Add Api::ErrorHandling concern for api/base controller (#29574)

spec/controllers/concerns/api/error_handling_spec.rb

@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe Api::ErrorHandling do
+  before do
+    stub_const('FakeService', Class.new)
+  end
+
+  controller(Api::BaseController) do
+    def failure
+      FakeService.new
+    end
+  end
+
+  describe 'error handling' do
+    before do
+      routes.draw { get 'failure' => 'api/base#failure' }
+    end
+
+    {
+      ActiveRecord::RecordInvalid => 422,
+      ActiveRecord::RecordNotFound => 404,
+      ActiveRecord::RecordNotUnique => 422,
+      Date::Error => 422,
+      HTTP::Error => 503,
+      Mastodon::InvalidParameterError => 400,
+      Mastodon::NotPermittedError => 403,
+      Mastodon::RaceConditionError => 503,
+      Mastodon::RateLimitExceededError => 429,
+      Mastodon::UnexpectedResponseError => 503,
+      Mastodon::ValidationError => 422,
+      OpenSSL::SSL::SSLError => 503,
+      Seahorse::Client::NetworkingError => 503,
+      Stoplight::Error::RedLight => 503,
+    }.each do |error, code|
+      it "Handles error class of #{error}" do
+        allow(FakeService)
+          .to receive(:new)
+          .and_raise(error)
+
+        get :failure
+
+        expect(response)
+          .to have_http_status(code)
+        expect(FakeService)
+          .to have_received(:new)
+      end
+    end
+  end
+end