feat: experiment taskfile envs take precedence over os envs (#1633)

* feat: experiment taskfile envs take precedence over os envs

* fix test

* fix typo

Co-authored-by: Andrey Nering <andrey@nering.com.br>

* docs: add p about default

---------

Co-authored-by: Andrey Nering <andrey@nering.com.br>

internal/env/env.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/go-task/task/v3/internal/experiments"
 	"github.com/go-task/task/v3/taskfile/ast"
 )
 
@@ -11,15 +12,15 @@ func Get(t *ast.Task) []string {
 	if t.Env == nil {
 		return nil
 	}
-
 	environ := os.Environ()
 	for k, v := range t.Env.ToCacheMap() {
 		if !isTypeAllowed(v) {
 			continue
 		}
-
-		if _, alreadySet := os.LookupEnv(k); alreadySet {
-			continue
+		if !experiments.EnvPrecedence.Enabled {
+			if _, alreadySet := os.LookupEnv(k); alreadySet {
+				continue
+			}
 		}
 		environ = append(environ, fmt.Sprintf("%s=%v", k, v))
 	}

internal/experiments/experiments.go

@@ -29,6 +29,7 @@ var (
 	RemoteTaskfiles Experiment
 	AnyVariables    Experiment
 	MapVariables    Experiment
+	EnvPrecedence   Experiment
 )
 
 func init() {
@@ -37,6 +38,7 @@ func init() {
 	RemoteTaskfiles = New("REMOTE_TASKFILES")
 	AnyVariables = New("ANY_VARIABLES", "1", "2")
 	MapVariables = New("MAP_VARIABLES", "1", "2")
+	EnvPrecedence = New("ENV_PRECEDENCE")
 }
 
 func New(xName string, enabledValues ...string) Experiment {
@@ -104,5 +106,6 @@ func List(l *logger.Logger) error {
 	printExperiment(w, l, GentleForce)
 	printExperiment(w, l, RemoteTaskfiles)
 	printExperiment(w, l, MapVariables)
+	printExperiment(w, l, EnvPrecedence)
 	return w.Flush()
 }