activeadmin
diff --git a/‎spec/unit/async_count_spec.rb
Lines changed: 13 additions & 6 deletions b/‎spec/unit/async_count_spec.rb
Lines changed: 13 additions & 6 deletions
diff --git a/‎spec/unit/views/components/scopes_spec.rb
Lines changed: 1 addition & 1 deletion b/‎spec/unit/views/components/scopes_spec.rb
Lines changed: 1 addition & 1 deletion
@@ -1,7 +1,11 @@
 # frozen_string_literal: true
 module ActiveAdmin
   class AsyncCount
+    class NotSupportedError < RuntimeError; end
+
     def initialize(collection)
+      raise NotSupportedError, "#{collection.inspect} does not support :async_count" unless collection.respond_to?(:async_count)
+
       @collection = collection.except(:select, :order)
       @promise = @collection.async_count
     end
 
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 require "rails_helper"
 
-RSpec.describe ActiveAdmin::AsyncCount, if: Post.respond_to?(:async_count) do
+RSpec.describe ActiveAdmin::AsyncCount do
   include ActiveAdmin::IndexHelper
 
   def seed_posts
@@ -10,22 +10,29 @@ def seed_posts
     end
   end
 
-  it "can be passed to the collection_size helper" do
+  it "can be passed to the collection_size helper", if: Post.respond_to?(:async_count) do
     seed_posts
 
     expect(collection_size(described_class.new(Post.all))).to eq(Post.count)
     expect(collection_size(described_class.new(Post.group(:author_id)))).to eq(Post.distinct.pluck(:author_id).size)
   end
 
   describe "#initialize" do
-    it "initiates an async_count query" do
-      collection = Post.all
+    let(:collection) { Post.all }
+
+    it "initiates an async_count query", if: Post.respond_to?(:async_count) do
       expect(collection).to receive(:async_count)
       described_class.new(collection)
     end
+
+    it "raises an error when ActiveRecord async_count is unavailable", unless: Post.respond_to?(:async_count) do
+      expect do
+        described_class.new(collection)
+      end.to raise_error(ActiveAdmin::AsyncCount::NotSupportedError, %r{does not support :async_count})
+    end
   end
 
-  describe "#count" do
+  describe "#count", if: Post.respond_to?(:async_count) do
     before { seed_posts }
 
     it "returns the result of a count query" do
@@ -49,7 +56,7 @@ def seed_posts
     end
   end
 
-  describe "delegation" do
+  describe "delegation", if: Post.respond_to?(:async_count) do
     let(:collection) { Post.all }
 
     %i[
 
@@ -69,7 +69,7 @@
       end
 
       it "raises an error when ActiveRecord async_count is unavailable", unless: Post.respond_to?(:async_count) do
-        expect { scopes }.to raise_error(NoMethodError, %r{async_count})
+        expect { scopes }.to raise_error(ActiveAdmin::AsyncCount::NotSupportedError, %r{does not support :async_count})
       end
 
       context "when async_count is available in Rails", if: Post.respond_to?(:async_count) do