Increase test coverage for ProxyNode

Author: ftomassetti

core/src/test/java/io/lionweb/model/impl/ProxyNodeTest.java

@@ -1,7 +1,6 @@
 package io.lionweb.model.impl;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertThrows;
+import static org.junit.Assert.*;
 
 import io.lionweb.language.*;
 import org.junit.Test;
@@ -18,13 +17,39 @@ public void operationsCannotBePerformed() {
     ProxyNode proxyNode = new ProxyNode("id-123");
 
     Property p = new Property();
+    Containment c = new Containment();
+    ProxyNode anotherProxyNode = new ProxyNode("id-124");
 
     assertThrows(ProxyNode.CannotDoBecauseProxyException.class, proxyNode::getAnnotations);
     assertThrows(ProxyNode.CannotDoBecauseProxyException.class, proxyNode::getClassifier);
     assertThrows(ProxyNode.CannotDoBecauseProxyException.class, proxyNode::getParent);
+    assertThrows(ProxyNode.CannotDoBecauseProxyException.class, proxyNode::getContainmentFeature);
     assertThrows(
         ProxyNode.CannotDoBecauseProxyException.class, () -> proxyNode.getPropertyValue(p));
     assertThrows(
         ProxyNode.CannotDoBecauseProxyException.class, () -> proxyNode.setPropertyValue(p, "foo"));
+    assertThrows(ProxyNode.CannotDoBecauseProxyException.class, () -> proxyNode.getChildren(c));
+    assertThrows(
+        ProxyNode.CannotDoBecauseProxyException.class,
+        () -> proxyNode.addChild(c, anotherProxyNode));
+    assertThrows(
+        ProxyNode.CannotDoBecauseProxyException.class,
+        () -> proxyNode.removeChild(anotherProxyNode));
+    assertThrows(ProxyNode.CannotDoBecauseProxyException.class, () -> proxyNode.removeChild(c, 0));
+  }
+
+  @Test
+  public void auxiliaryMethods() {
+    ProxyNode proxyNode1 = new ProxyNode("id-123");
+    ProxyNode proxyNode2 = new ProxyNode("id-123");
+    ProxyNode proxyNode3 = new ProxyNode("id-124");
+
+    assertEquals(proxyNode1, proxyNode2);
+    assertNotEquals(proxyNode1, proxyNode3);
+
+    assertEquals(proxyNode1.hashCode(), proxyNode2.hashCode());
+    assertNotEquals(proxyNode1.hashCode(), proxyNode3.hashCode());
+
+    assertEquals("ProxyNode(id-123)", proxyNode1.toString());
   }
 }