1 files changed, 62 insertions, 0 deletions
diff --git a/spec/scripts/lib/glfm/verify_all_generated_files_are_up_to_date_spec.rb b/spec/scripts/lib/glfm/verify_all_generated_files_are_up_to_date_spec.rb
new file mode 100644
index 00000000000..fca037c9ff3
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+++ b/spec/scripts/lib/glfm/verify_all_generated_files_are_up_to_date_spec.rb
@@ -0,0 +1,62 @@
+# frozen_string_literal: true
+require 'fast_spec_helper'
+require_relative '../../../../scripts/lib/glfm/verify_all_generated_files_are_up_to_date'
+
+# IMPORTANT NOTE: See https://docs.gitlab.com/ee/development/gitlab_flavored_markdown/specification_guide/#verify-all-generated-files-are-up-to-daterb-script
+# for details on the implementation and usage of the `verify_all_generated_files_are_up_to_date.rb` script being tested.
+# This developers guide contains diagrams and documentation of the script,
+# including explanations and examples of all files it reads and writes.
+RSpec.describe Glfm::VerifyAllGeneratedFilesAreUpToDate, '#process' do
+  subject { described_class.new }
+
+  let(:output_path) { described_class::GLFM_SPEC_OUTPUT_PATH }
+  let(:snapshots_path) { described_class::EXAMPLE_SNAPSHOTS_PATH }
+  let(:verify_cmd) { "git status --porcelain #{output_path} #{snapshots_path}" }
+
+  before do
+    # Prevent console output when running tests
+    allow(subject).to receive(:output)
+  end
+
+  context 'when repo is dirty' do
+    before do
+      # Simulate a dirty repo
+      allow(subject).to receive(:run_external_cmd).with(verify_cmd).and_return(" M #{output_path}")
+    end
+
+    it 'raises an error', :unlimited_max_formatted_output_length do
+      expect { subject.process }.to raise_error(/Cannot run.*uncommitted changes.*#{output_path}/m)
+    end
+  end
+
+  context 'when repo is clean' do
+    before do
+      # Mock out all yarn install and script execution
+      allow(subject).to receive(:run_external_cmd).with('yarn install --frozen-lockfile')
+      allow(subject).to receive(:run_external_cmd).with(/update-specification.rb/)
+      allow(subject).to receive(:run_external_cmd).with(/update-example-snapshots.rb/)
+    end
+
+    context 'when all generated files are up to date' do
+      before do
+        # Simulate a clean repo, then simulate no changes to generated files
+        allow(subject).to receive(:run_external_cmd).twice.with(verify_cmd).and_return('', '')
+      end
+
+      it 'does not raise an error', :unlimited_max_formatted_output_length do
+        expect { subject.process }.not_to raise_error
+      end
+    end
+
+    context 'when generated file(s) are not up to date' do
+      before do
+        # Simulate a clean repo, then simulate changes to generated files
+        allow(subject).to receive(:run_external_cmd).twice.with(verify_cmd).and_return('', "M #{snapshots_path}")
+      end
+
+      it 'raises an error', :unlimited_max_formatted_output_length do
+        expect { subject.process }.to raise_error(/following files were modified.*#{snapshots_path}/m)
+      end
+    end
+  end
+end