diff --git a/web/modules/custom/custom/src/Entity/Node/Post.php b/web/modules/custom/custom/src/Entity/Node/Post.php
index 00b6527..c41e908 100644
--- a/web/modules/custom/custom/src/Entity/Node/Post.php
+++ b/web/modules/custom/custom/src/Entity/Node/Post.php
@@ -4,8 +4,8 @@ declare(strict_types=1);
 
 namespace Drupal\custom\Entity\Node;
 
-use Drupal\node\Entity\Node;
 use Drupal\discoverable_entity_bundle_classes\ContentEntityBundleInterface;
+use Drupal\node\Entity\Node;
 
 /**
  * Defines an blog post node class.
diff --git a/web/modules/custom/custom/tests/modules/opdavies_posts_test/config/install/field.field.node.post.field_has_tweet.yml b/web/modules/custom/custom/tests/modules/opdavies_posts_test/config/install/field.field.node.post.field_has_tweet.yml
new file mode 100644
index 0000000..0cb9942
--- /dev/null
+++ b/web/modules/custom/custom/tests/modules/opdavies_posts_test/config/install/field.field.node.post.field_has_tweet.yml
@@ -0,0 +1,22 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - field.storage.node.field_has_tweet
+    - node.type.post
+id: node.post.field_has_tweet
+field_name: field_has_tweet
+entity_type: node
+bundle: post
+label: 'Has tweet'
+description: 'Check to include Twitter''s widget.js script for this page.'
+required: false
+translatable: false
+default_value:
+  -
+    value: 0
+default_value_callback: ''
+settings:
+  on_label: 'Yes'
+  off_label: 'No'
+field_type: boolean
diff --git a/web/modules/custom/custom/tests/modules/opdavies_posts_test/config/install/field.storage.node.field_has_tweet.yml b/web/modules/custom/custom/tests/modules/opdavies_posts_test/config/install/field.storage.node.field_has_tweet.yml
new file mode 100644
index 0000000..c62bbf5
--- /dev/null
+++ b/web/modules/custom/custom/tests/modules/opdavies_posts_test/config/install/field.storage.node.field_has_tweet.yml
@@ -0,0 +1,17 @@
+langcode: en
+status: true
+dependencies:
+  module:
+    - node
+id: node.field_has_tweet
+field_name: field_has_tweet
+entity_type: node
+type: boolean
+settings: {  }
+module: core
+locked: false
+cardinality: 1
+translatable: true
+indexes: {  }
+persist_with_no_fields: false
+custom_storage: false
diff --git a/web/modules/custom/custom/tests/modules/opdavies_posts_test/config/install/node.type.post.yml b/web/modules/custom/custom/tests/modules/opdavies_posts_test/config/install/node.type.post.yml
new file mode 100644
index 0000000..cec4a65
--- /dev/null
+++ b/web/modules/custom/custom/tests/modules/opdavies_posts_test/config/install/node.type.post.yml
@@ -0,0 +1,11 @@
+langcode: en
+status: true
+dependencies: { }
+third_party_settings: { }
+name: 'Blog post'
+type: post
+description: 'A single blog post.'
+help: ''
+new_revision: true
+preview_mode: 1
+display_submitted: true
diff --git a/web/modules/custom/custom/tests/modules/opdavies_posts_test/opdavies_posts_test.info.yml b/web/modules/custom/custom/tests/modules/opdavies_posts_test/opdavies_posts_test.info.yml
new file mode 100644
index 0000000..e2f18b2
--- /dev/null
+++ b/web/modules/custom/custom/tests/modules/opdavies_posts_test/opdavies_posts_test.info.yml
@@ -0,0 +1,4 @@
+name: Oliver Davies Posts Test
+type: module
+core_version_requirement: ^8 || ^9
+hidden: true
diff --git a/web/modules/custom/custom/tests/src/Kernel/Entity/Node/PostTest.php b/web/modules/custom/custom/tests/src/Kernel/Entity/Node/PostTest.php
new file mode 100644
index 0000000..665587b
--- /dev/null
+++ b/web/modules/custom/custom/tests/src/Kernel/Entity/Node/PostTest.php
@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\custom\Kernel\Entity\Node;
+
+use Drupal\custom\Entity\Node\Post;
+use Drupal\KernelTests\Core\Entity\EntityKernelTestBase;
+use Drupal\node\Entity\Node;
+
+final class PostTest extends EntityKernelTestBase {
+
+  public static $modules = [
+    // Core.
+    'node',
+
+    // Contrib.
+    'discoverable_entity_bundle_classes',
+
+    // Custom.
+    'custom',
+    'opdavies_posts_test',
+  ];
+
+  /** @test */
+  public function it_can_determine_if_a_post_contains_a_tweet(): void {
+    /** @var Post $post */
+    $post = Node::create(['type' => 'post']);
+    $this->assertFalse($post->hasTweet());
+
+    /** @var Post $post */
+    $post = Node::create([
+      'field_has_tweet' => TRUE,
+      'type'  => 'post',
+    ]);
+    $this->assertTrue($post->hasTweet());
+  }
+
+  protected function setUp() {
+    parent::setUp();
+
+    $this->installConfig(['opdavies_posts_test']);
+  }
+
+}