allow custom Stdin, Stdout and Stderr while running as a lib

cmd/task/task.go

@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"log"
+	"os"
 
 	"github.com/go-task/task"
 
@@ -61,6 +62,10 @@ hello:
 	e := task.Executor{
 		Force: force,
 		Watch: watch,
+
+		Stdin:  os.Stdin,
+		Stdout: os.Stdout,
+		Stderr: os.Stderr,
 	}
 	if err := e.ReadTaskfile(); err != nil {
 		log.Fatal(err)

help.go

@@ -2,7 +2,6 @@ package task
 
 import (
 	"fmt"
-	"os"
 	"sort"
 	"text/tabwriter"
 )
@@ -12,10 +11,10 @@ func (e *Executor) printExistingTasksHelp() {
 	if len(tasks) == 0 {
 		return
 	}
-	fmt.Println("Available tasks for this project:")
+	e.println("Available tasks for this project:")
 
 	// Format in tab-separated columns with a tab stop of 8.
-	w := tabwriter.NewWriter(os.Stdout, 0, 8, 0, '\t', 0)
+	w := tabwriter.NewWriter(e.Stdout, 0, 8, 0, '\t', 0)
 	for _, task := range tasks {
 		fmt.Fprintln(w, fmt.Sprintf("- %s:\t%s", task, e.Tasks[task].Desc))
 	}

log.go

@@ -0,0 +1,13 @@
+package task
+
+import (
+	"fmt"
+)
+
+func (e *Executor) println(args ...interface{}) {
+	fmt.Fprintln(e.Stdout, args...)
+}
+
+func (e *Executor) printfln(format string, args ...interface{}) {
+	fmt.Fprintf(e.Stdout, format+"\n", args...)
+}

task.go

@@ -4,7 +4,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
-	"log"
+	"io"
 	"os"
 	"path/filepath"
 	"strings"
@@ -26,6 +26,10 @@ type Executor struct {
 	Force bool
 	Watch bool
 
+	Stdin  io.Reader
+	Stdout io.Writer
+	Stderr io.Writer
+
 	watchingFiles map[string]struct{}
 }
 
@@ -52,6 +56,16 @@ func (e *Executor) Run(args ...string) error {
 		return ErrCyclicDependencyDetected
 	}
 
+	if e.Stdin == nil {
+		e.Stdin = os.Stdin
+	}
+	if e.Stdout == nil {
+		e.Stdout = os.Stdout
+	}
+	if e.Stderr == nil {
+		e.Stderr = os.Stderr
+	}
+
 	// check if given tasks exist
 	for _, a := range args {
 		if _, ok := e.Tasks[a]; !ok {
@@ -93,7 +107,7 @@ func (e *Executor) RunTask(ctx context.Context, name string) error {
 			return err
 		}
 		if upToDate {
-			log.Printf(`task: Task "%s" is up to date`, name)
+			e.printfln(`task: Task "%s" is up to date`, name)
 			return nil
 		}
 	}
@@ -231,13 +245,13 @@ func (e *Executor) runCommand(ctx context.Context, task string, i int) error {
 		Command: c,
 		Dir:     dir,
 		Env:     envs,
-		Stdin:   os.Stdin,
-		Stderr:  os.Stderr,
+		Stdin:   e.Stdin,
+		Stderr:  e.Stderr,
 	}
 
 	if t.Set == "" {
-		log.Println(c)
-		opts.Stdout = os.Stdout
+		e.println(c)
+		opts.Stdout = e.Stdout
 		if err = execext.RunCommand(opts); err != nil {
 			return err
 		}

variable_handling.go

@@ -36,7 +36,7 @@ func (e *Executor) handleDynamicVariableContent(value string) (string, error) {
 		Command: strings.TrimPrefix(value, "$"),
 		Dir:     e.Dir,
 		Stdout:  buff,
-		Stderr:  os.Stderr,
+		Stderr:  e.Stderr,
 	}
 	if err := execext.RunCommand(opts); err != nil {
 		return "", err

watch.go

@@ -2,8 +2,6 @@ package task
 
 import (
 	"context"
-	"fmt"
-	"log"
 	"strings"
 	"time"
 
@@ -13,12 +11,12 @@ import (
 
 // watchTasks start watching the given tasks
 func (e *Executor) watchTasks(args ...string) error {
-	log.Printf("task: Started watching for tasks: %s", strings.Join(args, ", "))
+	e.printfln("task: Started watching for tasks: %s", strings.Join(args, ", "))
 
 	// run tasks on init
 	for _, a := range args {
 		if err := e.RunTask(context.Background(), a); err != nil {
-			fmt.Println(err)
+			e.println(err)
 			break
 		}
 	}
@@ -32,7 +30,7 @@ func (e *Executor) watchTasks(args ...string) error {
 	go func() {
 		for {
 			if err := e.registerWatchedFiles(watcher, args); err != nil {
-				log.Printf("Error watching files: %v", err)
+				e.printfln("Error watching files: %v", err)
 			}
 			time.Sleep(time.Second * 2)
 		}
@@ -44,12 +42,12 @@ loop:
 		case <-watcher.Events:
 			for _, a := range args {
 				if err := e.RunTask(context.Background(), a); err != nil {
-					fmt.Println(err)
+					e.println(err)
 					continue loop
 				}
 			}
 		case err := <-watcher.Errors:
-			fmt.Println(err)
+			e.println(err)
 			continue loop
 		}
 	}