added more specs and fixed formatting

extensions/guardian.rb

@@ -9,7 +9,7 @@ module CustomWizardGuardian
   end
 
   def can_create_post?(parent)
-    result = parent.present? ? wizard_user_can_create_topic_on_category?(parent) : false 
+    result = parent.present? ? wizard_user_can_create_topic_on_category?(parent) : false
     result || super
   end
 
@@ -23,7 +23,7 @@ module CustomWizardGuardian
   def creating_wizard(topic)
     wizard_id = topic.wizard_created.presence
     wizard = CustomWizard::Builder.new(wizard_id, @user).build if wizard_id
-    return wizard.presence
+    wizard.presence
   end
 
   def wizard_can_create_topic_on_category?(wizard, topic)

spec/extensions/guardian_extension_spec.rb

@@ -2,7 +2,7 @@
 require_relative '../plugin_helper'
 
 describe ::Guardian do
-  fab!(:user) { 
+  fab!(:user) {
     Fabricate(:user, name: "Angus", username: 'angus', email: "angus@email.com")
   }
   fab!(:category) { Fabricate(:category, name: 'cat1', slug: 'cat-slug') }
@@ -65,4 +65,31 @@ describe ::Guardian do
       expect(user.guardian.send(:wizard_user_can_create_topic_on_category?, topic)).to be_falsey
     end
   end
+
+  context "the wizard can't create a topic in the category" do
+    it "restricts editing the topic first post" do
+      wizard = CustomWizard::Builder.new(@template[:id], user).build
+      wizard.create_updater(
+        wizard.steps.first.id,
+        step_1_field_1: "Topic Title",
+        step_1_field_2: "topic body"
+      ).update
+      wizard.create_updater(wizard.steps.second.id, {}).update
+      wizard.create_updater(wizard.steps.last.id,
+        step_3_field_3: category.id
+      ).update
+
+      topic = Topic.where(
+        title: "Topic Title",
+        category_id: category.id
+      ).first
+
+      new_category = Fabricate(:category)
+      topic.category_id = new_category.id
+      topic.save
+      topic.reload
+
+      expect(user.guardian.send(:wizard_user_can_create_topic_on_category?, topic)).to be_falsey
+    end
+  end
 end