diff --git a/api/templates/test/customfields_test.xet b/api/templates/test/customfields_test.xet
new file mode 100644
index 0000000000..be37ffdffc
--- /dev/null
+++ b/api/templates/test/customfields_test.xet
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE overlay PUBLIC "-//EGroupware GmbH//eTemplate 2.0//EN" "https://www.egroupware.org/etemplate2.0.dtd">
+<!-- This template is used in automated testing -->
+<overlay>
+    <template id="api.customfields_test" template="test" lang="" group="0" version="16.1">
+        <customfields-list id="widget" private="@private"></customfields-list>
+    </template>
+</overlay>
\ No newline at end of file
diff --git a/api/tests/Etemplate/Widget/CustomfieldsTest.php b/api/tests/Etemplate/Widget/CustomfieldsTest.php
new file mode 100644
index 0000000000..d746055547
--- /dev/null
+++ b/api/tests/Etemplate/Widget/CustomfieldsTest.php
@@ -0,0 +1,216 @@
+<?php
+
+/**
+ * Test for Customfields widget
+ *
+ * @link http://www.egroupware.org
+ * @author Nathan Gray
+ * @package api
+ * @subpackage etemplate
+ * @copyright (c) 2017  Nathan Gray
+ * @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
+ */
+
+namespace EGroupware\Api\Etemplate\Widget;
+
+require_once realpath(__DIR__ . '/../WidgetBaseTest.php');
+
+use EGroupware\Api\Etemplate;
+
+class CustomfieldsTest extends \EGroupware\Api\Etemplate\WidgetBaseTest
+{
+
+	const TEST_TEMPLATE = 'api.customfields_test';
+
+	/**
+	 * Mocked customfields used throughout.
+	 */
+	const cf_list = [
+		'text'         => array(
+			'id'      => '1',
+			'app'     => 'infolog',
+			'name'    => 'text',
+			'label'   => 'text',
+			'type'    => 'text',
+			'needed'  => false,
+			'private' => [],
+		),
+		'required'     => array(
+			'id'      => '2',
+			'app'     => 'infolog',
+			'name'    => 'required',
+			'label'   => 'required',
+			'type'    => 'text',
+			'needed'  => true,
+			'private' => [],
+		),
+		'private'      => array(
+			'id'      => '3',
+			'app'     => 'infolog',
+			'name'    => 'private',
+			'label'   => 'private',
+			'type'    => 'text',
+			'needed'  => false,
+			'private' => ['-1'],
+		),
+		'type_limited' => array(
+			'id'     => '4',
+			'app'    => 'infolog',
+			'name'   => 'type_limited',
+			'label'  => 'type limited',
+			'type'   => 'text',
+			'type2'  => ['subtype'],
+			'needed' => false,
+		)
+	];
+
+	/**
+	 * Test the widget's basic functionality - we put data in, it comes back
+	 * unchanged.
+	 *
+	 * @dataProvider validProvider
+	 */
+	public function testBasic($content)
+	{
+		// Instanciate the template
+		$etemplate = new Etemplate();
+		$etemplate->read(static::TEST_TEMPLATE, 'test');
+
+		// Set CFs
+		$etemplate->setElementAttribute('widget', 'customfields', self::cf_list);
+
+		// Send it around
+		$result = $this->mockedRoundTrip($etemplate, array('widget' => $content));
+
+		// Test it
+		$this->validateTest($result, array('widget' => $content));
+	}
+
+	/**
+	 * Test that the widget does not return a value if readonly
+	 *
+	 * @dataProvider validProvider
+	 *
+	 * It's the client that removes them here, so we can't really test without.
+	 *
+	 * public function testReadonly($content)
+	 * {
+	 * // Instanciate the template
+	 * $etemplate = new Etemplate();
+	 * $etemplate->read(static::TEST_TEMPLATE, 'test');
+	 *
+	 * // Set CFs
+	 * $etemplate->setElementAttribute('widget', 'customfields', self::cf_list);
+	 *
+	 * // Exec
+	 * $result = $this->mockedRoundTrip($etemplate, ['widget' => $content], array(), array('widget' => true));
+	 *
+	 * // Check
+	 * $this->assertEquals(array(), $result);
+	 * }
+	 */
+
+	/**
+	 * @dataProvider validProvider
+	 * @return void
+	 * @throws \Exception
+	 */
+	public function testPrivateFilter($content)
+	{
+		// Instanciate the template
+		$etemplate = new Etemplate();
+		$etemplate->read(static::TEST_TEMPLATE, 'test');
+
+		// Set CFs
+		$etemplate->setElementAttribute('widget', 'customfields', self::cf_list);
+
+		// Exec
+		$result = $this->mockedRoundTrip($etemplate, ['private' => true, 'widget' => $content]);
+
+		// Check for only the private field
+		$this->assertSame(['widget' => ['#private' => 'private']], $result);
+
+
+		// Now the opposite, only non-private
+		unset($content['#private']);
+		// Exec
+		$etemplate->setElementAttribute('widget', 'customfields', self::cf_list);
+		$result = $this->mockedRoundTrip($etemplate, ['private' => '0', 'widget' => $content]);
+
+		// Check for all but the private field
+		$this->assertSame(['widget' => $content], $result);
+	}
+
+	/**
+	 * Check field filtering
+	 *
+	 * @param type $content
+	 * @param type $validation_errors
+	 *
+	 * @dataProvider fieldFilterProvider
+	 */
+	public function testFieldFilter($content, $fields, $expected)
+	{
+		// Instanciate the template
+		$etemplate = new Etemplate();
+		$etemplate->read(static::TEST_TEMPLATE, 'test');
+
+		// Set CFs
+		$etemplate->setElementAttribute('widget', 'customfields', self::cf_list);
+
+		// Filter
+		$etemplate->setElementAttribute('widget', 'fields', $fields);
+
+		$content = array('widget' => $content);
+		$result = $this->mockedExec($etemplate, $content);
+
+		// Check for the load
+		$data = array();
+		foreach($result as $command)
+		{
+			if($command['type'] == 'et2_load')
+			{
+				$data = $command['data'];
+				break;
+			}
+		}
+
+		// Make sure we're sending what is expected
+		$this->assertContains(key($expected), array_keys($data['data']['content']['widget']), "Filtered field missing");
+		$this->assertEquals(current($expected), $data['data']['content']['widget'][key($expected)], "Filtered field's value missing");
+	}
+
+	/**
+	 * These are all valid, since fields are all text.
+	 * The individual widgets to their own type validation.
+	 */
+	public static function validProvider()
+	{
+		return array(
+			[['#text' => 'text', '#required' => 'required', '#private' => 'private', '#type_limited' => 'type_limited']]
+		);
+	}
+
+	/**
+	 * Check filtering each field individually, then filtering to allow all fields
+	 */
+	public function fieldFilterProvider()
+	{
+		$field_values = CustomfieldsTest::validProvider()[0][0];
+		$field_filters = array();
+		foreach(CustomfieldsTest::cf_list as $field_name => $field)
+		{
+			$field_filters[] = array(
+				$field_values,
+				$field_name,
+				['#' . $field_name => $field_values['#' . $field_name]]
+			);
+		}
+		$field_filters[] = array(
+			$field_values,
+			array_keys(CustomfieldsTest::cf_list),
+			$field_values
+		);
+		return $field_filters;
+	}
+}