Added more associations tests

test/associations_test.rb

@@ -24,19 +24,37 @@ def test_period
     assert_equal expected, user.posts.group_by_period(:day, :created_at).count
   end
 
+  def test_includes
+    user = create_user("2014-03-01")
+    user.posts.create!(created_at: "2014-04-01 00:00:00 UTC")
+    expected = {
+      Date.parse("2014-03-01") => 1
+    }
+    assert_equal expected, User.includes(:posts).group_by_month(:created_at).count("posts.id")
+  end
+
   # https://github.com/ankane/groupdate/issues/222#issuecomment-914343044
-  def test_left_outer_joins
+  def test_includes_where
     date = 11.months.ago.in_time_zone(utc).to_date
     create_user(date.to_s)
-    result = User.left_outer_joins(:posts).where(posts: {id: nil}).group_by_month(:created_at, last: 12, format: "%B").count
+    result = User.includes(:posts).where(posts: {id: nil}).group_by_month(:created_at, last: 12, format: "%B").count
     assert_equal 1, result[date.strftime("%B")]
   end
 
+  def test_joins
+    user = create_user("2014-03-01")
+    user.posts.create!(created_at: "2014-04-01 00:00:00 UTC")
+    expected = {
+      Date.parse("2014-03-01") => 1
+    }
+    assert_equal expected, User.joins(:posts).group_by_month(:created_at).count("posts.id")
+  end
+
   # https://github.com/ankane/groupdate/issues/222#issuecomment-914343044
-  def test_includes
+  def test_left_outer_joins
     date = 11.months.ago.in_time_zone(utc).to_date
     create_user(date.to_s)
-    result = User.includes(:posts).where(posts: {id: nil}).group_by_month(:created_at, last: 12, format: "%B").count
+    result = User.left_outer_joins(:posts).where(posts: {id: nil}).group_by_month(:created_at, last: 12, format: "%B").count
     assert_equal 1, result[date.strftime("%B")]
   end
 end