Add a version sanity check QA smoke test

qa/qa/specs/features/sanity/version_spec.rb

+# frozen_string_literal: true
+
+require 'airborne'
+
+module QA
+  # This test ensures that the version described by the `DEPLOY_VERSION`
+  # environment variable is the version actually running.
+  #
+  # See https://gitlab.com/gitlab-com/gl-infra/delivery/-/issues/1179
+  RSpec.describe 'Version sanity check', :smoke do
+    let(:api_client) { Runtime::API::Client.new(:gitlab) }
+    let(:request) { Runtime::API::Request.new(api_client, '/version') }
+
+    it 'is the specified version' do
+      # The `DEPLOY_VERSION` variable will only be provided for deploys to the
+      # `pre` and `release` environments, which only receive packaged releases.
+      #
+      # For these releases, `deploy_version` will be a package string (e.g.,
+      # `13.1.3-ee.0`), and the reported version will be something like
+      # `13.1.3-ee`, so we only compare the leading SemVer string.
+      #
+      # | Package          | Version        |
+      # | ---------------- | -------------- |
+      # | 13.3.5-ee.0      | 13.3.5-ee      |
+      # | 13.3.0-rc42.ee.0 | 13.3.0-rc42-ee |
+      deploy = Runtime::Env.deploy_version&.gsub(/\A(\d+\.\d+\.\d+).*\z/, '\1')
+
+      skip('No deploy version provided') if deploy.nil? || deploy.empty?
+
+      get request.url
+
+      expect_status(200)
+      expect(json_body).to have_key(:version)
+      expect(json_body[:version]).to start_with(deploy)
+    end
+  end
+end