Add rake task to check cronotab.rb syntax

spec/assets/bad_cronotab.rb

@@ -0,0 +1,12 @@
+# This is an example of a bad cronotab for tests
+
+class TestJob
+  def perform
+    puts 'Test!'
+  end
+end
+
+# This is an error, because you can use `on` options with
+# a period less than 7 days.
+
+Crono.perform(TestJob).every 5.days, on: :sunday

spec/assets/good_cronotab.rb

@@ -0,0 +1,9 @@
+# This is an example of a good cronotab for tests
+
+class TestJob
+  def perform
+    puts 'Test!'
+  end
+end
+
+Crono.perform(TestJob).every 5.seconds

spec/tasks/crono_tasks_spec.rb

@@ -4,11 +4,20 @@ require 'rake'
 load 'tasks/crono_tasks.rake'
 Rake::Task.define_task(:environment)
 
-describe 'crono:clean' do
-  it 'should clean unused tasks from DB' do
-    Crono::CronoJob.create!(job_id: 'used_job')
-    expect(Crono).to receive(:load_cronotab)
-    Rake::Task['crono:clean'].invoke
-    expect(Crono::CronoJob.where(job_id: 'used_job')).not_to exist
+describe 'rake' do
+  describe 'crono:clean' do
+    it 'should clean unused tasks from DB' do
+      Crono::CronoJob.create!(job_id: 'used_job')
+      ENV['CRONOTAB'] = File.expand_path('../../assets/good_cronotab.rb', __FILE__)
+      Rake::Task['crono:clean'].invoke
+      expect(Crono::CronoJob.where(job_id: 'used_job')).not_to exist
+    end
+  end
+
+  describe 'crono:check' do
+    it 'should check cronotab syntax' do
+      ENV['CRONOTAB'] = File.expand_path('../../assets/bad_cronotab.rb', __FILE__)
+      expect { Rake::Task['crono:check'].invoke }.to raise_error
+    end
   end
 end

spec/web_spec.rb

@@ -6,6 +6,7 @@ describe Crono::Web do
   let(:app) { Crono::Web }
 
   before do
+    Crono::CronoJob.destroy_all
     @test_job_id = 'Perform TestJob every 5 seconds'
     @test_job_log = 'All runs ok'
     @test_job = Crono::CronoJob.create!(