Add test for amp_print_schemaorg_metadata()

tests/php/test-amp-helper-functions.php

@@ -1728,6 +1728,27 @@ static function( $meta ) use ( $self ) {
 		$this->assertEquals( $metadata['publisher']['logo']['url'], amp_get_publisher_logo() );
 	}
 
+	/**
+	 * Test amp_print_schemaorg_metadata().
+	 *
+	 * @covers ::amp_print_schemaorg_metadata()
+	 */
+	public function test_amp_print_schemaorg_metadata() {
+		add_filter( 'amp_schemaorg_metadata', '__return_empty_array' );
+		$output = get_echo( 'amp_print_schemaorg_metadata' );
+		$this->assertEmpty( $output );
+
+		remove_filter( 'amp_schemaorg_metadata', '__return_empty_array' );
+		add_filter(
+			'amp_schemaorg_metadata',
+			static function () {
+				return [ 'foo' => 'bar' ];
+			}
+		);
+		$output = trim( get_echo( 'amp_print_schemaorg_metadata' ) );
+		$this->assertSame( '<script type="application/ld+json">{"foo":"bar"}</script>', $output );
+	}
+
 	/**
 	 * Test amp_add_admin_bar_view_link()
 	 *