Node.getName(): generated each time called when using a name supplier

Previously the name was set when the node was created and only a call to
setName() would have changed it.

isNamed() uses the generated name, so this may change if the generated name
is even null or the empty string.

src/main/java/net/kemitix/node/Node.java

@@ -14,7 +14,8 @@ import java.util.Set;
 public interface Node<T> {
 
     /**
-     * Fetch the name of the node.
+     * Fetch the name of the node. Where a node's name is determined via a name
+     * supplier, the name may be regenerated each time this method is called.
      *
      * @return the name of the node
      */
@@ -193,7 +194,8 @@ public interface Node<T> {
     String drawTree(int depth);
 
     /**
-     * Returns true if the Node has a name.
+     * Returns true if the Node has a name. Where a name supplier is used, the
+     * generated name is used.
      *
      * @return true if the node has a name
      */

src/main/java/net/kemitix/node/NodeItem.java

@@ -57,7 +57,6 @@ public class NodeItem<T> implements Node<T> {
             final T data, final Function<Node<T>, String> nameSupplier) {
         this(data);
         this.nameSupplier = nameSupplier;
-        name = generateName();
     }
 
     /**
@@ -69,7 +68,6 @@ public class NodeItem<T> implements Node<T> {
     public NodeItem(final T data, final Node<T> parent) {
         this.data = data;
         setParent(parent);
-        this.name = generateName();
     }
 
     /**
@@ -114,6 +112,9 @@ public class NodeItem<T> implements Node<T> {
 
     @Override
     public String getName() {
+        if (name == null) {
+            return generateName();
+        }
         return name;
     }
 
@@ -386,7 +387,8 @@ public class NodeItem<T> implements Node<T> {
 
     @Override
     public boolean isNamed() {
-        return name != null && name.length() > 0;
+        String currentName = getName();
+        return currentName != null && currentName.length() > 0;
     }
 
     @Override

src/test/java/net/kemitix/node/NodeItemTest.java

@@ -13,6 +13,7 @@ import java.time.format.DateTimeFormatter;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Optional;
+import java.util.concurrent.atomic.AtomicInteger;
 
 /**
  * Test for {@link NodeItem}.
@@ -973,4 +974,29 @@ public class NodeItemTest {
         //then
         assertThat(child.getName()).isEqualTo("local supplier");
     }
+
+    @Test
+    public void getNameWithNameSupplierIsRecalculatedEachCall() {
+        val counter = new AtomicInteger(0);
+        node = new NodeItem<>(null,
+                n -> Integer.toString(counter.incrementAndGet()));
+        //then
+        assertThat(node.getName()).isNotEqualTo(node.getName());
+    }
+
+    @Test
+    public void isNamedWithNameSupplierIsRecalculatedEachCall() {
+        val counter = new AtomicInteger(0);
+        node = new NodeItem<>(null, n -> {
+            // alternate between even numbers and nulls: null, 2, null, 4, null
+            final int i = counter.incrementAndGet();
+            if (i % 2 == 0) {
+                return Integer.toString(i);
+            }
+            return null;
+        });
+        //then
+        assertThat(node.isNamed()).isFalse();
+        assertThat(node.isNamed()).isTrue();
+    }
 }