Avoid changing schema during test run

Sean's approach to dropping/re-adding the column during the test run
worked, but it had a few disadvantages:

1. it required a `before(:all)` callback, which is frowned upon by rubocop-rspec
2. more importantly, it could have prevented us from using test parallelization
  in the future
3. least importantly, it produced annoying output in the middle of the test run

spec/dummy_app/app/models/no_object.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+# Demonstrates a table that omits the `object` column.
+class NoObject < ActiveRecord::Base
+  has_paper_trail(
+    class_name: "NoObjectVersion",
+    meta: { metadatum: 42 }
+  )
+  validates :letter, length: { is: 1 }, presence: true
+end

spec/dummy_app/app/versions/no_object_version.rb

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+# Demonstrates a table that omits the `object` column.
+class NoObjectVersion < ::PaperTrail::Version
+  self.table_name = "no_object_versions"
+end

spec/dummy_app/db/migrate/20110208155312_set_up_test_tables.rb

@@ -124,6 +124,24 @@ class SetUpTestTables < (
     end
     add_index :post_versions, %i[item_type item_id]
 
+    # Uses custom versions table `no_object_versions`.
+    create_table :no_objects, force: true do |t|
+      t.string :letter, null: false, limit: 1
+      t.timestamps null: false, limit: 6
+    end
+
+    # This table omits the `object` column.
+    create_table :no_object_versions, force: true do |t|
+      t.string   :item_type, null: false
+      t.integer  :item_id,   null: false
+      t.string   :event,     null: false
+      t.string   :whodunnit
+      t.datetime :created_at, limit: 6
+      t.text     :object_changes, limit: TEXT_BYTES
+      t.integer  :metadatum
+    end
+    add_index :no_object_versions, %i[item_type item_id]
+
     if ENV["DB"] == "postgres"
       create_table :json_versions, force: true do |t|
         t.string   :item_type, null: false

spec/models/no_object_spec.rb

@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe NoObject, versioning: true do
+  it "still creates version records" do
+    n = described_class.create!(letter: "A")
+    a = n.versions.last.attributes
+    expect(a).not_to include "object"
+    expect(a["event"]).to eq "create"
+    expect(a["object_changes"]).to start_with("---")
+    expect(a["metadatum"]).to eq(42)
+
+    n.update!(letter: "B")
+    a = n.versions.last.attributes
+    expect(a).not_to include "object"
+    expect(a["event"]).to eq "update"
+    expect(a["object_changes"]).to start_with("---")
+    expect(a["metadatum"]).to eq(42)
+
+    n.destroy!
+    a = n.versions.last.attributes
+    expect(a).not_to include "object"
+    expect(a["event"]).to eq "destroy"
+    expect(a["object_changes"]).to be_nil
+    expect(a["metadatum"]).to eq(42)
+  end
+
+  describe "reify" do
+    it "raises error" do
+      n = NoObject.create!(letter: "A")
+      v = n.versions.last
+      expect { v.reify }.to(
+        raise_error(
+          ::RuntimeError,
+          "reify can't be called without an object column"
+        )
+      )
+    end
+  end
+
+  describe "where_object" do
+    it "raises error" do
+      n = NoObject.create!(letter: "A")
+      expect {
+        n.versions.where_object(foo: "bar")
+      }.to(
+        raise_error(
+          ::RuntimeError,
+          "where_object can't be called without an object column"
+        )
+      )
+    end
+  end
+end

spec/paper_trail/model_spec.rb

@@ -877,55 +877,4 @@ RSpec.describe(::PaperTrail, versioning: true) do
       expect(widget.versions.empty?).to(eq(true))
     end
   end
-
-  context "without the object column" do
-    # rubocop:disable RSpec/BeforeAfterAll
-    before :all do
-      ActiveRecord::Migration.remove_column :versions, :object
-      PaperTrail::Version.reset_column_information
-    end
-    after :all do
-      ActiveRecord::Migration.add_column :versions, :object, :text
-      PaperTrail::Version.reset_column_information
-    end
-    # rubocop:enable RSpec/BeforeAfterAll
-
-    it "versions are created" do
-      song = Song.create length: 4
-      version = song.versions.last.attributes
-      expect(version).not_to include "object"
-      expect(version["event"]).to eq "create"
-      expect(version["object_changes"]).to start_with("---")
-
-      song.update length: 5
-      version = song.versions.last.attributes
-      expect(version).not_to include "object"
-      expect(version["event"]).to eq "update"
-      expect(version["object_changes"]).to start_with("---")
-
-      song.destroy
-      version = song.versions.last.attributes
-      expect(version).not_to include "object"
-      expect(version["event"]).to eq "destroy"
-      expect(version["object_changes"]).to eq nil
-    end
-
-    it "reify doesn't work" do
-      song = Song.create length: 4
-      song.update length: 5
-
-      expect do
-        song.versions.first.reify
-      end.to raise_error "reify can't be called without an object column"
-    end
-
-    it "where_object doesn't work" do
-      song = Song.create length: 4
-      song.update length: 5
-
-      expect do
-        song.versions.where_object length: 4
-      end.to raise_error "where_object can't be called without an object column"
-    end
-  end
 end