Added a Unit Test to increase code coverage

src/test/java/com/google/escapevelocity/DirectiveNodeTest.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2022 Google, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.escapevelocity;
+
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+/**
+ * Unit tests for class {@link DirectiveNode}.
+ *
+ * @see DirectiveNode
+ *
+ */
+public class DirectiveNodeTest{
+
+  @Test
+  public void testRender() {
+      ConstantExpressionNode constantExpressionNode = new ConstantExpressionNode("", 2695, new Integer(2853));
+      try { 
+        new DirectiveNode.ForEachNode("", 2695, "", constantExpressionNode, new DirectiveNode.IfNode("", 0, constantExpressionNode, constantExpressionNode, constantExpressionNode)).render(null, new StringBuilder((CharSequence) ""));
+        fail("Expecting exception: EvaluationException");
+      } catch(EvaluationException e) {
+         assertEquals(Node.class.getName(), e.getStackTrace()[0].getClassName());
+      }
+  }
+
+}