Issue #2860570 by Jaesin: Add tests

Closes #2860570

tests/src/Functional/EntityBlockTest.php

+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\entity_block\Functional;
+
+use Drupal\block\Entity\Block;
+use Drupal\Tests\block_content\Functional\BlockContentTestBase;
+
+/**
+ * Tests UI when adding an Entity Block.
+ *
+ * @group entity_block
+ */
+class EntityBlockTest extends BlockContentTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = [
+    'entity_block',
+    'node',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * Tests Entity block placement.
+   *
+   * @throws \Drupal\Core\Entity\EntityStorageException
+   */
+  public function testEntityBlockPlacement(): void {
+    $session = $this->getSession();
+    $assert_session = $this->assertSession();
+
+    // Create a node type.
+    $this->drupalCreateContentType([
+      'type' => 'article',
+      'name' => 'Article',
+    ]);
+
+    $this->drupalLogin($this->adminUser);
+
+    $title = $this->randomMachineName();
+    // Create a node that will be placed.
+    $this->drupalCreateNode(['type' => 'article', 'title' => $title]);
+
+    $block = Block::create([
+      'id' => strtolower($this->randomMachineName()),
+      'theme' => 'stark',
+      'weight' => 0,
+      'status' => TRUE,
+      'region' => 'content',
+      'plugin' => 'entity_block:node',
+      'settings' => [
+        'label' => $this->randomString(),
+        'provider' => 'entity_block',
+        'label_display' => FALSE,
+        'entity' => 1,
+      ],
+      'visibility' => [],
+    ]);
+    $block->save();
+
+    $this->drupalGet('node/1');
+    // Verify title now appears twice.
+    $assert_session->pageTextMatchesCount(2, '/' . $title . '/');
+  }
+
+}