test: cover OrmHabtmTest and teardown

test/test_orm_habtm.rb

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+require 'minitest/autorun'
+require 'prism'
+require 'tmpdir'
+
+class OrmHabtmTest < Minitest::Test
+  def setup
+    @dir = Dir.mktmpdir('prism-habtm-store')
+    @store = Prism::Orm::Store.new(File.join(@dir, 'test.pstore'))
+    @store.create_table(:students, %w[id name])
+    @store.create_table(:courses, %w[id title])
+    @store.create_table(:courses_students, %w[id course_id student_id])
+
+    student_class = Class.new(Prism::Orm::Model) do
+      table_name :students
+      has_and_belongs_to_many :courses, class_name: 'Course', join_table: 'courses_students',
+                                         foreign_key: 'student_id', association_foreign_key: 'course_id'
+    end
+    course_class = Class.new(Prism::Orm::Model) do
+      table_name :courses
+      has_and_belongs_to_many :students, class_name: 'Student', join_table: 'courses_students',
+                                          foreign_key: 'course_id', association_foreign_key: 'student_id'
+    end
+    student_class.store = @store
+    course_class.store = @store
+    Object.const_set(:Student, student_class)
+    Object.const_set(:Course, course_class)
+  end
+
+  def teardown
+    FileUtils.remove_entry(@dir)
+    %i[Student Course].each { |name| Object.send(:remove_const, name) if Object.const_defined?(name) }
+  end
+
+  def test_adding_and_reading_from_both_sides
+    alice = Student.create!(name: 'alice')
+    bob = Student.create!(name: 'bob')
+    math = Course.create!(title: 'math')
+    physics = Course.create!(title: 'physics')
+
+    alice.courses << math
+    alice.courses << physics
+    bob.courses << math
+
+    assert_equal %w[math physics], alice.courses.map(&:title)
+    assert_equal %w[math], bob.courses.map(&:title)
+    assert_equal %w[alice bob], math.students.map(&:name).sort
+    assert_equal %w[alice], physics.students.map(&:name)
+  end
+
+  def test_adding_twice_does_not_duplicate
+    alice = Student.create!(name: 'alice')
+    math = Course.create!(title: 'math')
+
+    alice.courses << math
+    alice.courses << math
+
+    assert_equal 1, alice.courses.count
+  end
+
+  def test_delete_removes_association_without_touching_other_side
+    alice = Student.create!(name: 'alice')
+    math = Course.create!(title: 'math')
+    alice.courses << math
+
+    alice.courses.delete(math)
+
+    assert_equal 0, alice.courses.count
+    assert Student.find(alice.id) # student itself untouched
+    assert Course.find(math.id) # course itself untouched
+  end
+
+  def test_replace_via_setter_swaps_full_set
+    alice = Student.create!(name: 'alice')
+    math = Course.create!(title: 'math')
+    physics = Course.create!(title: 'physics')
+    alice.courses << math
+
+    alice.courses = [physics]
+
+    assert_equal %w[physics], alice.courses.map(&:title)
+  end
+end