Extract method to generate the csv fike

Author: rafaelfranca

lib/benchmark_runner.rb

@@ -29,6 +29,24 @@ def write_json(output_path, ruby_descriptions, bench_data)
       out_json_path
     end
 
+    # Write benchmark results to CSV file
+    def write_csv(output_path, ruby_descriptions, table)
+      out_csv_path = "#{output_path}.csv"
+      output_rows = []
+      ruby_descriptions.each do |key, value|
+        output_rows.append([key, value])
+      end
+      output_rows.append([])
+      output_rows.concat(table)
+
+      CSV.open(out_csv_path, "wb") do |csv|
+        output_rows.each do |row|
+          csv << row
+        end
+      end
+      out_csv_path
+    end
+
     # Render a graph from JSON benchmark data
     def render_graph(json_path)
       png_path = json_path.sub(/\.json$/, '.png')

run_benchmarks.rb

@@ -74,18 +74,7 @@
 # Save data as CSV so we can produce tables/graphs in a spreasheet program
 # NOTE: we don't do any number formatting for the output file because
 #       we don't want to lose any precision
-output_rows = []
-ruby_descriptions.each do |key, value|
-  output_rows.append([key, value])
-end
-output_rows.append([])
-output_rows.concat(table)
-out_tbl_path = output_path + ".csv"
-CSV.open(out_tbl_path, "wb") do |csv|
-  output_rows.each do |row|
-    csv << row
-  end
-end
+BenchmarkRunner.write_csv(output_path, ruby_descriptions, table)
 
 # Save the output in a text file that we can easily refer to
 output_str = ""

test/benchmark_runner_test.rb

@@ -180,6 +180,104 @@
     end
   end
 
+  describe '.write_csv' do
+    it 'writes CSV file with metadata and table data' do
+      Dir.mktmpdir do |dir|
+        output_path = File.join(dir, 'output_001')
+        ruby_descriptions = {
+          'ruby-base' => 'ruby 3.3.0',
+          'ruby-yjit' => 'ruby 3.3.0 +YJIT'
+        }
+        table = [
+          ['Benchmark', 'ruby-base', 'ruby-yjit'],
+          ['fib', '1.5', '1.0'],
+          ['matmul', '2.0', '1.8']
+        ]
+
+        result_path = BenchmarkRunner.write_csv(output_path, ruby_descriptions, table)
+
+        expected_path = File.join(dir, 'output_001.csv')
+        assert_equal expected_path, result_path
+        assert File.exist?(expected_path)
+
+        csv_rows = CSV.read(expected_path)
+        assert_equal 'ruby-base', csv_rows[0][0]
+        assert_equal 'ruby 3.3.0', csv_rows[0][1]
+        assert_equal 'ruby-yjit', csv_rows[1][0]
+        assert_equal 'ruby 3.3.0 +YJIT', csv_rows[1][1]
+        assert_equal [], csv_rows[2]
+        assert_equal table, csv_rows[3..5]
+      end
+    end
+
+    it 'returns the CSV file path' do
+      Dir.mktmpdir do |dir|
+        output_path = File.join(dir, 'output_test')
+        result_path = BenchmarkRunner.write_csv(output_path, {}, [])
+
+        assert_equal File.join(dir, 'output_test.csv'), result_path
+      end
+    end
+
+    it 'handles empty metadata and table' do
+      Dir.mktmpdir do |dir|
+        output_path = File.join(dir, 'output_empty')
+
+        result_path = BenchmarkRunner.write_csv(output_path, {}, [])
+
+        assert File.exist?(result_path)
+        csv_rows = CSV.read(result_path)
+        assert_equal [[]], csv_rows
+      end
+    end
+
+    it 'handles single metadata entry' do
+      Dir.mktmpdir do |dir|
+        output_path = File.join(dir, 'output_single')
+        ruby_descriptions = { 'ruby' => 'ruby 3.3.0' }
+        table = [['Benchmark', 'Time'], ['test', '1.0']]
+
+        result_path = BenchmarkRunner.write_csv(output_path, ruby_descriptions, table)
+
+        csv_rows = CSV.read(result_path)
+        assert_equal 'ruby', csv_rows[0][0]
+        assert_equal 'ruby 3.3.0', csv_rows[0][1]
+        assert_equal [], csv_rows[1]
+        assert_equal table, csv_rows[2..3]
+      end
+    end
+
+    it 'preserves precision in numeric strings' do
+      Dir.mktmpdir do |dir|
+        output_path = File.join(dir, 'output_precision')
+        table = [['Benchmark', 'Time'], ['test', '1.234567890123']]
+
+        result_path = BenchmarkRunner.write_csv(output_path, {}, table)
+
+        csv_rows = CSV.read(result_path)
+        assert_equal '1.234567890123', csv_rows[2][1]
+      end
+    end
+
+    it 'overwrites existing CSV file' do
+      Dir.mktmpdir do |dir|
+        output_path = File.join(dir, 'output_overwrite')
+
+        # Write first version
+        BenchmarkRunner.write_csv(output_path, { 'v1' => 'first' }, [['old']])
+
+        # Write second version
+        new_descriptions = { 'v2' => 'second' }
+        new_table = [['new']]
+        result_path = BenchmarkRunner.write_csv(output_path, new_descriptions, new_table)
+
+        csv_rows = CSV.read(result_path)
+        assert_equal 'v2', csv_rows[0][0]
+        assert_equal 'second', csv_rows[0][1]
+      end
+    end
+  end
+
   describe '.write_json' do
     it 'writes JSON file with metadata and raw data' do
       Dir.mktmpdir do |dir|