Merge pull request #12 from szkiba/feature/benchmarking

feat: measuring the time required for transformation

README.md

@@ -126,4 +126,8 @@ Before the test run, transpilation and bundling are done on the fly.
 
 ## Compatibility warning
 
-xk6-ts is currently integrated into k6 by modifying the execution of the `k6 run` command. This is a temporary solution, the final integration will be done in a different way. This temporary integration assumes that the last argument of the `k6 run` command line is the name of the script file. That is, contrary to the way the original `k6 run` command line works, xk6-ts does not accept flags after the script file name. By the way, this assumption is not uncommon, many other commands only accept flags before positional arguments. (the original `k6 run` command also accepts flags after the positional argument).
+xk6-ts is currently integrated into k6 by modifying the execution of the `k6 run` command. This is a temporary solution, the final integration will be done in a different way. This temporary integration assumes that the last argument of the `k6 run` command line is the name of the script file. That is, contrary to the way the original `k6 run` command line works, xk6-ts does not accept flags after the script file name. By the way, this assumption is not uncommon, many other commands only accept flags before positional arguments. (the original `k6 run` command also accepts flags after the positional argument).
+
+## Benchmarking
+
+Setting the `XK6_TS_BENCHMARK` environment variable to `true` will log the time spent on TypeScript/JavaScript bundling. This time also includes downloading any remote modules.

loader.go

@@ -4,6 +4,7 @@ package ts
 import (
 	"os"
 	"path/filepath"
+	"time"
 
 	"github.com/sirupsen/logrus"
 	"github.com/szkiba/k6pack"
@@ -65,11 +66,18 @@ func redirectStdin() {
 		logrus.WithError(err).Fatal()
 	}
 
+	packStarted := time.Now()
+
 	jsScript, err := k6pack.Pack(string(source), opts)
 	if err != nil {
 		logrus.WithError(err).Fatal()
 	}
 
+	if os.Getenv("XK6_TS_BENCHMARK") == "true" {
+		duration := time.Since(packStarted)
+		logrus.WithField("extension", "xk6-ts").WithField("duration", duration).Info("Bundling completed in ", duration)
+	}
+
 	os.Args[scriptIndex] = "-"
 
 	reader, writer, err := os.Pipe()