Testing random assignment behaviour

.github/workflows/minitest.yml

@@ -20,11 +20,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ci_node_index: [
-          "test/unit/lib test/unit/app/helpers test/unit/app/presenters test/unit/app/validators test/unit/app/workers test/views",
-          "test/unit/app/models test/unit/app/services test/unit/app/uploaders test/unit/*_test.rb",
-          "test/functional test/components test/integration"
-        ]
+        ci_node_total: [3]
+        ci_node_index: [0, 1, 2]
     steps:
       - name: Setup MySQL
         id: setup-mysql
@@ -68,9 +65,15 @@ jobs:
           TEST_DATABASE_URL: ${{ steps.setup-mysql.outputs.db-url }}
         run: bundle exec rails db:setup
 
+      - name: Make bin/minitest-ci executable
+        run: chmod +x ./bin/minitest-ci
+
       - name: Run Minitest
         env:
           RAILS_ENV: test
           GOVUK_CONTENT_SCHEMAS_PATH: vendor/publishing-api/content_schemas
           TEST_DATABASE_URL: ${{ steps.setup-mysql.outputs.db-url }}
-        run: bundle exec rails test ${{ matrix.ci_node_index }}
+          CI_NODE_TOTAL: ${{ matrix.ci_node_total }}
+          CI_NODE_INDEX: ${{ matrix.ci_node_index }}
+        run: |
+          ./bin/minitest-ci

bin/minitest-ci

@@ -0,0 +1,12 @@
+#!/usr/bin/env ruby
+
+tests = Dir["test/**/*_test.rb"].
+  sort.
+  # Add randomization seed based on SHA of each commit
+  shuffle(random: Random.new(ENV['GITHUB_SHA'].to_i(16))).
+  select.
+  with_index do |el, i|
+    i % ENV["CI_NODE_TOTAL"].to_i == ENV["CI_NODE_INDEX"].to_i
+  end
+
+exec "bundle exec rails test #{tests.join(" ")}"

test/unit/inflections_test.rb

@@ -15,7 +15,7 @@ class InflectionsTest < ActiveSupport::TestCase
 
   test "Secretaries of things are plurlised correctly" do
     assert_equal "Foreign Secretaries", "Foreign Secretary".pluralize
-    assert_equal "Cabinet Secretaries", "Cabinet Secretary".pluralize
+    assert_equal "Cabinet Secies", "Cabinet Secretary".pluralize
   end
 
   test "Call for evidence pluralises correctly" do