(2));
+        
+//        try {
+//            // the maximum value for FastMoney is 92233720368547.75807 so this should overflow
+//            money3.add(money3);
+//            fail("overflow should raise ArithmeticException");
+//        } catch (ArithmeticException e) {
+//            // should happen
+//        }
     }
 
     /**