Added .active? to Import backends default API for e.g. monitoring checks.

lib/import/base.rb

@@ -3,6 +3,17 @@
 module Import
   class Base
 
+    # Checks if the backend is active.
+    #
+    # @example
+    #  Import::ExampleBackend.active?
+    #  #=> true
+    #
+    # return [Boolean]
+    def self.active?
+      true
+    end
+
     # Checks if the backend is able to get queued by the Scheduler.
     #
     # @example

spec/lib/import/base_spec.rb

@@ -4,6 +4,13 @@ require 'lib/import/import_job_backend_examples'
 RSpec.describe Import::Base do
   it_behaves_like 'ImportJob backend'
 
+  describe '#active?' do
+
+    it 'returns true by default' do
+      expect(described_class.active?).to be true
+    end
+  end
+
   describe '#queueable?' do
 
     it 'returns true by default' do