MONGOID-5661 [Monkey Patch Removal] Add test which checks for monkey patches (#5711)

* Add script to check monkey patches

* Update monkey_patches_spec.rb

* Update monkey_patches_spec.rb

---------

Co-authored-by: Jamis Buck <[email protected]>

Author: johnnyshields

spec/mongoid/criteria/queryable/extensions/symbol_spec.rb

@@ -13,6 +13,10 @@
       end
     end
 
+    after do
+      Symbol.undef_method(:fubar)
+    end
+
     let(:fubar) do
       :testing.fubar
     end

spec/mongoid/monkey_patches_spec.rb

@@ -0,0 +1,204 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+# @note This test ensures that we do not inadvertently introduce new monkey patches
+# to Mongoid. Existing monkey patch methods which are marked with +Mongoid.deprecated+
+# are excluded from this test.
+RSpec.describe('Do not add monkey patches') do # rubocop:disable RSpec/DescribeClass
+  classes = [
+    Object,
+    Array,
+    BigDecimal,
+    Date,
+    DateTime,
+    FalseClass,
+    Float,
+    Hash,
+    Integer,
+    Module,
+    NilClass,
+    Range,
+    Regexp,
+    Set,
+    String,
+    Symbol,
+    Time,
+    TrueClass,
+    ActiveSupport::TimeWithZone,
+    BSON::Binary,
+    BSON::Decimal128,
+    BSON::ObjectId,
+    BSON::Regexp,
+    BSON::Regexp::Raw
+  ]
+
+  expected_instance_methods = {
+    Object => %i[
+      __add__
+      __add_from_array__
+      __array__
+      __deep_copy__
+      __evolve_object_id__
+      __expand_complex__
+      __intersect__
+      __intersect_from_array__
+      __intersect_from_object__
+      __mongoize_object_id__
+      __mongoize_time__
+      __union__
+      __union_from_object__
+      ivar
+      mongoize
+      numeric?
+      remove_ivar
+      resizable?
+      substitutable
+    ],
+    Array => %i[
+      __evolve_date__
+      __evolve_time__
+      __sort_option__
+      __sort_pair__
+      delete_one
+    ],
+    Date => %i[
+      __evolve_date__
+      __evolve_time__
+    ],
+    DateTime => %i[
+      __evolve_date__
+      __evolve_time__
+    ],
+    FalseClass => %i[is_a?],
+    Float => %i[
+      __evolve_date__
+      __evolve_time__
+    ],
+    Hash => %i[
+      __sort_option__
+    ],
+    Integer => %i[
+      __evolve_date__
+      __evolve_time__
+    ],
+    Module => %i[
+      re_define_method
+    ],
+    NilClass => %i[
+      __evolve_date__
+      __evolve_time__
+      __expanded__
+      __override__
+      collectionize
+    ],
+    Range => %i[
+      __evolve_date__
+      __evolve_range__
+      __evolve_time__
+    ],
+    String => %i[
+      __evolve_date__
+      __evolve_time__
+      __expr_part__
+      __mongo_expression__
+      __sort_option__
+      before_type_cast?
+      collectionize
+      reader
+      valid_method_name?
+      writer?
+    ],
+    Symbol => %i[
+      __expr_part__
+      add_to_set
+      all
+      asc
+      ascending
+      avg
+      desc
+      descending
+      elem_match
+      eq
+      exists
+      first
+      gt
+      gte
+      in
+      intersects_line
+      intersects_point
+      intersects_polygon
+      last
+      lt
+      lte
+      max
+      min
+      mod
+      ne
+      near
+      near_sphere
+      nin
+      not
+      push
+      sum
+      with_size
+      with_type
+      within_box
+      within_polygon
+    ],
+    TrueClass => %i[is_a?],
+    Time => %i[
+      __evolve_date__
+      __evolve_time__
+    ],
+    ActiveSupport::TimeWithZone => %i[
+      __evolve_date__
+      __evolve_time__
+      _bson_to_i
+    ],
+    BSON::Decimal128 => %i[
+      __evolve_decimal128__
+    ]
+  }.each_value(&:sort!)
+
+  expected_class_methods = {
+    Object => %i[
+      demongoize
+      evolve
+      re_define_method
+    ],
+    Float => %i[__numeric__],
+    Integer => %i[__numeric__],
+    String => %i[__expr_part__],
+    Symbol => %i[add_key]
+  }.each_value(&:sort!)
+
+  def mongoid_method?(method)
+    method.source_location&.first&.include?('/lib/mongoid/')
+  end
+
+  def added_instance_methods(klass)
+    methods = klass.instance_methods.select { |m| mongoid_method?(klass.instance_method(m)) }
+    methods -= added_instance_methods(Object) unless klass == Object
+    methods.sort
+  end
+
+  def added_class_methods(klass)
+    methods = klass.methods.select { |m| mongoid_method?(klass.method(m)) }
+    methods -= added_instance_methods(Object)
+    methods -= added_class_methods(Object) unless klass == Object
+    methods.sort
+  end
+
+  classes.each do |klass|
+    context klass.name do
+      it 'adds no unexpected instance methods' do
+        expect(added_instance_methods(klass)).to eq(expected_instance_methods[klass] || [])
+      end
+
+      it 'adds no unexpected class methods' do
+        expect(added_class_methods(klass)).to eq(expected_class_methods[klass] || [])
+      end
+    end
+  end
+end