1 files changed, 40 insertions, 0 deletions
diff --git a/activemodel/test/cases/errors_test.rb b/activemodel/test/cases/errors_test.rb
index 6ff3be1308..f9015b869d 100644
--- a/activemodel/test/cases/errors_test.rb
+++ b/activemodel/test/cases/errors_test.rb
@@ -185,6 +185,12 @@ class ErrorsTest < ActiveModel::TestCase
     assert person.errors.added?(:name, :blank)
   end
 
+  test "added? returns true when string attribute is used with a symbol message" do
+    person = Person.new
+    person.errors.add(:name, :blank)
+    assert person.errors.added?("name", :blank)
+  end
+
   test "added? handles proc messages" do
     person = Person.new
     message = Proc.new { "cannot be blank" }
@@ -222,6 +228,16 @@ class ErrorsTest < ActiveModel::TestCase
     assert_not person.errors.added?(:name)
   end
 
+  test "added? returns false when checking for an error with an incorrect or missing option" do
+    person = Person.new
+    person.errors.add :name, :too_long, count: 25
+
+    assert person.errors.added? :name, :too_long, count: 25
+    assert_not person.errors.added? :name, :too_long, count: 24
+    assert_not person.errors.added? :name, :too_long
+    assert_not person.errors.added? :name, "is too long"
+  end
+
   test "added? returns false when checking for an error by symbol and a different error with same message is present" do
     I18n.backend.store_translations("en", errors: { attributes: { name: { wrong: "is wrong", used: "is wrong" } } })
     person = Person.new
@@ -395,6 +411,30 @@ class ErrorsTest < ActiveModel::TestCase
     assert_equal({ name: [{ error: :blank }, { error: :invalid }] }, person.errors.details)
   end
 
+  test "slice! removes all errors except the given keys" do
+    person = Person.new
+    person.errors.add(:name, "cannot be nil")
+    person.errors.add(:age, "cannot be nil")
+    person.errors.add(:gender, "cannot be nil")
+    person.errors.add(:city, "cannot be nil")
+
+    person.errors.slice!(:age, "gender")
+
+    assert_equal [:age, :gender], person.errors.keys
+  end
+
+  test "slice! returns the deleted errors" do
+    person = Person.new
+    person.errors.add(:name, "cannot be nil")
+    person.errors.add(:age, "cannot be nil")
+    person.errors.add(:gender, "cannot be nil")
+    person.errors.add(:city, "cannot be nil")
+
+    removed_errors = person.errors.slice!(:age, "gender")
+
+    assert_equal({ name: ["cannot be nil"], city: ["cannot be nil"] }, removed_errors)
+  end
+
   test "errors are marshalable" do
     errors = ActiveModel::Errors.new(Person.new)
     errors.add(:name, :invalid)