prefer pwsh on windows if found (#1942)

* prefer pwsh on windows if found

prefer bash over sh if found

One windows test no longer defines a default shell to test if it's pwsh

* add dep

---------

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Author: ChristopherHX

pkg/runner/step_run.go

@@ -3,12 +3,14 @@ package runner
 import (
 	"context"
 	"fmt"
+	"runtime"
 	"strings"
 
 	"github.com/kballard/go-shellquote"
 
 	"github.com/nektos/act/pkg/common"
 	"github.com/nektos/act/pkg/container"
+	"github.com/nektos/act/pkg/lookpath"
 	"github.com/nektos/act/pkg/model"
 )
 
@@ -138,6 +140,22 @@ func (sr *stepRun) setupShellCommand(ctx context.Context) (name, script string,
 	return name, script, err
 }
 
+type localEnv struct {
+	env map[string]string
+}
+
+func (l *localEnv) Getenv(name string) string {
+	if runtime.GOOS == "windows" {
+		for k, v := range l.env {
+			if strings.EqualFold(name, k) {
+				return v
+			}
+		}
+		return ""
+	}
+	return l.env[name]
+}
+
 func (sr *stepRun) setupShell(ctx context.Context) {
 	rc := sr.RunContext
 	step := sr.Step
@@ -152,13 +170,25 @@ func (sr *stepRun) setupShell(ctx context.Context) {
 		step.Shell = rc.Run.Workflow.Defaults.Run.Shell
 	}
 
-	// current GitHub Runner behaviour is that default is `sh`,
-	// but if it's not container it validates with `which` command
-	// if `bash` is available, and provides `bash` if it is
-	// for now I'm going to leave below logic, will address it in different PR
-	// https://github.com/actions/runner/blob/9a829995e02d2db64efb939dc2f283002595d4d9/src/Runner.Worker/Handlers/ScriptHandler.cs#L87-L91
-	if rc.Run.Job().Container() != nil {
-		if rc.Run.Job().Container().Image != "" && step.Shell == "" {
+	if step.Shell == "" {
+		if _, ok := rc.JobContainer.(*container.HostEnvironment); ok {
+			shellWithFallback := []string{"bash", "sh"}
+			// Don't use bash on windows by default, if not using a docker container
+			if runtime.GOOS == "windows" {
+				shellWithFallback = []string{"pwsh", "powershell"}
+			}
+			step.Shell = shellWithFallback[0]
+			lenv := &localEnv{env: map[string]string{}}
+			for k, v := range sr.env {
+				lenv.env[k] = v
+			}
+			sr.getRunContext().ApplyExtraPath(ctx, &lenv.env)
+			_, err := lookpath.LookPath2(shellWithFallback[0], lenv)
+			if err != nil {
+				step.Shell = shellWithFallback[1]
+			}
+		} else if containerImage := rc.containerImage(ctx); containerImage != "" {
+			// Currently only linux containers are supported, use sh by default like actions/runner
 			step.Shell = "sh"
 		}
 	}

pkg/runner/testdata/windows-add-env/push.yml

@@ -1,8 +1,5 @@
 on:
   push:
-defaults:
-  run:
-    shell: pwsh
 jobs:
   test:
     runs-on: windows-latest