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# frozen_string_literal: true
require "cases/helper"
require "models/lesson"
require "models/student"
class HabtmDestroyOrderTest < ActiveRecord::TestCase
test "may not delete a lesson with students" do
sicp = Lesson.new(name: "SICP")
ben = Student.new(name: "Ben Bitdiddle")
sicp.students << ben
sicp.save!
assert_raises LessonError do
assert_no_difference("Lesson.count") do
sicp.destroy
end
end
assert_not_predicate sicp, :destroyed?
end
test "should not raise error if have foreign key in the join table" do
student = Student.new(name: "Ben Bitdiddle")
lesson = Lesson.new(name: "SICP")
lesson.students << student
lesson.save!
assert_nothing_raised do
student.destroy
end
end
test "not destroying a student with lessons leaves student<=>lesson association intact" do
# test a normal before_destroy doesn't destroy the habtm joins
begin
sicp = Lesson.new(name: "SICP")
ben = Student.new(name: "Ben Bitdiddle")
# add a before destroy to student
Student.class_eval do
before_destroy do
raise ActiveRecord::Rollback unless lessons.empty?
end
end
ben.lessons << sicp
ben.save!
ben.destroy
assert_not_empty ben.reload.lessons
ensure
# get rid of it so Student is still like it was
Student.reset_callbacks(:destroy)
end
end
test "not destroying a lesson with students leaves student<=>lesson association intact" do
# test a more aggressive before_destroy doesn't destroy the habtm joins and still throws the exception
sicp = Lesson.new(name: "SICP")
ben = Student.new(name: "Ben Bitdiddle")
sicp.students << ben
sicp.save!
assert_raises LessonError do
sicp.destroy
end
assert_not_empty sicp.reload.students
end
end
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