Merge pull request #8059 from hashicorp/tests-log-output

tests: log to stderr directly

helper/testlog/testlog.go

@@ -12,52 +12,26 @@ import (
 	hclog "github.com/hashicorp/go-hclog"
 )
 
-// UseStdout returns true if NOMAD_TEST_STDOUT=1 and sends logs to stdout.
-func UseStdout() bool {
-	return os.Getenv("NOMAD_TEST_STDOUT") == "1"
-}
-
 // LogPrinter is the methods of testing.T (or testing.B) needed by the test
 // logger.
 type LogPrinter interface {
 	Logf(format string, args ...interface{})
 }
 
-// writer implements io.Writer on top of a Logger.
-type writer struct {
-	prefix string
-	t      LogPrinter
-}
-
-// Write to an underlying Logger. Never returns an error.
-func (w *writer) Write(p []byte) (n int, err error) {
-	w.t.Logf("%s%s", w.prefix, p)
-	return len(p), nil
-}
-
 // NewWriter creates a new io.Writer backed by a Logger.
 func NewWriter(t LogPrinter) io.Writer {
-	if UseStdout() {
-		return os.Stdout
-	}
-	return &writer{t: t}
+	return os.Stderr
 }
 
 // NewPrefixWriter creates a new io.Writer backed by a Logger with a custom
 // prefix per Write.
 func NewPrefixWriter(t LogPrinter, prefix string) io.Writer {
-	if UseStdout() {
-		return &prefixStdout{[]byte(prefix)}
-	}
-	return &writer{prefix, t}
+	return &prefixStderr{[]byte(prefix)}
 }
 
 // New returns a new test logger. See https://golang.org/pkg/log/#New
 func New(t LogPrinter, prefix string, flag int) *log.Logger {
-	if UseStdout() {
-		return log.New(os.Stdout, prefix, flag)
-	}
-	return log.New(&writer{t: t}, prefix, flag)
+	return log.New(os.Stderr, prefix, flag)
 }
 
 // WithPrefix returns a new test logger with the Lmicroseconds flag set.
@@ -80,29 +54,29 @@ func HCLogger(t LogPrinter) hclog.InterceptLogger {
 	}
 	opts := &hclog.LoggerOptions{
 		Level:           level,
-		Output:          NewWriter(t),
+		Output:          os.Stderr,
 		IncludeLocation: true,
 	}
 	return hclog.NewInterceptLogger(opts)
 }
 
-type prefixStdout struct {
+type prefixStderr struct {
 	prefix []byte
 }
 
 // Write to stdout with a prefix per call containing non-whitespace characters.
-func (w *prefixStdout) Write(p []byte) (int, error) {
+func (w *prefixStderr) Write(p []byte) (int, error) {
 	if len(p) == 0 {
 		return 0, nil
 	}
 
 	// Skip prefix if only writing whitespace
 	if len(bytes.TrimSpace(p)) > 0 {
-		_, err := os.Stdout.Write(w.prefix)
+		_, err := os.Stderr.Write(w.prefix)
 		if err != nil {
 			return 0, err
 		}
 	}
 
-	return os.Stdout.Write(p)
+	return os.Stderr.Write(p)
 }