Allow optional deletion of the raw json results.

This allows downstream users of ruby-bench to configure where the
results.json files are to be stored, so they can use them directly,
rather than having them deleted by ruby-bench after processing

Author: eightbitraptor

lib/benchmark_suite.rb

@@ -43,15 +43,16 @@ def run(ruby:, ruby_description:)
     benchmark_entries = discover_benchmarks
     cmd_prefix = base_cmd(ruby_description)
     env = benchmark_env(ruby)
+    caller_json_path = ENV["RESULT_JSON_PATH"]
 
     benchmark_entries.each_with_index do |entry, idx|
       puts("Running benchmark \"#{entry.name}\" (#{idx+1}/#{benchmark_entries.length})")
 
-      result_json_path = File.join(out_path, "temp#{Process.pid}.json")
+      result_json_path = caller_json_path || File.join(out_path, "temp#{Process.pid}.json")
       result = run_single_benchmark(entry.script_path, result_json_path, ruby, cmd_prefix, env)
 
       if result[:success]
-        bench_data[entry.name] = process_benchmark_result(result_json_path, result[:command])
+        bench_data[entry.name] = process_benchmark_result(result_json_path, result[:command], delete_file: !caller_json_path)
       else
         bench_failures[entry.name] = result[:status].exitstatus
       end
@@ -74,10 +75,10 @@ def setup_benchmark_directories
     end
   end
 
-  def process_benchmark_result(result_json_path, command)
+  def process_benchmark_result(result_json_path, command, delete_file: true)
     JSON.parse(File.read(result_json_path)).tap do |json|
       json["command_line"] = command
-      File.unlink(result_json_path)
+      File.unlink(result_json_path) if delete_file
     end
   end
 

test/benchmark_suite_test.rb

@@ -40,6 +40,7 @@
   end
 
   after do
+    ENV.delete('RESULT_JSON_PATH')
     Dir.chdir(@original_dir)
     FileUtils.rm_rf(@temp_dir)
   end
@@ -424,6 +425,30 @@
       assert_empty temp_files
     end
 
+    it 'uses RESULT_JSON_PATH env var when set and preserves the file' do
+      custom_json_path = File.join(@out_path, 'custom_result.json')
+      ENV['RESULT_JSON_PATH'] = custom_json_path
+
+      suite = BenchmarkSuite.new(
+        categories: [],
+        name_filters: ['simple'],
+        out_path: @out_path,
+        harness: 'harness',
+        no_pinning: true
+      )
+
+      capture_io do
+        suite.run(ruby: [RbConfig.ruby], ruby_description: 'ruby 3.2.0')
+      end
+
+      assert File.exist?(custom_json_path), "Expected #{custom_json_path} to exist but it was deleted"
+      result = JSON.parse(File.read(custom_json_path))
+      assert_includes result, 'bench'
+    ensure
+      ENV.delete('RESULT_JSON_PATH')
+      FileUtils.rm_f(custom_json_path)
+    end
+
     it 'filters benchmarks by name_filters' do
       # Create multiple benchmarks
       File.write('benchmarks/bench_a.rb', <<~RUBY)