Introduce helpers (selectors) for anonymise all a subject's records.

.rubocop.yml

@@ -4,9 +4,13 @@ inherit_gem:
 
 AllCops:
   TargetRubyVersion: 3.0
+  NewCops: enable
 
 Layout/LineLength:
   Max: 100
 
 Gemspec/RequiredRubyVersion:
   Enabled: false
+
+RSpec/MultipleExpectations:
+  Enabled: false

lib/anony/anonymisable.rb

@@ -54,6 +54,23 @@ def valid_anonymisation?
         @anonymise_config.valid?
       end
 
+      # Finds the records that relate to a particular subject and runs anonymise on
+      # each of them. If a selector is not defined it will raise an exception.
+      def anonymise_for!(subject, subject_id)
+        anonymise_config.
+          select(subject, subject_id, &:anonymise!)
+      end
+
+      # Checks if a selector has been defined for a given subject.
+      # This is useful for when writing tests to check all models have a valid selector
+      # for a given subject.
+      # @return [Boolean]
+      # @example
+      #   Manager.selector_for?(:user_id)
+      def selector_for?(subject)
+        anonymise_config.selector_for?(subject)
+      end
+
       attr_reader :anonymise_config
     end
 
@@ -74,6 +91,10 @@ def anonymise!
       Result.failed(e)
     end
 
+    def anonymised?
+      anonymised_at.present?
+    end
+
     # @!visibility private
     def self.included(base)
       base.extend(ClassMethods)

lib/anony/model_config.rb

@@ -4,6 +4,7 @@
 
 require_relative "./strategies/destroy"
 require_relative "./strategies/overwrite"
+require_relative "./selectors"
 
 module Anony
   class ModelConfig
@@ -29,6 +30,7 @@ def validate!
     def initialize(model_class, &block)
       @model_class = model_class
       @strategy = UndefinedStrategy.new
+      @selectors_config = nil
       @skip_filter = nil
       instance_exec(&block) if block
     end
@@ -86,6 +88,34 @@ def overwrite(&block)
       @strategy = Strategies::Overwrite.new(@model_class, &block)
     end
 
+    # Define selectors to select records that apply to a particular subject.
+    # This method taks a configuration block that then builds Selectors
+    #
+    # @see Anony::Selectors
+    #
+    # @example
+    #
+    #   anonymise do
+    #     selectors do
+    #       for_subject(:user_id) { |user_id| self.select_for_user(user_id) }
+    #     end
+    #   end
+    #
+    #   ModelName.anonymise_for!(:user_id, "user_1234")
+    def selectors(&block)
+      @selectors_config = Selectors.new(@model_class, &block)
+    end
+
+    def select(subject, subject_id, &block)
+      @selectors_config.select(subject, subject_id, &block)
+    end
+
+    def selector_for?(subject)
+      return nil if @selectors_config.nil?
+
+      @selectors_config.selectors[subject].present?
+    end
+
     # Prevent any anonymisation strategy being applied when the provided block evaluates
     # to true. The block is executed in the model context.
     #

lib/anony/selector_not_found_exception.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+module Anony
+  class SelectorNotFoundException < StandardError
+    def initialize(selector, model_name)
+      super("Selector for #{selector} not found. Make sure you have one defined in #{model_name}")
+    end
+  end
+end

lib/anony/selectors.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+require_relative "./selector_not_found_exception"
+
+module Anony
+  class Selectors
+    def initialize(model_class, &block)
+      @model_class = model_class
+      @selectors = {}
+      instance_exec(&block) if block
+    end
+
+    attr_reader :selectors
+
+    def for_subject(subject, &block)
+      selectors[subject] = block
+    end
+
+    def select(subject, subject_id, &block)
+      selector = selectors[subject]
+      raise SelectorNotFoundException.new(subject.to_s, @model_class.name) if selector.nil?
+
+      matching = @model_class.instance_exec(subject_id, &selector)
+      matching.map(&block)
+    end
+  end
+end

spec/anony/activerecord_spec.rb

@@ -34,9 +34,9 @@
   # rubocop:disable RSpec/ExampleLength
   it "applies the correct changes to each column" do
     expect { instance.anonymise! }.
-      to change(instance, :first_name).to(/[\h\-]{36}/).
+      to change(instance, :first_name).to(/[\h-]{36}/).
       and change(instance, :last_name).to(nil).
-      and change(instance, :email_address).to(/[\h\-]@example.com/).
+      and change(instance, :email_address).to(/[\h-]@example.com/).
       and change(instance, :phone_number).to("+1 617 555 1294").
       and change(instance, :company_name).to("anonymised-Microsoft").
       and change(instance, :onboarded_at).to be_within(1).of(Time.now)

spec/anony/anonymisable_spec.rb

@@ -15,9 +15,24 @@ def self.call(*_)
       Class.new(ActiveRecord::Base) do
         include Anony::Anonymisable
 
+        # give this anon class a name
+        def self.name
+          "Employee"
+        end
+
         self.table_name = :employees
 
         anonymise do
+          selectors do
+            for_subject(:first_name) do |first_name|
+              where(first_name: first_name)
+            end
+
+            for_subject(:company_name) do |company_name|
+              where(company_name: company_name)
+            end
+          end
+
           overwrite do
             ignore :id
             with_strategy StubAnoynmiser, :company_name
@@ -38,7 +53,35 @@ def some_instance_method?
     end
 
     let(:model) do
-      klass.new(first_name: "abc", last_name: "foo")
+      klass.create!(first_name: "abc", last_name: "foo", company_name: "alpha")
+    end
+
+    describe ".anonymise_for!" do
+      let!(:model_b) do
+        klass.create!(first_name: "matt", last_name: "brown", company_name: "alpha")
+      end
+
+      context "selector not found" do
+        it "raises an error" do
+          expect do
+            klass.anonymise_for!(:random, "hello")
+          end.to raise_error(Anony::SelectorNotFoundException)
+        end
+      end
+
+      context "single record" do
+        it "changes the matching record" do
+          klass.anonymise_for!(:first_name, model.first_name)
+          expect(model.reload.anonymised?).to eq(true)
+          expect(model_b.reload.anonymised?).to eq(false)
+        end
+      end
+
+      it "anonymises only the matching models: company_name" do
+        klass.anonymise_for!(:company_name, model.company_name)
+        expect(model.reload.anonymised?).to be(true)
+        expect(model_b.reload.anonymised?).to be(true)
+      end
     end
 
     describe "#anonymise!" do

spec/anony/field_level_strategies_spec.rb

@@ -82,7 +82,7 @@
 
     let(:value) { "old value" }
 
-    it { is_expected.to match(/^[0-9a-f\-]+@example.com$/) }
+    it { is_expected.to match(/^[0-9a-f-]+@example.com$/) }
   end
 
   describe ":phone_number strategy" do