block_test.module

<?php


/**
 * @file
 * Provide test blocks.
 */
use Drupal\Core\Block\BlockPluginInterface;
use Drupal\Core\Cache\Cache;

/**
 * Implements hook_block_alter().
 */
function block_test_block_alter(&$block_info) {
    if (\Drupal::state()->get('block_test_info_alter') && isset($block_info['test_block_instantiation'])) {
        $block_info['test_block_instantiation']['category'] = t('Custom category');
    }
}

/**
 * Implements hook_block_view_BASE_BLOCK_ID_alter().
 */
function block_test_block_view_test_cache_alter(array &$build, BlockPluginInterface $block) {
    if (\Drupal::state()->get('block_test_view_alter_suffix') !== NULL) {
        $build['#attributes']['foo'] = 'bar';
    }
    if (\Drupal::state()->get('block_test_view_alter_append_pre_render_prefix') !== NULL) {
        $build['#pre_render'][] = '\\Drupal\\block_test\\BlockRenderAlterContent::preRender';
    }
}

/**
 * Implements hook_block_build_BASE_BLOCK_ID_alter().
 */
function block_test_block_build_test_cache_alter(array &$build, BlockPluginInterface $block) {
    // Test altering cache keys, contexts, tags and max-age.
    if (\Drupal::state()->get('block_test_block_alter_cache_key') !== NULL) {
        $build['#cache']['keys'][] = \Drupal::state()->get('block_test_block_alter_cache_key');
    }
    if (\Drupal::state()->get('block_test_block_alter_cache_context') !== NULL) {
        $build['#cache']['contexts'][] = \Drupal::state()->get('block_test_block_alter_cache_context');
    }
    if (\Drupal::state()->get('block_test_block_alter_cache_tag') !== NULL) {
        $build['#cache']['tags'] = Cache::mergeTags($build['#cache']['tags'], [
            \Drupal::state()->get('block_test_block_alter_cache_tag'),
        ]);
    }
    if (\Drupal::state()->get('block_test_block_alter_cache_max_age') !== NULL) {
        $build['#cache']['max-age'] = \Drupal::state()->get('block_test_block_alter_cache_max_age');
    }
    // Test setting #create_placeholder.
    if (\Drupal::state()->get('block_test_block_alter_create_placeholder') !== NULL) {
        $build['#create_placeholder'] = \Drupal::state()->get('block_test_block_alter_create_placeholder');
    }
}