Include all tests in default rake run

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
 

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

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

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

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

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

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

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

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