Extract method to generate the json result

Author: rafaelfranca

lib/benchmark_runner.rb

@@ -18,6 +18,20 @@ def output_path(out_path_dir, out_override: nil)
       end
     end
 
+    # Write benchmark data to JSON file
+    def write_json(output_path, ruby_descriptions, bench_data)
+      out_json_path = output_path + ".json"
+      File.open(out_json_path, "w") do |file|
+        out_data = {
+          metadata: ruby_descriptions,
+          raw_data: bench_data,
+        }
+        json_str = JSON.generate(out_data)
+        file.write json_str
+      end
+      out_json_path
+    end
+
     # Render a graph from JSON benchmark data
     def render_graph(json_path)
       png_path = json_path.sub(/\.json$/, '.png')

run_benchmarks.rb

@@ -69,15 +69,7 @@
 output_path = BenchmarkRunner.output_path(args.out_path, out_override: args.out_override)
 
 # Save the raw data as JSON
-out_json_path = output_path + ".json"
-File.open(out_json_path, "w") do |file|
-  out_data = {
-    metadata: ruby_descriptions,
-    raw_data: bench_data,
-  }
-  json_str = JSON.generate(out_data)
-  file.write json_str
-end
+out_json_path = BenchmarkRunner.write_json(output_path, ruby_descriptions, bench_data)
 
 # 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

test/benchmark_runner_test.rb

@@ -180,6 +180,93 @@
     end
   end
 
+  describe '.write_json' do
+    it 'writes JSON file with metadata and raw 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'
+        }
+        bench_data = {
+          'ruby-base' => { 'fib' => { 'time' => 1.5 } },
+          'ruby-yjit' => { 'fib' => { 'time' => 1.0 } }
+        }
+
+        result_path = BenchmarkRunner.write_json(output_path, ruby_descriptions, bench_data)
+
+        expected_path = File.join(dir, 'output_001.json')
+        assert_equal expected_path, result_path
+        assert File.exist?(expected_path)
+
+        json_content = JSON.parse(File.read(expected_path))
+        assert_equal ruby_descriptions, json_content['metadata']
+        assert_equal bench_data, json_content['raw_data']
+      end
+    end
+
+    it 'returns the JSON file path' do
+      Dir.mktmpdir do |dir|
+        output_path = File.join(dir, 'output_test')
+        result_path = BenchmarkRunner.write_json(output_path, {}, {})
+
+        assert_equal File.join(dir, 'output_test.json'), result_path
+      end
+    end
+
+    it 'handles empty metadata and bench data' do
+      Dir.mktmpdir do |dir|
+        output_path = File.join(dir, 'output_empty')
+
+        result_path = BenchmarkRunner.write_json(output_path, {}, {})
+
+        assert File.exist?(result_path)
+        json_content = JSON.parse(File.read(result_path))
+        assert_equal({}, json_content['metadata'])
+        assert_equal({}, json_content['raw_data'])
+      end
+    end
+
+    it 'handles nested benchmark data structures' do
+      Dir.mktmpdir do |dir|
+        output_path = File.join(dir, 'output_nested')
+        ruby_descriptions = { 'ruby' => 'ruby 3.3.0' }
+        bench_data = {
+          'ruby' => {
+            'benchmark1' => {
+              'time' => 1.5,
+              'rss' => 12345,
+              'iterations' => [1.4, 1.5, 1.6]
+            }
+          }
+        }
+
+        result_path = BenchmarkRunner.write_json(output_path, ruby_descriptions, bench_data)
+
+        json_content = JSON.parse(File.read(result_path))
+        assert_equal bench_data, json_content['raw_data']
+      end
+    end
+
+    it 'overwrites existing JSON file' do
+      Dir.mktmpdir do |dir|
+        output_path = File.join(dir, 'output_overwrite')
+
+        # Write first version
+        BenchmarkRunner.write_json(output_path, { 'v' => '1' }, { 'd' => '1' })
+
+        # Write second version
+        new_metadata = { 'v' => '2' }
+        new_data = { 'd' => '2' }
+        result_path = BenchmarkRunner.write_json(output_path, new_metadata, new_data)
+
+        json_content = JSON.parse(File.read(result_path))
+        assert_equal new_metadata, json_content['metadata']
+        assert_equal new_data, json_content['raw_data']
+      end
+    end
+  end
+
   describe '.render_graph' do
     it 'delegates to GraphRenderer and returns calculated png_path' do
       Dir.mktmpdir do |dir|