add PostTypeRegistrar tests

.editorconfig

@@ -0,0 +1,8 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+indent_style = space

src/Registrars/PostTypeRegistrar.php

@@ -31,7 +31,7 @@ public function register()
         // modify filters on the admin edit screen
         add_action('restrict_manage_posts', [$this, 'modifyFilters'], 10, 1);
 
-        if (isset($this->columns)) {
+        if (isset($this->posttype->columns)) {
             // modify the admin edit columns.
             add_filter('manage_' . $name . '_posts_columns', [$this, 'modifyColumns'], 10, 1);
 
@@ -85,7 +85,7 @@ public function modifyPostType(array $args, string $posttype)
      */
     public function registerTaxonomies()
     {
-        if (empty($this->taxonomies)) {
+        if (empty($this->posttype->taxonomies)) {
             return;
         }
 
@@ -168,7 +168,7 @@ public function modifyColumns($columns)
      */
     public function populateColumns($column, $post_id)
     {
-        if (isset($this->columns->populate[$column])) {
+        if (isset($this->posttype->columns->populate[$column])) {
             call_user_func_array($this->posttype->columns()->populate[$column], [$column, $post_id]);
         }
     }

tests/Registrars/PostTypeRegistrarTest.php

@@ -0,0 +1,24 @@
+<?php
+
+use PHPUnit\Framework\TestCase;
+use PostTypes\PostType;
+use PostTypes\Registrars\PostTypeRegistrar;
+
+class PostTypeRegistrarTest extends TestCase
+{
+    /** @test */
+    public function canModifyPostType()
+    {
+        $posttype = new PostType('post', [
+            'public' => false,
+        ]);
+
+        $registrar = new PostTypeRegistrar($posttype);
+
+        $options = $registrar->modifyPostType([
+            'public' => true,
+        ], 'post');
+
+        $this->assertEquals(false, $options['public']);
+    }
+}