Add `ActiveModel::Validations::AbsenceValidator`, a validator to check the absence of attributes.

Add `ActiveModel::Errors#add_on_present` method. Adds error messages to present attributes.

1 files changed, 67 insertions, 0 deletions

diff --git a/activemodel/test/cases/validations/absence_validation_test.rb b/activemodel/test/cases/validations/absence_validation_test.rb
new file mode 100644
index 0000000000..c05d71de5a
--- /dev/null
+++ b/activemodel/test/cases/validations/absence_validation_test.rb
@@ -0,0 +1,67 @@
+# encoding: utf-8
+require 'cases/helper'
+require 'models/topic'
+require 'models/person'
+require 'models/custom_reader'
+
+class AbsenceValidationTest < ActiveModel::TestCase
+  teardown do
+    Topic.reset_callbacks(:validate)
+    Person.reset_callbacks(:validate)
+    CustomReader.reset_callbacks(:validate)
+  end
+
+  def test_validate_absences
+    Topic.validates_absence_of(:title, :content)
+    t = Topic.new
+    t.title = "foo"
+    t.content = "bar"
+    assert t.invalid?
+    assert_equal ["must be blank"], t.errors[:title]
+    assert_equal ["must be blank"], t.errors[:content]
+    t.title = ""
+    t.content  = "something"
+    assert t.invalid?
+    assert_equal ["must be blank"], t.errors[:content]
+    t.content = ""
+    assert t.valid?
+  end
+
+  def test_accepts_array_arguments
+    Topic.validates_absence_of %w(title content)
+    t = Topic.new
+    t.title = "foo"
+    t.content = "bar"
+    assert t.invalid?
+    assert_equal ["must be blank"], t.errors[:title]
+    assert_equal ["must be blank"], t.errors[:content]
+  end
+
+  def test_validates_acceptance_of_with_custom_error_using_quotes
+    Person.validates_absence_of :karma, message: "This string contains 'single' and \"double\" quotes"
+    p = Person.new
+    p.karma = "good"
+    assert p.invalid?
+    assert_equal "This string contains 'single' and \"double\" quotes", p.errors[:karma].last
+  end
+
+  def test_validates_absence_of_for_ruby_class
+    Person.validates_absence_of :karma
+    p = Person.new
+    p.karma = "good"
+    assert p.invalid?
+    assert_equal ["must be blank"], p.errors[:karma]
+    p.karma = nil
+    assert p.valid?
+  end
+
+  def test_validates_absence_of_for_ruby_class_with_custom_reader
+    CustomReader.validates_absence_of :karma
+    p = CustomReader.new
+    p[:karma] = "excellent"
+    assert p.invalid?
+    assert_equal ["must be blank"], p.errors[:karma]
+    p[:karma] = ""
+    assert p.valid?
+  end
+end