Adds logging sink that uses the standard logger (#162)

* Renames `newSink` to `newTestSink`

* Adds log sink that uses the standard logger

* Add changelog entry

---------

Co-authored-by: Baraa Basata <bbasata@gmail.com>

Author: gdavison

.changes/unreleased/FEATURES-20251015-121524.yaml

@@ -0,0 +1,5 @@
+kind: FEATURES
+body: Added `tfsdklog.RegisterStdlogSink()` for test sweeper logging
+time: 2025-10-15T12:15:24.302228-04:00
+custom:
+    Issue: "162"

tfsdklog/sink.go

@@ -7,6 +7,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"log"
 	"os"
 	"strings"
 	"sync"
@@ -75,7 +76,7 @@ var invalidLogLevelMessage sync.Once
 // no longer maintained. Use ContextWithTestLogging instead of
 // RegisterTestSink.
 func RegisterTestSink(ctx context.Context, t testing.T) context.Context {
-	logger, loggerOptions := newSink(t.Name())
+	logger, loggerOptions := newTestSink(t.Name())
 
 	ctx = logging.SetSink(ctx, logger)
 	ctx = logging.SetSinkOptions(ctx, loggerOptions)
@@ -93,15 +94,15 @@ func RegisterTestSink(ctx context.Context, t testing.T) context.Context {
 // ContextWithTestLogging must be called prior to any loggers being setup or
 // instantiated.
 func ContextWithTestLogging(ctx context.Context, testName string) context.Context {
-	logger, loggerOptions := newSink(testName)
+	logger, loggerOptions := newTestSink(testName)
 
 	ctx = logging.SetSink(ctx, logger)
 	ctx = logging.SetSinkOptions(ctx, loggerOptions)
 
 	return ctx
 }
 
-func newSink(testName string) (hclog.Logger, *hclog.LoggerOptions) {
+func newTestSink(testName string) (hclog.Logger, *hclog.LoggerOptions) {
 	logOutput := io.Writer(os.Stderr)
 	var json bool
 	var logLevel hclog.Level
@@ -176,3 +177,30 @@ func isValidLogLevel(level string) bool {
 
 	return false
 }
+
+// RegisterStdlogSink sets up a logging sink for use with test sweepers and
+// other cases where plugin logs don't get routed through Terraform and the
+// built-in Go `log` package is also used.
+//
+// RegisterStdlogSink should only ever be called by test sweepers, providers
+// should never call it.
+//
+// RegisterStdlogSink must be called prior to any loggers being setup or
+// instantiated.
+func RegisterStdlogSink(ctx context.Context) context.Context {
+	logger, loggerOptions := newStdlogSink()
+
+	ctx = logging.SetSink(ctx, logger)
+	ctx = logging.SetSinkOptions(ctx, loggerOptions)
+
+	return ctx
+}
+
+func newStdlogSink() (hclog.Logger, *hclog.LoggerOptions) {
+	loggerOptions := &hclog.LoggerOptions{
+		IndependentLevels: true,
+		JSONFormat:        false,
+	}
+
+	return hclog.FromStandardLogger(log.Default(), loggerOptions), loggerOptions
+}