diff --git a/Rakefile b/Rakefile
index b386599b..2c00efd6 100644
--- a/Rakefile
+++ b/Rakefile
@@ -7,7 +7,7 @@ require 'coveralls/rake/task'
 # Test unit
 Rake::TestTask.new do |t|
   t.libs << 'test'
-  t.test_files = FileList['test/test*.rb']
+  t.test_files = FileList['test/**/test*.rb']
   t.verbose = true
 end
 
diff --git a/test/excelx/cell/test_base.rb b/test/excelx/cell/test_base.rb
index 6a5e4990..17c83beb 100644
--- a/test/excelx/cell/test_base.rb
+++ b/test/excelx/cell/test_base.rb
@@ -1,5 +1,4 @@
-require 'roo/excelx/cell/base'
-require 'roo/link'
+require 'test_helper'
 
 class TestRooExcelxCellBase < Minitest::Test
   def base
diff --git a/test/excelx/cell/test_boolean.rb b/test/excelx/cell/test_boolean.rb
index f4731eba..5087db2e 100644
--- a/test/excelx/cell/test_boolean.rb
+++ b/test/excelx/cell/test_boolean.rb
@@ -1,6 +1,4 @@
-require 'roo/excelx/cell/base'
-require 'roo/excelx/cell/boolean'
-require 'roo/link'
+require 'test_helper'
 
 class TestRooExcelxCellNumber < Minitest::Test
   def boolean
diff --git a/test/excelx/cell/test_date.rb b/test/excelx/cell/test_date.rb
index f37f59e1..7bd046be 100644
--- a/test/excelx/cell/test_date.rb
+++ b/test/excelx/cell/test_date.rb
@@ -1,9 +1,4 @@
-require 'date'
-require 'roo/excelx/cell/base'
-require 'roo/excelx/cell/datetime'
-require 'roo/excelx/cell/date'
-require 'roo/link'
-require 'pry'
+require 'test_helper'
 
 class TestRooExcelxCellDate < Minitest::Test
   def date_cell
diff --git a/test/excelx/cell/test_datetime.rb b/test/excelx/cell/test_datetime.rb
index 74c82a7c..425830bd 100644
--- a/test/excelx/cell/test_datetime.rb
+++ b/test/excelx/cell/test_datetime.rb
@@ -1,7 +1,4 @@
-require 'date'
-require 'roo/excelx/cell/base'
-require 'roo/excelx/cell/datetime'
-require 'roo/link'
+require 'test_helper'
 
 class TestRooExcelxCellDateTime < Minitest::Test
   def test_cell_value_is_datetime
diff --git a/test/excelx/cell/test_empty.rb b/test/excelx/cell/test_empty.rb
index 045274be..82637145 100644
--- a/test/excelx/cell/test_empty.rb
+++ b/test/excelx/cell/test_empty.rb
@@ -1,5 +1,4 @@
-require 'roo/excelx/cell/base'
-require 'roo/excelx/cell/empty'
+require 'test_helper'
 
 class TestRooExcelxCellEmpty < Minitest::Test
   def empty
diff --git a/test/excelx/cell/test_number.rb b/test/excelx/cell/test_number.rb
index ad75d386..84277911 100644
--- a/test/excelx/cell/test_number.rb
+++ b/test/excelx/cell/test_number.rb
@@ -1,6 +1,4 @@
-require 'roo/excelx/cell/base'
-require 'roo/excelx/cell/number'
-require 'roo/link'
+require 'test_helper'
 
 class TestRooExcelxCellNumber < Minitest::Test
   def number
@@ -35,7 +33,7 @@ def test_formats_with_negative_numbers
   end
 
   def test_numbers_with_cell_errors
-    Excels::ERROR_VALUES.each do |error|
+    Roo::Excelx::ERROR_VALUES.each do |error|
       cell = Roo::Excelx::Cell::Number.new error, nil, ['General'], nil, nil, nil
       assert_equal error, cell.value
       assert_equal error, cell.formatted_value
diff --git a/test/excelx/cell/test_string.rb b/test/excelx/cell/test_string.rb
index 2ace5fe6..f1c848fb 100644
--- a/test/excelx/cell/test_string.rb
+++ b/test/excelx/cell/test_string.rb
@@ -1,6 +1,4 @@
-require 'roo/excelx/cell/base'
-require 'roo/excelx/cell/string'
-require 'roo/link'
+require 'test_helper'
 
 class TestRooExcelxCellString < Minitest::Test
   def string
diff --git a/test/excelx/cell/test_time.rb b/test/excelx/cell/test_time.rb
index 5fbff0a3..9fbc5c26 100644
--- a/test/excelx/cell/test_time.rb
+++ b/test/excelx/cell/test_time.rb
@@ -1,7 +1,4 @@
-require 'roo/excelx/cell/base'
-require 'roo/excelx/cell/datetime'
-require 'roo/excelx/cell/time'
-require 'roo/link'
+require 'test_helper'
 
 class TestRooExcelxCellTime < Minitest::Test
   def time