adding more tests to Writer class

CHANGELOG.md

@@ -2,7 +2,8 @@
 # SmarterCSV 1.x Change Log
 
 ## 1.11.0
-  * added feature to output CSV files ([issue #44](https://github.com/tilo/smarter_csv/issues/44))
+  * added SmarterCSV::Writer to output CSV files ([issue #44](https://github.com/tilo/smarter_csv/issues/44))
+  * added SmarterCSV::Reader to isolate parsing of CSV files
 
 ## 1.10.3 (2024-03-10)
   * fixed issue when frozen options are handed in (thanks to Daniel Pepper)

lib/smarter_csv.rb

@@ -10,7 +10,7 @@
 require "smarter_csv/headers"
 require "smarter_csv/hash_transformations"
 require "smarter_csv/parse"
-require "smarter_csv/generator"
+require "smarter_csv/writer"
 
 # load the C-extension:
 case RUBY_ENGINE

lib/smarter_csv/generator.rb → lib/smarter_csv/writer.rb

@@ -9,15 +9,16 @@ module SmarterCSV
   # Optionally headers can be passed-in via the options,
   # If any new headers are fund in the data, they will be appended to the headers.
   #
-  class Generator
+  class Writer
     def initialize(file_path, options = {})
       @options = options
       @discover_headers = options.has_key?(:discover_headers) ? (options[:discover_headers] == true) : true
       @headers = options[:headers] || []
       @col_sep = options[:col_sep] || ','
       @force_quotes = options[:force_quotes]
       @map_headers = options[:map_headers] || {}
-      @file = File.open(file_path, 'w+')
+      @temp_file = Tempfile.new('tempfile', '/tmp')
+      @output_file = File.open(file_path, 'w+')
     end
 
     def append(array_of_hashes)
@@ -29,25 +30,26 @@ def append(array_of_hashes)
         # Reorder the hash to match the current headers order and fill missing fields
         ordered_row = @headers.map { |header| hash[header] || '' }
 
-        @file.puts ordered_row.map { |value| escape_csv_field(value) }.join(@col_sep)
+        @temp_file.puts ordered_row.map { |value| escape_csv_field(value) }.join(@col_sep)
       end
     end
 
     def finalize
       # Map headers if :map_headers option is provided
       mapped_headers = @headers.map { |header| @map_headers[header] || header }
 
-      # Rewind to the beginning of the file to write the headers
-      @file.rewind
-      @file.write(mapped_headers.join(@col_sep) + "\n")
-      @file.flush # Ensure all data is written to the file
-      @file.close
+      @temp_file.rewind
+      @output_file.write(mapped_headers.join(@col_sep) + "\n")
+      @output_file.write(@temp_file.read)
+      @output_file.flush
+      @output_file.close
     end
 
     private
 
+    SPECIAL_CHARS = /[,\"\n]/
     def escape_csv_field(field)
-      if @force_quotes || field.to_s.include?(@col_sep)
+      if @force_quotes || field.to_s.match(SPECIAL_CHARS)
         "\"#{field}\""
       else
         field.to_s

spec/smarter_csv/writer_spec.rb

@@ -0,0 +1,229 @@
+# frozen_string_literal: true
+
+RSpec.describe SmarterCSV::Writer do
+  subject(:create_csv_file) do
+    writer = SmarterCSV::Writer.new(file_path, options)
+    data_batches.each { |batch| writer.append(batch) }
+    writer.finalize
+  end
+  let(:file_path) { '/tmp/test_output.csv' }
+
+  after(:each) do
+    File.delete(file_path) if File.exist?(file_path)
+  end
+
+  let(:data_batches) do
+    [
+      [
+        { name: 'John', age: 30, city: 'New York' },
+        { name: 'Jane', age: 25, country: 'USA' }
+      ],
+      [
+        { name: 'Mike', age: 35, city: 'Chicago', state: 'IL' }
+      ]
+    ]
+  end
+
+  context 'when headers are given in advance' do
+    let(:options) { { headers: %i[name age city] } }
+
+    it 'writes the given headers and data correctly' do
+      create_csv_file
+      output = File.read(file_path)
+
+      expect(output).to include("name,age,city,country,state\n")
+      expect(output).to include("John,30,New York\n")
+      expect(output).to include("Jane,25,,USA\n")
+      expect(output).to include("Mike,35,Chicago,,IL\n")
+    end
+  end
+
+  context 'when headers are automatically discovered' do
+    let(:options) { {} }
+
+    it 'writes the discovered headers and data correctly' do
+      create_csv_file
+      output = File.read(file_path)
+
+      expect(output).to include("name,age,city,country,state\n")
+      expect(output).to include("John,30,New York\n")
+      expect(output).to include("Jane,25,,USA\n")
+      expect(output).to include("Mike,35,Chicago,,IL\n")
+    end
+  end
+
+  context 'when headers are mapped' do
+    let(:options) do
+      {
+        map_headers: {
+          name: 'Full Name',
+          age: 'Age',
+          city: 'City',
+          country: 'Country',
+          state: 'State',
+        }
+      }
+    end
+
+    it 'writes the mapped headers and data correctly' do
+      create_csv_file
+      output = File.read(file_path)
+
+      expect(output).to include("Full Name,Age,City,Country,State\n")
+      expect(output).to include("John,30,New York\n")
+      expect(output).to include("Jane,25,,USA\n")
+      expect(output).to include("Mike,35,Chicago,,IL\n")
+    end
+  end
+
+  context 'Initialization with Default Options' do
+    it 'initializes with default options' do
+      writer = SmarterCSV::Writer.new(file_path)
+      expect(writer.instance_variable_get(:@discover_headers)).to be true
+      expect(writer.instance_variable_get(:@headers)).to eq([])
+      expect(writer.instance_variable_get(:@col_sep)).to eq(',')
+    end
+  end
+
+  context 'Initialization with Custom Options' do
+    it 'initializes with custom options' do
+      options = { discover_headers: false, headers: ['a', 'b'], col_sep: ';', force_quotes: true, map_headers: { 'a' => 'A' } }
+      writer = SmarterCSV::Writer.new(file_path, options)
+      expect(writer.instance_variable_get(:@discover_headers)).to be false
+      expect(writer.instance_variable_get(:@headers)).to eq(['a', 'b'])
+      expect(writer.instance_variable_get(:@col_sep)).to eq(';')
+      expect(writer.instance_variable_get(:@force_quotes)).to be true
+      expect(writer.instance_variable_get(:@map_headers)).to eq({ 'a' => 'A' })
+    end
+  end
+
+  context 'Appending Data' do
+    it 'appends multiple hashes over multiple calls' do
+      writer = SmarterCSV::Writer.new(file_path)
+      writer.append([{ a: 1, b: 2 }, {c: 3}])
+      writer.append([{ d: 4, a: 5 }])
+      writer.finalize
+      output = File.read(file_path)
+
+      expect(output).to include("a,b,c,d\n")
+      expect(output).to include("1,2\n")
+      expect(output).to include(",,3\n")
+      expect(output).to include("5,,,4\n")
+    end
+
+    it 'appends with existing headers' do
+      options = { headers: [:a] }
+      writer = SmarterCSV::Writer.new(file_path, options)
+      writer.append([{ a: 1, b: 2 }])
+      writer.finalize
+
+      expect(File.read(file_path)).to eq("a,b\n1,2\n")
+    end
+
+    it 'appends with missing fields' do
+      writer = SmarterCSV::Writer.new(file_path)
+      writer.append([{ a: 1, b: 2 }, { a: 3 }])
+      writer.finalize
+
+      expect(File.read(file_path)).to eq("a,b\n1,2\n3,\n")
+    end
+  end
+
+  context 'Finalizing the Output File' do
+    it 'maps headers' do
+      options = { map_headers: { a: 'A', b: 'B' } }
+      writer = SmarterCSV::Writer.new(file_path, options)
+      writer.append([{ a: 1, b: 2 }])
+      writer.finalize
+
+      expect(File.read(file_path)).to eq("A,B\n1,2\n")
+    end
+
+    it 'writes header and appends content to output file' do
+      writer = SmarterCSV::Writer.new(file_path)
+      writer.append([{ a: 1, b: 2 }])
+      writer.finalize
+
+      expect(File.read(file_path)).to eq("a,b\n1,2\n")
+    end
+
+    it 'properly closes the output file' do
+      writer = SmarterCSV::Writer.new(file_path)
+      writer.append([{ a: 1, b: 2 }])
+      writer.finalize
+
+      expect(File).to be_exist(file_path)
+    end
+  end
+
+  context 'CSV Field Escaping' do
+    it 'does not quote fields without commas unless force_quotes is enabled' do
+      writer = SmarterCSV::Writer.new(file_path)
+      writer.append([{ a: 'hello', b: 'world' }])
+      writer.finalize
+
+      expect(File.read(file_path)).to eq("a,b\nhello,world\n")
+    end
+
+    it 'quotes fields with column separator' do
+      writer = SmarterCSV::Writer.new(file_path)
+      writer.append([{ a: 'hello, world', b: 'test' }])
+      writer.finalize
+
+      expect(File.read(file_path)).to eq("a,b\n\"hello, world\",test\n")
+    end
+
+    it 'quotes all fields when force_quotes is enabled' do
+      options = { force_quotes: true }
+      writer = SmarterCSV::Writer.new(file_path, options)
+      writer.append([{ a: 'hello', b: 'world' }])
+      writer.finalize
+
+      expect(File.read(file_path)).to eq("a,b\n\"hello\",\"world\"\n")
+    end
+  end
+
+  context 'Edge Cases' do
+    it 'handles empty hash' do
+      writer = SmarterCSV::Writer.new(file_path)
+      writer.append([{}])
+      writer.finalize
+
+      expect(File.read(file_path)).to eq("\n\n")
+    end
+
+    it 'handles empty array' do
+      writer = SmarterCSV::Writer.new(file_path)
+      writer.append([])
+      writer.finalize
+
+      expect(File.read(file_path)).to eq("\n")
+    end
+
+    it 'handles special characters in data' do
+      writer = SmarterCSV::Writer.new(file_path)
+      writer.append([{ a: "hello\nworld", b: 'quote"test' }])
+      writer.finalize
+
+      expect(File.read(file_path)).to eq("a,b\n\"hello\nworld\",\"quote\"test\"\n")
+    end
+  end
+
+  context 'Error Handling' do
+    it 'handles file access issues' do
+      allow(File).to receive(:open).and_raise(Errno::EACCES)
+
+      expect {
+        SmarterCSV::Writer.new(file_path)
+      }.to raise_error(Errno::EACCES)
+    end
+
+    it 'handles tempfile issues' do
+      allow(Tempfile).to receive(:new).and_raise(Errno::ENOENT)
+
+      expect {
+        SmarterCSV::Writer.new(file_path)
+      }.to raise_error(Errno::ENOENT)
+    end
+  end
+end