don't fail when the cli didn't return a correct task list

this can e.g. happen when the CLI is badly set up

definitions/features/pulpcore.rb

@@ -21,11 +21,13 @@ def cli_available?
   end
 
   def cli(args)
-    parse_json(execute("pulp --format json #{args}"))
+    parse_json(execute!("pulp --format json #{args}"))
   end
 
   def running_tasks
     cli('task list --state-in running --state-in canceling')
+  rescue ForemanMaintain::Error::ExecutionError
+    []
   end
 
   def wait_for_tasks(spinner, timeout_for_tasks_status = TIMEOUT_FOR_TASKS_STATUS)

test/definitions/features/pulpcore_test.rb

@@ -5,6 +5,35 @@
 
   subject { Features::Pulpcore.new }
 
+  describe '.cli' do
+    it 'returns hash result when getting JSON reply' do
+      subject.expects(:execute!).with('pulp --format json status').returns('{"versions": []}')
+      expected = { 'versions' => [] }
+      assert_equal expected, subject.cli('status')
+    end
+
+    it 'passes on ExecutionError' do
+      subject.expects(:execute!).with('pulp --format json status').raises(ForemanMaintain::Error::ExecutionError.new('', 1, '', ''))
+      assert_raises(ForemanMaintain::Error::ExecutionError) do
+        subject.cli('status')
+      end
+    end
+  end
+
+  describe '.running_tasks' do
+    it 'returns an empty list when there are no tasks' do
+      subject.expects(:execute!).with('pulp --format json task list --state-in running --state-in canceling').returns('[]')
+      assert_empty subject.running_tasks
+    end
+
+    it 'returns an empty list when pulp cli failed' do
+      subject.expects(:execute!).with('pulp --format json task list --state-in running --state-in canceling').raises(ForemanMaintain::Error::ExecutionError.new(
+        '', 1, '', ''
+      ))
+      assert_empty subject.running_tasks
+    end
+  end
+
   describe '.cli_available?' do
     it 'recognizes server with CLI' do
       File.expects(:exist?).with('/etc/pulp/cli.toml').returns(true)