1 files changed, 128 insertions, 0 deletions
diff --git a/activerecord/test/cases/associations/required_test.rb b/activerecord/test/cases/associations/required_test.rb
new file mode 100644
index 0000000000..c7a78e6bc4
--- /dev/null
+++ b/activerecord/test/cases/associations/required_test.rb
@@ -0,0 +1,128 @@
+# frozen_string_literal: true
+
+require "cases/helper"
+
+class RequiredAssociationsTest < ActiveRecord::TestCase
+  self.use_transactional_tests = false
+
+  class Parent < ActiveRecord::Base
+  end
+
+  class Child < ActiveRecord::Base
+  end
+
+  setup do
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table :parents, force: true
+    @connection.create_table :children, force: true do |t|
+      t.belongs_to :parent
+    end
+  end
+
+  teardown do
+    @connection.drop_table "parents", if_exists: true
+    @connection.drop_table "children", if_exists: true
+  end
+
+  test "belongs_to associations can be optional by default" do
+    original_value = ActiveRecord::Base.belongs_to_required_by_default
+    ActiveRecord::Base.belongs_to_required_by_default = false
+
+    model = subclass_of(Child) do
+      belongs_to :parent, inverse_of: false,
+        class_name: "RequiredAssociationsTest::Parent"
+    end
+
+    assert model.new.save
+    assert model.new(parent: Parent.new).save
+  ensure
+    ActiveRecord::Base.belongs_to_required_by_default = original_value
+  end
+
+  test "required belongs_to associations have presence validated" do
+    model = subclass_of(Child) do
+      belongs_to :parent, required: true, inverse_of: false,
+        class_name: "RequiredAssociationsTest::Parent"
+    end
+
+    record = model.new
+    assert_not record.save
+    assert_equal ["Parent must exist"], record.errors.full_messages
+
+    record.parent = Parent.new
+    assert record.save
+  end
+
+  test "belongs_to associations can be required by default" do
+    original_value = ActiveRecord::Base.belongs_to_required_by_default
+    ActiveRecord::Base.belongs_to_required_by_default = true
+
+    model = subclass_of(Child) do
+      belongs_to :parent, inverse_of: false,
+        class_name: "RequiredAssociationsTest::Parent"
+    end
+
+    record = model.new
+    assert_not record.save
+    assert_equal ["Parent must exist"], record.errors.full_messages
+
+    record.parent = Parent.new
+    assert record.save
+  ensure
+    ActiveRecord::Base.belongs_to_required_by_default = original_value
+  end
+
+  test "has_one associations are not required by default" do
+    model = subclass_of(Parent) do
+      has_one :child, inverse_of: false,
+        class_name: "RequiredAssociationsTest::Child"
+    end
+
+    assert model.new.save
+    assert model.new(child: Child.new).save
+  end
+
+  test "required has_one associations have presence validated" do
+    model = subclass_of(Parent) do
+      has_one :child, required: true, inverse_of: false,
+        class_name: "RequiredAssociationsTest::Child"
+    end
+
+    record = model.new
+    assert_not record.save
+    assert_equal ["Child must exist"], record.errors.full_messages
+
+    record.child = Child.new
+    assert record.save
+  end
+
+  test "required has_one associations have a correct error message" do
+    model = subclass_of(Parent) do
+      has_one :child, required: true, inverse_of: false,
+      class_name: "RequiredAssociationsTest::Child"
+    end
+
+    record = model.create
+    assert_equal ["Child must exist"], record.errors.full_messages
+  end
+
+  test "required belongs_to associations have a correct error message" do
+    model = subclass_of(Child) do
+      belongs_to :parent, required: true, inverse_of: false,
+      class_name: "RequiredAssociationsTest::Parent"
+    end
+
+    record = model.create
+    assert_equal ["Parent must exist"], record.errors.full_messages
+  end
+
+  private
+
+    def subclass_of(klass, &block)
+      subclass = Class.new(klass, &block)
+      def subclass.name
+        superclass.name
+      end
+      subclass
+    end
+end