Fix concurrent writes to stdout in tests.

executor.go

@@ -71,6 +71,7 @@ type (
 		executionHashes      map[string]context.Context
 		executionHashesMutex sync.Mutex
 		watchedDirs          *xsync.MapOf[string, bool]
+		stdoutMutex          sync.Mutex
 	}
 	TempDir struct {
 		Remote      string

task.go

@@ -1,6 +1,7 @@
 package task
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"os"
@@ -341,7 +342,10 @@ func (e *Executor) runCommand(ctx context.Context, t *ast.Task, call *Call, i in
 		if err != nil {
 			return fmt.Errorf("task: failed to get variables: %w", err)
 		}
-		stdOut, stdErr, closer := outputWrapper.WrapWriter(e.Stdout, e.Stderr, t.Prefix, outputTemplater)
+		// Capture stdout to a buffer because when run from a go routine (i.e. deps)
+		// then concurrent writes may occur on the shared e.Stdout.
+		_stdout := bytes.NewBuffer([]byte{})
+		stdOut, stdErr, closer := outputWrapper.WrapWriter(_stdout, e.Stderr, t.Prefix, outputTemplater)
 
 		err = execext.RunCommand(ctx, &execext.RunCommandOptions{
 			Command:   cmd.Cmd,
@@ -353,9 +357,17 @@ func (e *Executor) runCommand(ctx context.Context, t *ast.Task, call *Call, i in
 			Stdout:    stdOut,
 			Stderr:    stdErr,
 		})
+		// Calling closer will copy remaining buffered stdOut to _stdout. Then
+		// use a mutex to prevents concurant writes to e.Stdout.
+		e.stdoutMutex.Lock()
 		if closeErr := closer(err); closeErr != nil {
 			e.Logger.Errf(logger.Red, "task: unable to close writer: %v\n", closeErr)
 		}
+		if _, writeErr := e.Stdout.Write(_stdout.Bytes()); writeErr != nil {
+			e.Logger.Errf(logger.Red, "task: unable to write to e.Stdout: %v\n", writeErr)
+		}
+		e.stdoutMutex.Unlock()
+
 		var exitCode interp.ExitStatus
 		if errors.As(err, &exitCode) && cmd.IgnoreError {
 			e.Logger.VerboseErrf(logger.Yellow, "task: [%s] command error ignored: %v\n", t.Name(), err)