diff --git a/app/models/fluent_gem.rb b/app/models/fluent_gem.rb
index b48b5a5..8622962 100644
--- a/app/models/fluent_gem.rb
+++ b/app/models/fluent_gem.rb
@@ -17,9 +17,12 @@ module FluentGem
       #       but long living caching causes mismatch with actual status e.g. user install plugin from console (without fluentd-ui)
       #       So our decision is that cache `gem list` in 3 seconds
       Rails.cache.fetch(LIST_CACHE_KEY, expires_in: 3.seconds) do
-        output = `#{gem} list`
-        if $? && $?.exitstatus != 0 # NOTE: $? will be nil on CircleCI, so check $? at first
-          raise GemError, "failed command: `#{gem} list`"
+        last_status = $?
+        output = `#{gem} list 2>&1`
+        # https://github.com/fluent/fluentd-ui/pull/149#issuecomment-71954588
+        # Sometimes, $? wouldn't override with `#{gem} list` but I don't know why..
+        if $? && last_status != $? && $?.exitstatus != 0 # NOTE: $? will be nil on CircleCI, so check $? at first
+          raise GemError, "failed command: `#{gem} list` output: #{output}"
         end
         output.lines.to_a
       end
diff --git a/lib/fluentd-ui.rb b/lib/fluentd-ui.rb
index 2810851..c3772b5 100644
--- a/lib/fluentd-ui.rb
+++ b/lib/fluentd-ui.rb
@@ -21,7 +21,11 @@ module FluentdUI
   end
 
   def self.data_dir
-    dir = ENV["FLUENTD_UI_DATA_DIR"].presence || ENV["HOME"] + "/.fluentd-ui/core_data"
+    if Rails.env.test?
+      dir = Rails.root.join("tmp", "core_data").to_s
+    else
+      dir = ENV["FLUENTD_UI_DATA_DIR"].presence || ENV["HOME"] + "/.fluentd-ui/core_data"
+    end
     FileUtils.mkdir_p(dir) # ensure directory exists
     dir
   end
diff --git a/spec/models/fluentd/agent/local_common_spec.rb b/spec/models/fluentd/agent/local_common_spec.rb
index 8a46cc2..700b1a0 100644
--- a/spec/models/fluentd/agent/local_common_spec.rb
+++ b/spec/models/fluentd/agent/local_common_spec.rb
@@ -47,6 +47,8 @@ describe 'Fluentd::Agent::LocalCommon' do
     CONF
 
     before do
+      # other specs could be write in this dir, so clean that in `before`
+      FileUtils.rm_r daemon.agent.config_backup_dir, force: true
       ::Settings.max_backup_files_count.times do |i|
         backuped_time = now - (i + 1).hours
         FileUtils.touch File.join(daemon.agent.config_backup_dir , "#{backuped_time.strftime('%Y%m%d_%H%M%S')}.conf")
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index c6dee40..d315e94 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -61,4 +61,8 @@ RSpec.configure do |config|
 
   # rspec 2.99
   config.infer_spec_type_from_file_location!
+
+  config.after(:suite) do
+    FileUtils.rm_rf FluentdUI.data_dir
+  end
 end