Check that --graph works in CI

Author: eregon

.github/workflows/test.yml

@@ -40,6 +40,14 @@ jobs:
           MIN_BENCH_TIME: '0'
           SKIP_BENCHMARKS: ${{ matrix.skip }}
 
+      - name: Test run_benchmarks.rb --graph
+        run: ./run_benchmarks.rb --graph fib
+        if: matrix.ruby == 'ruby'
+        env:
+          WARMUP_ITRS: '1'
+          MIN_BENCH_ITRS: '1'
+          MIN_BENCH_TIME: '0'
+
       - name: Test run_once.sh
         run: ./run_once.sh --yjit-stats benchmarks/railsbench/benchmark.rb
         if: matrix.ruby == 'head'