Add some fail tests for validators

Author: patrickfav

src/main/java/at/favre/lib/bytes/BytesValidator.java

@@ -147,12 +147,12 @@ enum Operator {
         private final Operator operator;
 
         public Logical(List<BytesValidator> validatorList, Operator operator) {
-            if (validatorList.isEmpty()) throw new IllegalArgumentException("must contain at least 1 element");
+            if (validatorList.isEmpty())
+                throw new IllegalArgumentException("must contain at least 1 element");
             if (operator == NOT && validatorList.size() != 1)
                 throw new IllegalArgumentException("not operator can only be applied to single element");
             this.validatorList = validatorList;
             this.operator = operator;
-
         }
 
         @Override

src/test/java/at/favre/lib/bytes/BytesValidatorTest.java

@@ -23,6 +23,9 @@
 
 import org.junit.Test;
 
+import java.util.Arrays;
+import java.util.Collections;
+
 import static at.favre.lib.bytes.BytesValidators.*;
 import static org.junit.Assert.*;
 
@@ -85,6 +88,18 @@ public void testNotValidation() throws Exception {
         assertFalse(Bytes.allocate(2).validate(not(atMost(16))));
     }
 
+    @Test(expected = IllegalArgumentException.class)
+    public void testLogicalNoElements() throws Exception {
+        Bytes.allocate(2).validate(new BytesValidator.Logical(Collections.<BytesValidator>emptyList(), BytesValidator.Logical.Operator.AND));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testLogicalTooManyElements() throws Exception {
+        Bytes.allocate(2).validate(new BytesValidator.Logical(
+                Arrays.<BytesValidator>asList(new BytesValidator.Length(2, BytesValidator.Length.Mode.GREATER_OR_EQ_THAN), new BytesValidator.Length(2, BytesValidator.Length.Mode.EXACT))
+                , BytesValidator.Logical.Operator.NOT));
+    }
+
     @Test
     public void testNestedValidation() throws Exception {
         assertTrue(Bytes.allocate(16).validate(