Fix unit test for JForm

JFormTest.php

	public function testValidateField()
	{
		$form = new JFormInspector('form1');

		$this->assertThat(
			$form->load(JFormDataHelper::$validateFieldDocument),
			$this->isTrue(),
			'Line:'.__LINE__.' XML string should load successfully.'
		);

		$xml = $form->getXML();

		// Test error handling.
		try
		{
			$result = $form->validateField('wrong');
			$this->fail('Line:'.__LINE__.' Passing a non-JXmlElement should return an exception.');
		}
		catch (InvalidArgumentException $result)
		{
			$this->assertThat(
				$result->getMessage(),
				$this->equalTo('JLIB_FORM_ERROR_VALIDATE_FIELD'),
				'Line:'.__LINE__.' The correct exception should be returned.'
			);
		}

		try
		{
			$field = array_pop($xml->xpath('fields/field[@name="missingrule"]'));
			$result = $form->validateField($field, null, 'value');
			$this->fail('Line:'.__LINE__.' Having a missing validation rule should return an exception.');
		}
		catch (InvalidArgumentException $result)
		{
			$this->assertThat(
				$result->getMessage(),
				$this->equalTo('JLIB_FORM_VALIDATE_FIELD_RULE_MISSING'),
				'Line:'.__LINE__.' The correct exception should be returned.'
			);
		}

		try
		{
			$field = array_pop($xml->xpath('fields/field[@name="boolean"]'));
			$result = $form->validateField($field);
			$this->fail('Line:'.__LINE__.' A failed validation should return an exception.');
		}
		catch (RuntimeException $result)
		{
			$this->assertThat(
				$result->getMessage(),
				$this->equalTo('JLIB_FORM_VALIDATE_FIELD_INVALID'),
				'Line:'.__LINE__.' The correct exception should be returned.'
			);
		}

		try
		{
			$field = array_pop($xml->xpath('fields/field[@name="required"]'));
			$result = $form->validateField($field);
			$this->fail('Line:'.__LINE__.' A required field missing a value should return an exception.');
		}
		catch (RuntimeException $result)
		{
			$this->assertThat(
				$result->getMessage(),
				$this->equalTo('JLIB_FORM_VALIDATE_FIELD_REQUIRED'),
				'Line:'.__LINE__.' The correct exception should be returned.'
			);
		}

		// Test general usage.

		$field = array_pop($xml->xpath('fields/field[@name="boolean"]'));
		$this->assertThat(
			$form->validateField($field, null, 'true'),
			$this->isTrue(),
			'Line:'.__LINE__.' A field with a passing validate attribute set should return true.'
		);

		$field = array_pop($xml->xpath('fields/field[@name="optional"]'));
		$this->assertThat(
			$form->validateField($field),
			$this->isTrue(),
			'Line:'.__LINE__.' A field without required set should return true.'
		);

		$field = array_pop($xml->xpath('fields/field[@name="required"]'));
		$this->assertThat(
			$form->validateField($field, null, 'value'),
			$this->isTrue(),
			'Line:'.__LINE__.' A required field with a value should return true.'
		);
	}