Default to a single worker with default settings when no config is provided

In this way, someone just starting Solid Queue will have something that dispatches
and processes jobs without having to worry about a configuration file.

Also: make the default queues (all queues) explicit.

Author: rosa

lib/solid_queue/configuration.rb

@@ -3,14 +3,15 @@
 module SolidQueue
   class Configuration
     WORKER_DEFAULTS = {
+      queues: "*",
       threads: 5,
       processes: 1,
       polling_interval: 0.1
     }
 
     DISPATCHER_DEFAULTS = {
       batch_size: 500,
-      polling_interval: 5,
+      polling_interval: 1,
       concurrency_maintenance_interval: 600
     }
 
@@ -61,7 +62,7 @@ def config_from(file_or_hash, env: Rails.env)
       end
 
       def workers_options
-        @workers_options ||= (raw_config[:workers] || {}).map { |options| options.dup.symbolize_keys }
+        @workers_options ||= (raw_config[:workers] || [ WORKER_DEFAULTS ]).map { |options| options.dup.symbolize_keys }
       end
 
       def dispatcher_options

test/unit/configuration_test.rb

@@ -1,6 +1,17 @@
 require "test_helper"
 
 class ConfigurationTest < ActiveSupport::TestCase
+  test "default configuration to process all queues and dispatch" do
+    configuration = SolidQueue::Configuration.new(mode: :all, load_from: {})
+    assert_equal 2, configuration.processes.count
+
+    assert_equal 1, configuration.workers.count
+    assert configuration.dispatcher.present?
+
+    assert_equal [ "*" ], configuration.workers.first.queues
+    assert_equal SolidQueue::Configuration::DISPATCHER_DEFAULTS[:batch_size], configuration.dispatcher.batch_size
+  end
+
   test "read configuration from default file" do
     configuration = SolidQueue::Configuration.new(mode: :all)
     assert 3, configuration.processes.count