Example of using the Testimonials Widget plugin for WordPress `testimonials_widget_testimonial_html` filter.

filter.php

<?php

add_filter( 'testimonials_widget_testimonial_html', 'my_testimonials_widget_testimonial_html', 10, 6 );

// this function is a copy of Testimonials_Widget::get_testimonial_html and completely ignores what's in $content
function my_testimonials_widget_testimonial_html( $content, $testimonial, $atts, $is_list = true, $is_first = false, $widget_number = null ) {
	 $atts = wp_parse_args( $atts, Testimonials_Widget::get_defaults( true ) );
	 $atts = Testimonials_Widget_Settings::validate_settings( $atts );

	// display attributes
	$disable_quotes  = $atts['disable_quotes'];
	$do_image        = ! $atts['hide_image'] && ! empty( $testimonial['testimonial_image'] );
	$do_image_single = ! $atts['hide_image_single'];
	$keep_whitespace = $atts['keep_whitespace'];
	$remove_hentry   = $atts['remove_hentry'];

	$class = 'testimonials-widget-testimonial';
	if ( is_single() && empty( $widget_number ) ) {
		$class .= ' single';
	} elseif ( $is_list ) {
		$class .= ' list';
	} elseif ( $is_first ) {
		$class .= ' active';
	} elseif ( ! $is_first ) {
		$class .= ' display-none';
	}

	if ( $keep_whitespace )
		$class .= ' whitespace';

	if ( ! empty( $testimonial['post_id'] ) )
		$class = join( ' ', get_post_class( $class, $testimonial['post_id'] ) );
	else
		$class = 'testimonials-widget type-testimonials-widget status-publish hentry ' . $class;

	$class    = apply_filters( 'testimonials_widget_get_testimonial_html_class', $class, $testimonial, $atts, $is_list, $is_first, $widget_number );
	$div_open = '<div class="' . $class . '">';

	if ( $remove_hentry )
		$div_open = str_replace( ' hentry', '', $div_open );

	$image = '';
	if ( $do_image ) {
		$image .= '<span class="image">';
		$image .= $testimonial['testimonial_image'];
		$image .= '</span>';
	}

	if ( ! $do_image_single && 'get_single' == $atts['type'] )
		$image = '';

	$quote = Testimonials_Widget::get_quote( $testimonial, $atts, $widget_number );
	$cite  = Testimonials_Widget::get_cite( $testimonial, $atts );

	$extra = '';
	if ( ! empty( $testimonial['testimonial_extra'] ) ) {
		$extra .= '<div class="extra">';
		$extra .= $testimonial['testimonial_extra'];
		$extra .= '</div>';
	}

	$bottom_text = '';
	if ( ! empty( $atts['bottom_text'] ) ) {
		$bottom_text  = '<div class="bottom_text">';
		$bottom_text .= $atts['bottom_text'];
		$bottom_text .= '</div>';
	}

	$div_close = '</div>';

	$html = $div_open
		. $image
		. $quote
		. $cite
		. $extra
		. $bottom_text
		. $div_close;

	// not done sooner as tag_close_quote is used for Premium
	if ( $disable_quotes ) {
		$html = str_replace( Testimonials_Widget::$tag_open_quote, '', $html );
		$html = str_replace( Testimonials_Widget::$tag_close_quote, '', $html );
	}

	return $html;
}

?>