test: capture logs in tests, test various atomic behaviors

test/ash_postgres_test.exs

@@ -5,6 +5,9 @@ defmodule AshPostgresTest do
   test "transaction metadata is given to on_transaction_begin" do
     AshPostgres.Test.Post
     |> Ash.Changeset.for_create(:create, %{title: "title"})
+    |> Ash.Changeset.after_action(fn _, result ->
+      {:ok, result}
+    end)
     |> Ash.create!()
 
     assert_receive %{
@@ -62,7 +65,7 @@ defmodule AshPostgresTest do
           actor: nil,
           actor: author
         )
-        |> then(&AshPostgres.Test.Post.can_update_if_author?(author, &1))
+        |> then(&AshPostgres.Test.Post.can_update_if_author?(author, &1, reuse_values?: true))
       end)
 
     assert log == ""

test/support/resources/post.ex

@@ -159,6 +159,28 @@ defmodule AshPostgres.Test.Post do
       change(atomic_update(:limited_score, expr((limited_score || 0) + ^arg(:amount))))
     end
 
+    update :change_nothing do
+      accept([])
+      require_atomic?(false)
+      change(fn changeset, _ -> changeset end)
+    end
+
+    update :change_nothing_atomic do
+      accept([])
+      require_atomic?(true)
+    end
+
+    update :change_title do
+      accept([:title])
+      require_atomic?(false)
+      change(fn changeset, _ -> changeset end)
+    end
+
+    update :change_title_atomic do
+      accept([:title])
+      require_atomic?(true)
+    end
+
     destroy :destroy_only_freds do
       change(filter(expr(title == "fred")))
     end

test/support/test_repo.ex

@@ -7,7 +7,7 @@ defmodule AshPostgres.TestRepo do
     send(self(), data)
   end
 
-  def prefer_transaction?, do: true
+  def prefer_transaction?, do: false
 
   def prefer_transaction_for_atomic_updates?, do: false
 

test/test_helper.exs

@@ -1,4 +1,6 @@
-ExUnit.start()
+ExUnit.start(capture_log: true)
+
+Logger.configure(level: :debug)
 
 exclude_tags =
   case System.get_env("PG_VERSION") do

test/update_test.exs

@@ -2,6 +2,8 @@ defmodule AshPostgres.UpdateTest do
   use AshPostgres.RepoCase, async: false
   alias AshPostgres.Test.Post
   require Ash.Query
+  import ExUnit.CaptureLog
+  import Ash.Expr
 
   test "can update with nested maps" do
     Post
@@ -60,6 +62,99 @@ defmodule AshPostgres.UpdateTest do
     |> Ash.update!()
   end
 
+  test "timestamps arent updated if there are no changes non-atomically" do
+    post =
+      AshPostgres.Test.Post
+      |> Ash.Changeset.for_create(:create, %{title: "match"})
+      |> Ash.create!()
+
+    post2 =
+      post
+      |> Ash.update!(action: :change_nothing)
+
+    assert post.updated_at == post2.updated_at
+  end
+
+  test "no queries are run if there are no changes non-atomically" do
+    post =
+      AshPostgres.Test.Post
+      |> Ash.Changeset.for_create(:create, %{title: "match"})
+      |> Ash.create!()
+
+    assert "" =
+             capture_log(fn ->
+               post
+               |> Ash.update!(action: :change_nothing)
+             end)
+  end
+
+  test "queries are run if there are no changes but there are filters non-atomically" do
+    post =
+      AshPostgres.Test.Post
+      |> Ash.Changeset.for_create(:create, %{title: "match"})
+      |> Ash.create!()
+
+    assert_raise Ash.Error.Invalid, ~r/stale/, fn ->
+      post
+      |> Ash.Changeset.for_update(:change_nothing, %{})
+      |> Ash.Changeset.filter(expr(title != "match"))
+      |> Ash.update!(action: :change_nothing)
+    end
+  end
+
+  test "timestamps arent updated if there are no changes atomically" do
+    post =
+      AshPostgres.Test.Post
+      |> Ash.Changeset.for_create(:create, %{title: "match"})
+      |> Ash.create!()
+
+    post2 =
+      post
+      |> Ash.update!(action: :change_nothing_atomic)
+
+    assert post.updated_at == post2.updated_at
+  end
+
+  test "timestamps arent updated if nothing changes non-atomically" do
+    post =
+      AshPostgres.Test.Post
+      |> Ash.Changeset.for_create(:create, %{title: "match"})
+      |> Ash.create!()
+
+    post2 =
+      post
+      |> Ash.update!(%{title: "match"}, action: :change_title)
+
+    assert post.updated_at == post2.updated_at
+  end
+
+  test "timestamps arent updated if nothing changes atomically" do
+    post =
+      AshPostgres.Test.Post
+      |> Ash.Changeset.for_create(:create, %{title: "match"})
+      |> Ash.create!()
+
+    post2 =
+      post
+      |> Ash.update!(%{title: "match"}, action: :change_title_atomic)
+
+    assert post.updated_at == post2.updated_at
+  end
+
+  test "queries are run if there are no changes atomically" do
+    post =
+      AshPostgres.Test.Post
+      |> Ash.Changeset.for_create(:create, %{title: "match"})
+      |> Ash.create!()
+
+    assert_raise Ash.Error.Invalid, ~r/stale/, fn ->
+      post
+      |> Ash.Changeset.for_update(:change_nothing_atomic, %{})
+      |> Ash.Changeset.filter(expr(title != "match"))
+      |> Ash.update!(action: :change_nothing)
+    end
+  end
+
   test "can unrelate belongs_to" do
     author =
       AshPostgres.Test.Author