_s: Add featured images to Post and Pages with the ability to hide them via Content Options.

_s: Fix Travis CI error

_s: Add missing coma in array

inc/jetpack.php

@@ -27,7 +27,7 @@ function _s_jetpack_setup() {
 
 	// Add theme support for Content Options.
 	add_theme_support( 'jetpack-content-options', array(
-		'post-details' => array(
+		'post-details'    => array(
 			'stylesheet' => '_s-style',
 			'date'       => '.posted-on',
 			'categories' => '.cat-links',
@@ -35,6 +35,11 @@ function _s_jetpack_setup() {
 			'author'     => '.byline',
 			'comment'    => '.comments-link',
 		),
+		'featured-images' => array(
+			'archive'    => true,
+			'post'       => true,
+			'page'       => true,
+		),
 	) );
 }
 add_action( 'after_setup_theme', '_s_jetpack_setup' );

inc/template-tags.php

@@ -100,3 +100,36 @@ if ( ! function_exists( '_s_entry_footer' ) ) :
 		);
 	}
 endif;
+
+if ( ! function_exists( '_s_post_thumbnail' ) ) :
+/**
+ * Displays an optional post thumbnail.
+ *
+ * Wraps the post thumbnail in an anchor element on index views, or a div
+ * element when on single views.
+ */
+function _s_post_thumbnail() {
+	if ( post_password_required() || is_attachment() || ! has_post_thumbnail() ) {
+		return;
+	}
+
+	if ( is_singular() ) :
+	?>
+
+	<div class="post-thumbnail">
+		<?php the_post_thumbnail(); ?>
+	</div><!-- .post-thumbnail -->
+
+	<?php else : ?>
+
+	<a class="post-thumbnail" href="<?php the_permalink(); ?>" aria-hidden="true">
+		<?php
+			the_post_thumbnail( 'post-thumbnail', array(
+				'alt' => the_title_attribute( 'echo=0' ),
+			) );
+		?>
+	</a>
+
+	<?php endif; // End is_singular().
+}
+endif;

template-parts/content-page.php

@@ -14,6 +14,8 @@
 		<?php the_title( '<h1 class="entry-title">', '</h1>' ); ?>
 	</header><!-- .entry-header -->
 
+	<?php _s_post_thumbnail(); ?>
+
 	<div class="entry-content">
 		<?php
 			the_content();

template-parts/content-search.php

@@ -20,6 +20,8 @@
 		<?php endif; ?>
 	</header><!-- .entry-header -->
 
+	<?php _s_post_thumbnail(); ?>
+
 	<div class="entry-summary">
 		<?php the_excerpt(); ?>
 	</div><!-- .entry-summary -->

template-parts/content.php

@@ -26,6 +26,8 @@
 		endif; ?>
 	</header><!-- .entry-header -->
 
+	<?php _s_post_thumbnail(); ?>
+
 	<div class="entry-content">
 		<?php
 			the_content( sprintf(