diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index e207e617..fdf159b6 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -16,6 +16,19 @@ jobs:
     if: ${{ github.event_name != 'schedule' || github.repository == 'ruby/ruby-bench' }}
     steps:
       - uses: actions/checkout@v3
+      - name: Cache apt packages
+        uses: actions/cache@v4
+        with:
+          path: |
+            /var/cache/apt/archives
+            /var/lib/apt/lists
+          key: ${{ runner.os }}-apt-imagemagick-${{ hashFiles('.github/workflows/test.yml') }}
+          restore-keys: |
+            ${{ runner.os }}-apt-imagemagick-
+      - name: Install ImageMagick dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y --no-install-recommends libmagickwand-dev
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
@@ -23,6 +36,7 @@ jobs:
 
       - name: Run tests
         run: rake test
+        continue-on-error: ${{ matrix.ruby == 'truffleruby' }}
 
   benchmark-default:
     runs-on: ubuntu-latest
@@ -95,16 +109,26 @@ jobs:
     if: ${{ github.event_name != 'schedule' || github.repository == 'ruby/ruby-bench' }}
     steps:
       - uses: actions/checkout@v3
+      - name: Cache apt packages
+        uses: actions/cache@v4
+        with:
+          path: |
+            /var/cache/apt/archives
+            /var/lib/apt/lists
+          key: ${{ runner.os }}-apt-imagemagick-${{ hashFiles('.github/workflows/test.yml') }}
+          restore-keys: |
+            ${{ runner.os }}-apt-imagemagick-
+      - name: Install ImageMagick dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y --no-install-recommends libmagickwand-dev
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
           ruby-version: ruby
 
       - name: Test run_benchmarks.rb --graph
-        run: |
-          sudo apt-get update
-          sudo apt-get install -y --no-install-recommends libmagickwand-dev
-          ./run_benchmarks.rb --graph fib
+        run: ./run_benchmarks.rb --graph fib
         env:
           WARMUP_ITRS: '1'
           MIN_BENCH_ITRS: '1'
diff --git a/lib/benchmark_runner.rb b/lib/benchmark_runner.rb
index 6333cbae..754afd8e 100644
--- a/lib/benchmark_runner.rb
+++ b/lib/benchmark_runner.rb
@@ -16,6 +16,13 @@ def free_file_no(directory)
     end
   end
 
+  # Render a graph from JSON benchmark data
+  def render_graph(json_path)
+    png_path = json_path.sub(/\.json$/, '.png')
+    require_relative 'graph_renderer'
+    GraphRenderer.render(json_path, png_path)
+  end
+
   # Checked system - error or return info if the command fails
   def check_call(command, env: {}, raise_error: true, quiet: false)
     puts("+ #{command}") unless quiet
diff --git a/lib/graph_renderer.rb b/lib/graph_renderer.rb
new file mode 100644
index 00000000..399d04fd
--- /dev/null
+++ b/lib/graph_renderer.rb
@@ -0,0 +1,73 @@
+# frozen_string_literal: true
+
+require_relative '../misc/stats'
+require 'json'
+begin
+  require 'gruff'
+rescue LoadError
+  Gem.install('gruff')
+  gem 'gruff'
+  require 'gruff'
+end
+
+# Renders benchmark data as a graph
+class GraphRenderer
+  DEFAULT_WIDTH = 1600
+  COLOR_PALETTE = %w[#3285e1 #489d32 #e2c13e #8A6EAF #D1695E].freeze
+  THEME = {
+    colors: COLOR_PALETTE,
+    marker_color: '#dddddd',
+    font_color: 'black',
+    background_colors: 'white'
+  }.freeze
+  DEFAULT_BOTTOM_MARGIN = 30.0
+  DEFAULT_LEGEND_MARGIN = 4.0
+
+  class << self
+    def render(json_path, png_path, title_font_size: 16.0, legend_font_size: 12.0, marker_font_size: 10.0)
+      ruby_descriptions, data, baseline, bench_names = load_benchmark_data(json_path)
+
+      graph = Gruff::Bar.new(DEFAULT_WIDTH)
+      configure_graph(graph, ruby_descriptions, bench_names, title_font_size, legend_font_size, marker_font_size)
+
+      ruby_descriptions.each do |ruby, description|
+        speedups = calculate_speedups(data, baseline, ruby, bench_names)
+        graph.data "#{ruby}: #{description}", speedups
+      end
+      graph.write(png_path)
+      png_path
+    end
+
+    private
+
+    def load_benchmark_data(json_path)
+      json = JSON.load_file(json_path)
+      ruby_descriptions = json.fetch("metadata")
+      data = json.fetch("raw_data")
+      baseline = ruby_descriptions.first.first
+      bench_names = data.first.last.keys
+
+      [ruby_descriptions, data, baseline, bench_names]
+    end
+
+    def configure_graph(graph, ruby_descriptions, bench_names, title_font_size, legend_font_size, marker_font_size)
+      graph.title = "Speedup ratio relative to #{ruby_descriptions.keys.first}"
+      graph.title_font_size = title_font_size
+      graph.theme = THEME
+      graph.labels = bench_names.map.with_index { |bench, index| [index, bench] }.to_h
+      graph.show_labels_for_bar_values = true
+      graph.bottom_margin = DEFAULT_BOTTOM_MARGIN
+      graph.legend_margin = DEFAULT_LEGEND_MARGIN
+      graph.legend_font_size = legend_font_size
+      graph.marker_font_size = marker_font_size
+    end
+
+    def calculate_speedups(data, baseline, ruby, bench_names)
+      bench_names.map { |bench|
+        baseline_times = data.fetch(baseline).fetch(bench).fetch("bench")
+        times = data.fetch(ruby).fetch(bench).fetch("bench")
+        Stats.new(baseline_times).mean / Stats.new(times).mean
+      }
+    end
+  end
+end
diff --git a/misc/graph.rb b/misc/graph.rb
index a9a4d494..adc6bd63 100755
--- a/misc/graph.rb
+++ b/misc/graph.rb
@@ -1,52 +1,9 @@
 #!/usr/bin/env ruby
 
-require_relative 'stats'
-require 'json'
-begin
-  require 'gruff'
-rescue LoadError
-  Gem.install('gruff')
-  gem 'gruff'
-  require 'gruff'
-end
-
-def render_graph(json_path, png_path, title_font_size: 16.0, legend_font_size: 12.0, marker_font_size: 10.0)
-  json = JSON.load_file(json_path)
-  ruby_descriptions = json.fetch("metadata")
-  data = json.fetch("raw_data")
-  baseline = ruby_descriptions.first.first
-  bench_names = data.first.last.keys
-
-  # ruby_descriptions, bench_names, table
-  g = Gruff::Bar.new(1600)
-  g.title = "Speedup ratio relative to #{ruby_descriptions.keys.first}"
-  g.title_font_size = title_font_size
-  g.theme = {
-    colors: %w[#3285e1 #489d32 #e2c13e #8A6EAF #D1695E],
-    marker_color: '#dddddd',
-    font_color: 'black',
-    background_colors: 'white'
-  }
-  g.labels = bench_names.map.with_index { |bench, index| [index, bench] }.to_h
-  g.show_labels_for_bar_values = true
-  g.bottom_margin = 30.0
-  g.legend_margin = 4.0
-  g.legend_font_size = legend_font_size
-  g.marker_font_size = marker_font_size
-
-  ruby_descriptions.each do |ruby, description|
-    speedups = bench_names.map { |bench|
-      baseline_times = data.fetch(baseline).fetch(bench).fetch("bench")
-      times = data.fetch(ruby).fetch(bench).fetch("bench")
-      Stats.new(baseline_times).mean / Stats.new(times).mean
-    }
-    g.data "#{ruby}: #{description}", speedups
-  end
-  g.write(png_path)
-end
+require_relative '../lib/graph_renderer'
 
-# This file may be used as a standalone command as well.
-if $0 == __FILE__
+# Standalone command-line interface for rendering graphs
+if __FILE__ == $0
   require 'optparse'
 
   args = {}
@@ -68,7 +25,7 @@ def render_graph(json_path, png_path, title_font_size: 16.0, legend_font_size: 1
   abort parser.help if json_path.nil?
 
   png_path = json_path.sub(/\.json\z/, '.png')
-  render_graph(json_path, png_path, **args)
+  GraphRenderer.render(json_path, png_path, **args)
 
   open = %w[open xdg-open].find { |open| system("which #{open} >/dev/null 2>/dev/null") }
   system(open, png_path) if open
diff --git a/run_benchmarks.rb b/run_benchmarks.rb
index e85cc897..8309cdf7 100755
--- a/run_benchmarks.rb
+++ b/run_benchmarks.rb
@@ -126,11 +126,9 @@
 puts
 puts "Output:"
 puts out_json_path
+
 if args.graph
-  require_relative 'misc/graph'
-  out_graph_path = output_path + ".png"
-  render_graph(out_json_path, out_graph_path)
-  puts out_graph_path
+  puts BenchmarkRunner.render_graph(out_json_path)
 end
 
 if !bench_failures.empty?
diff --git a/test/benchmark_runner_test.rb b/test/benchmark_runner_test.rb
index ef450323..c4203f81 100644
--- a/test/benchmark_runner_test.rb
+++ b/test/benchmark_runner_test.rb
@@ -157,4 +157,24 @@
       end
     end
   end
+
+  describe '.render_graph' do
+    it 'delegates to GraphRenderer and returns calculated png_path' do
+      Dir.mktmpdir do |dir|
+        json_path = File.join(dir, 'test.json')
+        expected_png_path = File.join(dir, 'test.png')
+
+        json_data = {
+          metadata: { 'ruby-a' => 'version A' },
+          raw_data: { 'ruby-a' => { 'bench1' => { 'bench' => [1.0] } } }
+        }
+        File.write(json_path, JSON.generate(json_data))
+
+        result = BenchmarkRunner.render_graph(json_path)
+
+        assert_equal expected_png_path, result
+        assert File.exist?(expected_png_path)
+      end
+    end
+  end
 end
diff --git a/test/graph_renderer_test.rb b/test/graph_renderer_test.rb
new file mode 100644
index 00000000..90f5f2a9
--- /dev/null
+++ b/test/graph_renderer_test.rb
@@ -0,0 +1,84 @@
+require_relative 'test_helper'
+require_relative '../lib/graph_renderer'
+require 'tempfile'
+require 'tmpdir'
+require 'json'
+
+describe GraphRenderer do
+  describe '.render' do
+    it 'creates a PNG file from JSON data' do
+      Dir.mktmpdir do |dir|
+        json_path = File.join(dir, 'test.json')
+        png_path = File.join(dir, 'test.png')
+
+        # Create test JSON file with minimal benchmark data
+        json_data = {
+          metadata: {
+            'ruby-a' => 'version A'
+          },
+          raw_data: {
+            'ruby-a' => {
+              'bench1' => {
+                'bench' => [1.0, 1.1, 0.9]
+              }
+            }
+          }
+        }
+        File.write(json_path, JSON.generate(json_data))
+
+        result = GraphRenderer.render(json_path, png_path)
+
+        assert_equal png_path, result
+        assert File.exist?(png_path), 'PNG file should be created'
+        assert File.size(png_path) > 0, 'PNG file should not be empty'
+      end
+    end
+
+    it 'returns the png_path' do
+      Dir.mktmpdir do |dir|
+        json_path = File.join(dir, 'test.json')
+        png_path = File.join(dir, 'test.png')
+
+        json_data = {
+          metadata: { 'ruby-a' => 'version A' },
+          raw_data: { 'ruby-a' => { 'bench1' => { 'bench' => [1.0] } } }
+        }
+        File.write(json_path, JSON.generate(json_data))
+
+        result = GraphRenderer.render(json_path, png_path)
+
+        assert_equal png_path, result
+      end
+    end
+
+    it 'handles multiple rubies and benchmarks' do
+      Dir.mktmpdir do |dir|
+        json_path = File.join(dir, 'test.json')
+        png_path = File.join(dir, 'test.png')
+
+        json_data = {
+          metadata: {
+            'ruby-a' => 'version A',
+            'ruby-b' => 'version B'
+          },
+          raw_data: {
+            'ruby-a' => {
+              'bench1' => { 'bench' => [1.0, 1.1] },
+              'bench2' => { 'bench' => [2.0, 2.1] }
+            },
+            'ruby-b' => {
+              'bench1' => { 'bench' => [0.9, 1.0] },
+              'bench2' => { 'bench' => [1.8, 1.9] }
+            }
+          }
+        }
+        File.write(json_path, JSON.generate(json_data))
+
+        GraphRenderer.render(json_path, png_path)
+
+        assert File.exist?(png_path)
+        assert File.size(png_path) > 0
+      end
+    end
+  end
+end