Add metrics for nested packs

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    modularization_statistics (1.34.0)
+    modularization_statistics (1.35.0)
       code_ownership
       code_teams
       dogapi

lib/modularization_statistics/private/datadog_reporter.rb

@@ -8,6 +8,7 @@
 require 'modularization_statistics/private/metrics/protection_usage'
 require 'modularization_statistics/private/metrics/packages'
 require 'modularization_statistics/private/metrics/packages_by_team'
+require 'modularization_statistics/private/metrics/nested_packs'
 
 module ModularizationStatistics
   module Private
@@ -26,7 +27,8 @@ def self.get_metrics(source_code_files:, app_name:)
         [
           *Metrics::Files.get_metrics(source_code_files, app_name),
           *Metrics::Packages.get_package_metrics(packages, app_name),
-          *Metrics::PackagesByTeam.get_package_metrics_by_team(packages, app_name)
+          *Metrics::PackagesByTeam.get_package_metrics_by_team(packages, app_name),
+          *Metrics::NestedPacks.get_nested_package_metrics(packages, app_name)
         ]
       end
 

lib/modularization_statistics/private/metrics/nested_packs.rb

@@ -0,0 +1,116 @@
+# typed: strict
+# frozen_string_literal: true
+
+module ModularizationStatistics
+  module Private
+    module Metrics
+      class NestedPacks
+        extend T::Sig
+
+        class PackGroup < T::Struct
+          extend T::Sig
+
+          const :name, String
+          const :root, ParsePackwerk::Package
+          const :members, T::Array[ParsePackwerk::Package]
+
+          sig { params(packages: T::Array[ParsePackwerk::Package]).returns(T::Array[PackGroup]) }
+          def self.all_from(packages)
+            packs_by_group = {}
+
+            packages.each do |package|
+              # For a child pack, package.directory is `packs/fruits/apples` (i.e. the directory of the package.yml file).
+              # The package.directory.dirname is therefore `packs/fruits`.
+              # For a standalone pack, package.directory.dirname is `packs`
+              # A pack with no parent is in a pack group of its own name
+              root = ParsePackwerk.find(package.directory.dirname.to_s) || package
+              # Mark the parent pack and child pack as being in the pack group of the parent
+              packs_by_group[root.name] ||= { root: root, members: [] }
+              packs_by_group[root.name][:members] << package
+            end
+
+            packs_by_group.map do |name, pack_data|
+              PackGroup.new(
+                name: name,
+                root: pack_data[:root],
+                members: pack_data[:members],
+              )
+            end
+          end
+
+          sig { returns(Integer) }
+          def children_pack_count
+            members.count do |package|
+              package.name != root.name
+            end
+          end
+
+          sig { returns(T::Boolean) }
+          def has_parent?
+            children_pack_count > 0
+          end
+
+          sig { returns(T::Array[ParsePackwerk::Violation]) }
+          def cross_group_violations
+            all_violations = members.flat_map do |member|
+              ParsePackwerk::DeprecatedReferences.for(member).violations
+            end
+
+            all_violations.select do |violation|
+              !members.map(&:name).include?(violation.to_package_name)
+            end
+          end
+        end
+
+        sig do
+          params(
+            packages: T::Array[ParsePackwerk::Package],
+            app_name: String
+          ).returns(T::Array[GaugeMetric])
+        end
+        def self.get_nested_package_metrics(packages, app_name)
+          all_metrics = []
+          app_level_tag = Tag.for('app', app_name)
+          package_tags = T.let([app_level_tag], T::Array[Tag])
+
+          pack_groups = PackGroup.all_from(packages)
+          all_pack_groups_count = pack_groups.count
+          child_pack_count = pack_groups.sum(&:children_pack_count)
+          parent_pack_count = pack_groups.count(&:has_parent?)
+          all_cross_pack_group_violations = pack_groups.flat_map(&:cross_group_violations)
+
+          all_metrics << GaugeMetric.for('all_pack_groups.count', all_pack_groups_count, package_tags)
+          all_metrics << GaugeMetric.for('child_packs.count', child_pack_count, package_tags)
+          all_metrics << GaugeMetric.for('parent_packs.count', parent_pack_count, package_tags)
+          all_metrics << GaugeMetric.for('all_pack_groups.privacy_violations.count', Metrics.file_count(all_cross_pack_group_violations.select(&:privacy?)), package_tags)
+          all_metrics << GaugeMetric.for('all_pack_groups.dependency_violations.count', Metrics.file_count(all_cross_pack_group_violations.select(&:dependency?)), package_tags)
+
+          packs_by_group = {}
+          pack_groups.each do |pack_group|
+            pack_group.members.each do |member|
+              packs_by_group[member.name] = pack_group.name
+            end
+          end
+
+          pack_groups.each do |from_pack_group|
+            violations_by_to_pack_group = from_pack_group.cross_group_violations.group_by do |violation|
+              packs_by_group[violation.to_package_name]
+            end
+            violations_by_to_pack_group.each do |to_pack_group_name, violations|
+              tags = [
+                *package_tags,
+                Tag.for('pack_group', Metrics.humanized_package_name(from_pack_group.name)),
+                Tag.for('to_pack_group', Metrics.humanized_package_name(to_pack_group_name)),
+              ]
+
+              all_metrics << GaugeMetric.for('by_pack_group.outbound_dependency_violations.per_pack_group.count', Metrics.file_count(violations.select(&:dependency?)), tags)
+              all_metrics << GaugeMetric.for('by_pack_group.outbound_privacy_violations.per_pack_group.count', Metrics.file_count(violations.select(&:privacy?)), tags)
+            end
+          end
+
+          all_metrics
+        end
+      end
+    end
+  end
+end

modularization_statistics.gemspec

@@ -1,6 +1,6 @@
 Gem::Specification.new do |spec|
   spec.name          = 'modularization_statistics'
-  spec.version       = '1.34.0'
+  spec.version       = '1.35.0'
   spec.authors       = ['Gusto Engineers']
   spec.email         = ['dev@gusto.com']
 

spec/modularization_statistics_spec.rb

@@ -3,9 +3,7 @@
 module ModularizationStatistics # rubocop:disable RSpec/DescribedClassModuleWrapping
   RSpec.describe ModularizationStatistics do
     before do
-      # We clear the packwerk cache so that we can test new sets of packages each time
-      # We should probably think of a better design to accomplish this!
-      ParsePackwerk.instance_variable_set(:@packages_by_name, nil)
+      ParsePackwerk.bust_cache!
     end
 
     describe 'ModularizationStatistics.report_to_datadog!' do
@@ -58,13 +56,10 @@ module ModularizationStatistics # rubocop:disable RSpec/DescribedClassModuleWrap
       end
 
       context 'in empty app' do
-        # This number will increase whenever a new protection is added
         before do
           write_file('empty_file.rb')
         end
 
-        it { expect(metrics.count).to eq 35 }
-
         it 'emits the right metrics' do
           expect(metrics).to include_metric GaugeMetric.for('component_files.by_team', 0, Tags.for(['team:Unknown', 'app:MyApp']))
           expect(metrics).to include_metric GaugeMetric.for('packaged_files.by_team', 0, Tags.for(['team:Unknown', 'app:MyApp']))
@@ -1011,6 +1006,118 @@ module ModularizationStatistics # rubocop:disable RSpec/DescribedClassModuleWrap
           expect(metrics).to include_metric GaugeMetric.for('by_team.notify_on_new_violations.count', 1, Tags.for(['team:Unknown', 'app:MyApp']))
         end
       end
+
+      context 'in an app with nested packs' do
+        before do
+          write_package_yml('.')
+          write_package_yml('packs/fruits')
+          write_package_yml('packs/fruits/apples')
+          write_package_yml('packs/fruits/pears')
+
+          write_package_yml('packs/vegetables')
+          write_package_yml('packs/vegetables/broccoli')
+
+          write_package_yml('packs/peanuts')
+          write_package_yml('packs/cashews')
+
+          # Represents TWO privacy and TWO dependency violations across pack groups
+          write_file('deprecated_references.yml', <<~CONTENTS)
+            # This file contains a list of dependencies that are not part of the long term plan for ..
+            # We should generally work to reduce this list, but not at the expense of actually getting work done.
+            #
+            # You can regenerate this file using the following command:
+            #
+            # bundle exec packwerk update-deprecations .
+            ---
+            packs/fruits:
+              "FruitsConstant":
+                violations:
+                - dependency
+                - privacy
+                files:
+                - some_file1.rb
+                - some_file2.rb
+          CONTENTS
+
+          # Represents ONE privacy and ZERO dependency violations across pack groups
+          write_file('packs/fruits/deprecated_references.yml', <<~CONTENTS)
+            # This file contains a list of dependencies that are not part of the long term plan for ..
+            # We should generally work to reduce this list, but not at the expense of actually getting work done.
+            #
+            # You can regenerate this file using the following command:
+            #
+            # bundle exec packwerk update-deprecations .
+            ---
+            packs/fruits/apples:
+              "ApplesConstant":
+                violations:
+                - dependency
+                - privacy
+                files:
+                - some_file1.rb
+                - some_file2.rb
+            packs/peanuts:
+              "PeanutsConstant":
+                violations:
+                - privacy
+                files:
+                - some_file1.rb
+          CONTENTS
+
+          # Represents ZERO violations across pack groups
+          write_file('packs/fruits/apples/deprecated_references.yml', <<~CONTENTS)
+            # This file contains a list of dependencies that are not part of the long term plan for ..
+            # We should generally work to reduce this list, but not at the expense of actually getting work done.
+            #
+            # You can regenerate this file using the following command:
+            #
+            # bundle exec packwerk update-deprecations .
+            ---
+            packs/fruits:
+              "FruitsConstant":
+                violations:
+                - dependency
+                - privacy
+                files:
+                - packs/fruits/apples/some_file1.rb
+                - packs/fruits/apples/some_file2.rb
+                - packs/fruits/apples/some_file3.rb
+                - packs/fruits/apples/some_file4.rb
+            packs/fruits/pears:
+              "PearsConstant":
+                violations:
+                - dependency
+                - privacy
+                files:
+                - packs/fruits/apples/some_file1.rb
+                - packs/fruits/apples/some_file2.rb
+                - packs/fruits/apples/some_file3.rb
+                - packs/fruits/apples/some_file4.rb
+            packs/peanuts:
+              "PeanutsConstant":
+                violations:
+                - dependency
+                files:
+                - packs/fruits/apples/some_file1.rb
+          CONTENTS
+        end
+
+        it 'emits the right metrics' do
+          expect(metrics).to include_metric GaugeMetric.for('all_packages.count', 8, Tags.for(['app:MyApp']))
+          expect(metrics).to include_metric GaugeMetric.for('all_pack_groups.count', 5, Tags.for(['app:MyApp']))
+          expect(metrics).to include_metric GaugeMetric.for('child_packs.count', 3, Tags.for(['app:MyApp']))
+          expect(metrics).to include_metric GaugeMetric.for('parent_packs.count', 2, Tags.for(['app:MyApp']))
+
+          # Notice that this does not use a tag to specify the pack group -- the metric itself only sends information about cross-pack group violations
+          expect(metrics).to include_metric GaugeMetric.for('all_pack_groups.privacy_violations.count', 3, Tags.for(['app:MyApp']))
+          expect(metrics).to include_metric GaugeMetric.for('all_pack_groups.dependency_violations.count', 3, Tags.for(['app:MyApp']))
+
+          # This does have a tag for pack group, but the metric itself also only sends information about cross-pack group violations.
+          expect(metrics).to include_metric GaugeMetric.for('by_pack_group.outbound_dependency_violations.per_pack_group.count', 2, Tags.for(['app:MyApp', 'pack_group:root', 'to_pack_group:packs/fruits']))
+          expect(metrics).to include_metric GaugeMetric.for('by_pack_group.outbound_privacy_violations.per_pack_group.count', 2, Tags.for(['app:MyApp', 'pack_group:root', 'to_pack_group:packs/fruits']))
+          expect(metrics).to include_metric GaugeMetric.for('by_pack_group.outbound_dependency_violations.per_pack_group.count', 1, Tags.for(['app:MyApp', 'pack_group:packs/fruits', 'to_pack_group:packs/peanuts']))
+        end
+      end
     end
   end
 end

spec/spec_helper.rb

@@ -95,3 +95,42 @@ def sorbet_double(stubbed_class, attr_map = {})
     end
   end
 end
+
+def write_package_yml(
+  pack_name,
+  dependencies: [],
+  enforce_dependencies: true,
+  enforce_privacy: true,
+  protections: {},
+  global_namespaces: [],
+  visible_to: [],
+  owner: nil
+)
+  defaults = {
+    'prevent_this_package_from_violating_its_stated_dependencies' => 'fail_on_new',
+    'prevent_other_packages_from_using_this_packages_internals' => 'fail_on_new',
+    'prevent_this_package_from_exposing_an_untyped_api' => 'fail_on_new',
+    'prevent_this_package_from_creating_other_namespaces' => 'fail_on_new',
+    'prevent_other_packages_from_using_this_package_without_explicit_visibility' => 'fail_never',
+  }
+  protections_with_defaults = defaults.merge(protections)
+  metadata = { 'protections' => protections_with_defaults }
+
+  if owner
+    metadata.merge({ 'owner' => owner })
+  end
+
+  if global_namespaces
+    metadata.merge({ 'global_namespaces' => global_namespaces })
+  end
+
+  package = ParsePackwerk::Package.new(
+    name: pack_name,
+    dependencies: dependencies,
+    enforce_dependencies: enforce_dependencies,
+    enforce_privacy: enforce_privacy,
+    metadata: metadata
+  )
+
+  ParsePackwerk.write_package_yml!(package)
+end