Make sure golden file matches output of regression test, during warmup (#544)

This is more of a sanity check

Author: stephenamar-db

bench/src/sjsonnet/bench/RegressionBenchmark.scala

@@ -4,7 +4,7 @@ import org.openjdk.jmh.annotations.*
 import org.openjdk.jmh.infra.*
 import sjsonnet.*
 
-import java.io.{OutputStream, PrintStream, StringWriter}
+import java.io.{OutputStream, PrintStream, ByteArrayOutputStream}
 import java.util.concurrent.TimeUnit
 
 object RegressionBenchmark {
@@ -31,6 +31,32 @@ class RegressionBenchmark {
 
   private val dummyOut = RegressionBenchmark.createDummyOut
 
+  @Setup(Level.Trial)
+  def setup(): Unit = {
+    val baos = new ByteArrayOutputStream()
+    val ps = new PrintStream(baos)
+    SjsonnetMainBase.main0(
+      Array(path),
+      new DefaultParseCache,
+      System.in,
+      ps,
+      System.err,
+      RegressionBenchmark.testSuiteRoot,
+      None
+    )
+    ps.close()
+    baos.close()
+    val golden = os.read(os.Path(path + ".golden", RegressionBenchmark.testSuiteRoot)).stripLineEnd
+    if (baos.toString("UTF-8").stripLineEnd != golden) {
+      System.err.println(
+        "Golden output mismatch:\n%s != %s".format(
+          baos.toString("UTF-8").stripLineEnd,
+          golden
+        )
+      )
+    }
+  }
+
   @Benchmark
   def main(bh: Blackhole): Unit = {
     bh.consume(