fixes #389 #to_csv: changed predefined arguments and add documentation

README.md

@@ -156,6 +156,18 @@ sheet.to_xml
 sheet.to_yaml
 ```
 
+Specify the file as default argument for `#to_csv`:
+
+```ruby
+sheet.to_csv(File.new("/dev/null"))
+```
+
+specify the custom separator:
+
+```ruby
+sheet.to_csv(separator: ":") # "," using by default
+```
+
 ### Excel (xlsx and xlsm) Support
 
 Stream rows from an Excelx spreadsheet.

lib/roo/formatters/csv.rb

@@ -1,7 +1,15 @@
 module Roo
   module Formatters
     module CSV
-      def to_csv(filename = nil, separator = ",", sheet = default_sheet)
+      def to_csv(filename = nil, old_separator = nil, old_sheet = nil, separator: ",", sheet: default_sheet)
+        if old_separator
+          warn("[DEPRECATION] optional argument for separator is deprecated. Please use keyword argument :separator instead")
+          separator = old_separator
+        end
+        if old_sheet
+          warn("[DEPRECATION] optional argument for sheet is deprecated. Please use keyword argument :sheet instead")
+          sheet = old_sheet
+        end
         if filename
           File.open(filename, "w") do |file|
             write_csv_content(file, sheet, separator)

spec/lib/roo/base_spec.rb

@@ -269,7 +269,21 @@ def sheets
     end
 
     it 'should convert the spreadsheet to csv using the separator when is passed on the parameter' do
-      expect(spreadsheet.to_csv(nil, ';')).to eq(expected_csv_with_semicolons)
+      expect(spreadsheet.to_csv(separator: ';')).to eq(expected_csv_with_semicolons)
+    end
+
+    context 'should contains the deprecation warning message' do
+      it 'convert the spreadsheet to csv using the separator' do
+        converting =-> { spreadsheet.to_csv(nil, ';') }
+        expect(converting.call).to eq(expected_csv_with_semicolons)
+        expect(&converting).to output(/DEPRECATION.*:separator\b/).to_stderr
+      end
+
+      it 'be able to arguments: filename, separator, sheet' do
+        converting =-> { spreadsheet.to_csv(nil, ';', spreadsheet.default_sheet) }
+        expect(converting.call).to eq(expected_csv_with_semicolons)
+        expect(&converting).to output(/DEPRECATION.*:sheet\b/).to_stderr
+      end
     end
   end
 end

spec/spec_helper.rb

@@ -6,4 +6,15 @@
   c.include Helpers
   c.color = true
   c.formatter = :documentation if ENV["USE_REPORTERS"]
+  original_stderr = $stderr
+  original_stdout = $stdout
+  c.before(:all) do
+    # Redirect stderr and stdout
+    $stderr = File.open(File::NULL, "w")
+    $stdout = File.open(File::NULL, "w")
+  end
+  c.after(:all) do
+    $stderr = original_stderr
+    $stdout = original_stdout
+  end
 end