Auto-sync track GitHub maintained/unmaintained topic

app/commands/github/team_member/create.rb

@@ -5,7 +5,10 @@ class Github::TeamMember::Create
 
   def call
     user.github_team_memberships.find_or_create_by!(team_name:).tap do |team_member|
-      User::UpdateMaintainer.(user) if team_member.previously_new_record? && team_member.track_id
+      next unless team_member.previously_new_record? && team_member.track_id
+
+      User::UpdateMaintainer.(user)
+      Track::UpdateGithubMaintenanceStatus.defer(team_member.track)
     end
   end
 end

app/commands/github/team_member/destroy.rb

@@ -5,6 +5,9 @@ class Github::TeamMember::Destroy
 
   def call
     team_member.delete
-    User::UpdateMaintainer.(team_member.user) if team_member.track_id
+    return unless team_member.track_id
+
+    User::UpdateMaintainer.(team_member.user)
+    Track::UpdateGithubMaintenanceStatus.defer(team_member.track)
   end
 end

app/commands/track/update_github_maintenance_status.rb

@@ -0,0 +1,43 @@
+# Keeps a track repo's GitHub `maintained`/`unmaintained` topic in sync with
+# whether the track has any maintainers on its GitHub team. Those topics drive
+# the automated "this repo is unmaintained" PR comments (see the
+# ping-cross-track-maintainers-team workflow), so promoting a track the moment
+# it gains a maintainer silences them without any manual intervention.
+#
+# We only ever toggle the plain `maintained` <-> `unmaintained` pair. The
+# nuanced categories (`wip-track`, `maintained-autonomous`, `maintained-solitary`)
+# are deliberate admin choices, so we leave them untouched.
+class Track::UpdateGithubMaintenanceStatus
+  include Mandate
+
+  initialize_with :track
+
+  def call
+    return if Rails.env.development?
+    return unless new_topic
+
+    Exercism.octokit_client.replace_all_topics(repo, (current_topics - TOGGLEABLE) + [new_topic])
+  end
+
+  private
+  memoize
+  def new_topic
+    if maintained?
+      MAINTAINED if current_topics.include?(UNMAINTAINED)
+    elsif current_topics.include?(MAINTAINED)
+      UNMAINTAINED
+    end
+  end
+
+  def maintained? = track.github_team_members.exists?
+
+  memoize
+  def current_topics = Exercism.octokit_client.topics(repo).names
+
+  def repo = "exercism/#{track.slug}"
+
+  MAINTAINED = "maintained".freeze
+  UNMAINTAINED = "unmaintained".freeze
+  TOGGLEABLE = [MAINTAINED, UNMAINTAINED].freeze
+  private_constant :MAINTAINED, :UNMAINTAINED, :TOGGLEABLE
+end

test/commands/github/team_member/create_test.rb

@@ -13,13 +13,14 @@ class Github::TeamMember::CreateTest < ActiveSupport::TestCase
     assert_equal team_name, team_name_member.team_name
   end
 
-  test "update maintainer role" do
+  test "update maintainer role and sync maintenance status" do
     github_uid = '137131'
     team_name = 'fsharp'
 
-    create(:track, slug: team_name)
+    track = create(:track, slug: team_name)
     user = create(:user, uid: github_uid)
     User::UpdateMaintainer.expects(:call).with(user).once
+    Track::UpdateGithubMaintenanceStatus.expects(:defer).with(track).once
 
     team_name_member = Github::TeamMember::Create.(user, team_name)
 
@@ -34,6 +35,7 @@ class Github::TeamMember::CreateTest < ActiveSupport::TestCase
     user = create(:user, uid: github_uid)
 
     User::UpdateMaintainer.expects(:call).with(user).never
+    Track::UpdateGithubMaintenanceStatus.expects(:defer).never
 
     Github::TeamMember::Create.(user, team_name)
   end
@@ -45,6 +47,7 @@ class Github::TeamMember::CreateTest < ActiveSupport::TestCase
     create(:github_team_member, team_name:, user:)
 
     User::UpdateMaintainer.expects(:call).with(user).never
+    Track::UpdateGithubMaintenanceStatus.expects(:defer).never
 
     Github::TeamMember::Create.(user, team_name)
   end

test/commands/github/team_member/destroy_test.rb

@@ -13,15 +13,16 @@ class Github::TeamMember::DestroyTest < ActiveSupport::TestCase
     refute Github::TeamMember.where(user:, team_name:).exists?
   end
 
-  test "update maintainer role when track team" do
+  test "update maintainer role and sync maintenance status when track team" do
     github_uid = '137131'
     team_name = 'fsharp'
 
     user = create(:user, uid: github_uid)
-    create(:track, slug: team_name)
+    track = create(:track, slug: team_name)
     team_member = create(:github_team_member, team_name:, user:)
 
     User::UpdateMaintainer.expects(:call).with(user).once
+    Track::UpdateGithubMaintenanceStatus.expects(:defer).with(track).once
 
     Github::TeamMember::Destroy.(team_member)
   end
@@ -34,6 +35,7 @@ class Github::TeamMember::DestroyTest < ActiveSupport::TestCase
     team_member = create(:github_team_member, team_name:, user:)
 
     User::UpdateMaintainer.expects(:call).never
+    Track::UpdateGithubMaintenanceStatus.expects(:defer).never
 
     Github::TeamMember::Destroy.(team_member)
   end

test/commands/track/update_github_maintenance_status_test.rb

@@ -0,0 +1,79 @@
+require "test_helper"
+
+class Track::UpdateGithubMaintenanceStatusTest < ActiveSupport::TestCase
+  test "promotes unmaintained repo to maintained when track has a maintainer" do
+    track = create(:track, slug: 'fortran')
+    create(:github_team_member, team_name: 'fortran')
+
+    stub_topics('fortran', %w[exercism-track community-contributions-paused unmaintained])
+    put = stub_replace_topics('fortran', %w[exercism-track community-contributions-paused maintained])
+
+    Track::UpdateGithubMaintenanceStatus.(track)
+
+    assert_requested put
+  end
+
+  test "demotes maintained repo to unmaintained when track has no maintainers" do
+    track = create(:track, slug: 'fortran')
+
+    stub_topics('fortran', %w[exercism-track maintained])
+    put = stub_replace_topics('fortran', %w[exercism-track unmaintained])
+
+    Track::UpdateGithubMaintenanceStatus.(track)
+
+    assert_requested put
+  end
+
+  test "does nothing when already maintained and has a maintainer" do
+    track = create(:track, slug: 'fortran')
+    create(:github_team_member, team_name: 'fortran')
+
+    stub_topics('fortran', %w[exercism-track maintained])
+
+    Track::UpdateGithubMaintenanceStatus.(track)
+    # No PUT stubbed, so WebMock raises if replace_all_topics is called
+  end
+
+  test "does nothing when already unmaintained and has no maintainers" do
+    track = create(:track, slug: 'fortran')
+
+    stub_topics('fortran', %w[exercism-track unmaintained])
+
+    Track::UpdateGithubMaintenanceStatus.(track)
+  end
+
+  test "leaves nuanced maintained categories untouched" do
+    track = create(:track, slug: 'fortran')
+    # No team members, but the track is deliberately labelled solitary/autonomous
+    %w[maintained-solitary maintained-autonomous wip-track].each do |category|
+      stub_topics('fortran', ['exercism-track', category])
+
+      Track::UpdateGithubMaintenanceStatus.(track)
+      # No PUT stubbed for any of these, so WebMock raises on a write
+    end
+  end
+
+  test "does nothing in development" do
+    track = create(:track, slug: 'fortran')
+    Rails.env.stubs(:development?).returns(true)
+
+    Track::UpdateGithubMaintenanceStatus.(track)
+    # No API calls stubbed - WebMock raises if any are made
+  end
+
+  private
+  def stub_topics(slug, names)
+    stub_request(:get, %r{https://api\.github\.com/repos/exercism/#{slug}/topics}).
+      to_return(
+        status: 200,
+        body: { names: }.to_json,
+        headers: { 'Content-Type': 'application/json' }
+      )
+  end
+
+  def stub_replace_topics(slug, expected_names)
+    stub_request(:put, "https://api.github.com/repos/exercism/#{slug}/topics").
+      with { |request| JSON.parse(request.body)["names"] == expected_names }.
+      to_return(status: 200, body: { names: expected_names }.to_json, headers: { 'Content-Type': 'application/json' })
+  end
+end