[SHRINKDESC-60] added removeAttribute method to Node, including testcase

spi/src/main/java/org/jboss/shrinkwrap/descriptor/spi/Node.java

@@ -173,6 +173,23 @@ public String getAttribute(final String name)
       return this.attributes.get(name);
    }
 
+   /**
+    * Remove a named attribute.<br/>
+    *
+    * @param name The attribute name
+    * @return The attribute value that was removed, or null if the attribute with the given name was not found.
+    * @throws IllegalArgumentException if the attribute with the given name does not exist on the node
+    */
+   public String removeAttribute(final String name) throws IllegalArgumentException
+   {
+      String remove = this.attributes.remove(name);
+      if (remove == null)
+      {
+         throw new IllegalArgumentException("attribute with name '" + name + "' does not exist");
+      }
+      return remove;
+   }
+
    /**
     * Get all defined attributes for this Node in an 
     * immutable view

spi/src/test/java/org/jboss/shrinkwrap/descriptor/spi/NodeTestCase.java

@@ -458,4 +458,31 @@ public void shouldBeAbleToReportAsRoot()
       Assert.assertFalse("Child should not report as root", child.isRoot());
    }
 
+   @Test
+   public void shouldRemoveAttributeByName() throws Exception
+   {
+      Node root = new Node(ROOT_NAME).attribute(ATTR_NAME, ATTR_VALUE);
+      Assert.assertEquals("attribute should exist", root.getAttribute(ATTR_NAME), ATTR_VALUE);
+
+      Assert.assertEquals("attribute value should be returned on removal", root.removeAttribute(ATTR_NAME), ATTR_VALUE);
+      Assert.assertNull("attribute should no longer exist", root.getAttribute(ATTR_NAME));
+   }
+
+   @Test
+   public void shouldThrowExceptionWhenAttemptingToRemoveAttributeThatDoesNotExist() throws Exception
+   {
+      String bogusAttribute = "SOME_NONEXISTANT_ATTR";
+
+      Node root = new Node(ROOT_NAME).attribute(ATTR_NAME, ATTR_VALUE);
+      Assert.assertEquals("attribute should exist", root.getAttribute(ATTR_NAME), ATTR_VALUE);
+
+      try
+      {
+         root.removeAttribute(bogusAttribute);
+         Assert.fail("should have thrown " + IllegalArgumentException.class.getSimpleName());
+      } catch (IllegalArgumentException e)
+      {
+         Assert.assertTrue("message should contain the attribute name", e.getMessage().contains(bogusAttribute));
+      }
+   }
 }