fix for issue #299 : empty hash

Author: tilo

.rubocop.yml

@@ -58,6 +58,9 @@ Style/ClassMethods:
 Style/ConditionalAssignment:
   Enabled: false
 
+Style/CommentAnnotation:
+  Enabled: false
+
 Style/CommentedKeyword:
   Enabled: false
 
@@ -76,6 +79,9 @@ Style/Encoding:
 Style/EvalWithLocation:
   Enabled: false
 
+Style/EvenOdd:
+  Enabled: false
+
 Style/FormatString:
   Enabled: false
 
@@ -94,6 +100,9 @@ Style/IfUnlessModifier:
 Style/InverseMethods:
   Enabled: false
 
+Style/Lambda:
+  Enabled: false
+
 Style/NestedTernaryOperator:
   Enabled: false
 
@@ -115,6 +124,9 @@ Style/SafeNavigation:
 Style/SlicingWithRange:
   Enabled: false
 
+Style/SoleNestedConditional:
+  Enabled: false
+
 Style/SpecialGlobalVars: # DANGER: unsafe rule!!
   Enabled: false
 
@@ -135,8 +147,13 @@ Style/SymbolArray:
 Style/SymbolProc: # old Ruby versions can't do this
   Enabled: false
 
+Style/TrailingCommaInArrayLiteral:
+  Enabled: false
+  EnforcedStyleForMultiline: consistent_comma
+
 Style/TrailingCommaInHashLiteral:
   Enabled: false
+  EnforcedStyleForMultiline: consistent_comma
 
 Style/TrailingUnderscoreVariable:
   Enabled: false

lib/smarter_csv/parser.rb

@@ -110,7 +110,7 @@ def cleanup_quotes(field, quote)
       end
 
       # Replace double quotes with a single quote
-      field.gsub!("#{quote * 2}", quote)
+      field.gsub!((quote * 2).to_s, quote)
 
       field
     end

lib/smarter_csv/writer.rb

@@ -90,7 +90,7 @@ def finalize
       mapped_headers = mapped_headers.map { |x| escape_csv_field(x) } if @force_quotes
 
       @temp_file.rewind
-      @output_file.write(mapped_headers.join(@col_sep) + @row_sep)
+      @output_file.write(mapped_headers.join(@col_sep) + @row_sep) unless mapped_headers.empty?
       @output_file.write(@temp_file.read)
       @output_file.flush
       @output_file.close
@@ -120,7 +120,7 @@ def process_hash(hash)
         escape_csv_field(value) # for backwards compatibility
       end
 
-      @temp_file.write ordered_row.join(@col_sep) + @row_sep
+      @temp_file.write(ordered_row.join(@col_sep) + @row_sep) unless ordered_row.empty?
     end
 
     def map_value(key, value)

spec/features/special_cases/malformed_spec.rb

@@ -45,6 +45,5 @@
         end
       end
     end
-
   end
 end

spec/smarter_csv/writer_spec.rb

@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-# rubocop:disable Style/WordArray
 RSpec.describe SmarterCSV::Writer do
   subject(:create_csv_file) do
     writer = SmarterCSV::Writer.new(file_path, options)
@@ -27,6 +26,61 @@
     ]
   end
 
+  context 'when empty data is handed in' do
+    let(:options) { {} }
+
+    subject(:write_csv) do
+      SmarterCSV.generate(file_path, options) do |csv_writer|
+        csv_writer << data
+      end
+    end
+
+    context 'when nil is passed in' do
+      let(:data) { nil }
+      it 'does not generate output' do
+        write_csv
+        output = File.read(file_path)
+        expect(output).to eq ''
+      end
+    end
+
+    context 'when {} is passed in' do
+      let(:data) { {} }
+      it 'does not generate output' do
+        write_csv
+        output = File.read(file_path)
+        expect(output).to eq ''
+      end
+    end
+
+    context 'when [] is passed in' do
+      let(:data) { [] }
+      it 'does not generate output' do
+        write_csv
+        output = File.read(file_path)
+        expect(output).to eq ''
+      end
+    end
+
+    context 'when [{},nil] is passed in' do
+      let(:data) { [{}, nil] }
+      it 'does not generate output' do
+        write_csv
+        output = File.read(file_path)
+        expect(output).to eq ''
+      end
+    end
+
+    context 'when [nil, {}, [], [{},nil]] is passed in' do
+      let(:data) { [nil, {}, [], [{}, nil]] }
+      it 'does not generate output' do
+        write_csv
+        output = File.read(file_path)
+        expect(output).to eq ''
+      end
+    end
+  end
+
   context 'simplest case: one hash given' do
     let(:options) { {} }
     let(:data) do
@@ -236,16 +290,21 @@
       end
     end
 
-    context 'when we explicitly disable header discovery' do
+    # NOTE:
+    #  * setting `discover_headers: false` is implicit when setting :headers or :map_headers
+    #  * that's why it does not make sense to set it manually to `false`.
+    #  * if you want to turn off header discovery, just provide one of those two options
+    #
+    context 'when we explicitly disable header discovery, but do not provide headers' do
       let(:options) do
-        { discover_headers: false } # THIS SHOULD NOT BE USED LIKE THIS!!
+        { discover_headers: false } # THIS DOES NOT MAKE SENSE without providing :headers or :map_headers
       end
 
       it 'limits the CSV file to only the given headers' do
         create_csv_file
 
         output = File.read(file_path)
-        expect(output).to eq "\n\n\n\n\n" # THIS SHOULD NOT BE USED LIKE THIS!!
+        expect(output).to eq '' # because it turns off header discovery and no headers provided
       end
     end
   end
@@ -268,7 +327,6 @@
       end
     end
 
-
     describe 'when special_char row_sep' do
       let(:options) { {} }
       let(:data_batches) do
@@ -339,14 +397,14 @@
                 v.to_s
               end
             end,
-            _all: ->(k, v) { v.is_a?(String) ? "\"#{v}\"" : v } # only double-quote string fields
+            _all: ->(_k, v) { v.is_a?(String) ? "\"#{v}\"" : v } # only double-quote string fields
           }
         }
       end
       it 'applies all mappings in the correct order' do
         writer = SmarterCSV::Writer.new(file_path, options)
         writer << { name: 'Alice', age: 42, active: true, balance: 234.235 }
-        writer << { name: 'Joe', age: 53, active: false, balance: 32100 }
+        writer << { name: 'Joe', age: 53, active: false, balance: 32_100 }
         writer.finalize
 
         output = File.read(file_path)
@@ -389,4 +447,3 @@
     end
   end
 end
-# rubocop:enable Style/WordArray