improve error message and check if powershell is installed

cli/azd/pkg/tools/powershell/powershell.go

@@ -5,29 +5,63 @@ package powershell
 
 import (
 	"context"
+	"fmt"
+	"strings"
 
+	"github.com/azure/azure-dev/cli/azd/internal"
 	"github.com/azure/azure-dev/cli/azd/pkg/exec"
+	"github.com/azure/azure-dev/cli/azd/pkg/output"
 	"github.com/azure/azure-dev/cli/azd/pkg/tools"
 )
 
 // Creates a new PowershellScript command runner
 func NewPowershellScript(commandRunner exec.CommandRunner, cwd string, envVars []string) tools.Script {
 	return &powershellScript{
-		commandRunner: commandRunner,
-		cwd:           cwd,
-		envVars:       envVars,
+		commandRunner:  commandRunner,
+		cwd:            cwd,
+		envVars:        envVars,
+		checkInstalled: checkPath,
+	}
+}
+
+// for testing
+func NewPowershellScriptWithMockCheckPath(
+	commandRunner exec.CommandRunner,
+	cwd string,
+	envVars []string,
+	mockCheckPath checkInstalled) tools.Script {
+	return &powershellScript{
+		commandRunner:  commandRunner,
+		cwd:            cwd,
+		envVars:        envVars,
+		checkInstalled: mockCheckPath,
 	}
 }
 
 type powershellScript struct {
-	commandRunner exec.CommandRunner
-	cwd           string
-	envVars       []string
+	commandRunner  exec.CommandRunner
+	cwd            string
+	envVars        []string
+	checkInstalled checkInstalled
+}
+
+type checkInstalled func(options tools.ExecOptions) error
+
+func checkPath(options tools.ExecOptions) (err error) {
+	return tools.ToolInPath(strings.Split(options.UserPwsh, " ")[0])
 }
 
 // Executes the specified powershell script
 // When interactive is true will attach to stdin, stdout & stderr
 func (bs *powershellScript) Execute(ctx context.Context, path string, options tools.ExecOptions) (exec.RunResult, error) {
+	if err := bs.checkInstalled(options); err != nil {
+		return exec.RunResult{}, &internal.ErrorWithSuggestion{
+			Err: err,
+			Suggestion: fmt.Sprintf("PowerShell 7 is not installed or not in the path. To install PowerShell 7, visit %s",
+				output.WithLinkFormat("https://learn.microsoft.com/powershell/scripting/install/installing-powershell")),
+		}
+	}
+
 	runArgs := exec.NewRunArgs(options.UserPwsh, path).
 		WithCwd(bs.cwd).
 		WithEnv(bs.envVars).

cli/azd/pkg/tools/powershell/powershell_test.go

@@ -6,6 +6,7 @@ package powershell
 import (
 	"context"
 	"errors"
+	"strings"
 	"testing"
 
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore/to"
@@ -29,7 +30,7 @@ func Test_Powershell_Execute(t *testing.T) {
 		// #nosec G101
 		userPwsh := "pwsh -NoProfile"
 		mockContext.CommandRunner.When(func(args exec.RunArgs, command string) bool {
-			return true
+			return strings.Contains(args.Cmd, userPwsh)
 		}).RespondFn(func(args exec.RunArgs) (exec.RunResult, error) {
 			require.Equal(t, userPwsh, args.Cmd)
 			require.Equal(t, workingDir, args.Cwd)
@@ -39,7 +40,13 @@ func Test_Powershell_Execute(t *testing.T) {
 			return exec.NewRunResult(0, "", ""), nil
 		})
 
-		PowershellScript := NewPowershellScript(mockContext.CommandRunner, workingDir, env)
+		PowershellScript := NewPowershellScriptWithMockCheckPath(
+			mockContext.CommandRunner,
+			workingDir,
+			env,
+			func(options tools.ExecOptions) error {
+				return nil
+			})
 		runResult, err := PowershellScript.Execute(
 			*mockContext.Context,
 			scriptPath,
@@ -59,7 +66,13 @@ func Test_Powershell_Execute(t *testing.T) {
 			return exec.NewRunResult(1, "", "error message"), errors.New("error message")
 		})
 
-		PowershellScript := NewPowershellScript(mockContext.CommandRunner, workingDir, env)
+		PowershellScript := NewPowershellScriptWithMockCheckPath(
+			mockContext.CommandRunner,
+			workingDir,
+			env,
+			func(options tools.ExecOptions) error {
+				return nil
+			})
 		runResult, err := PowershellScript.Execute(
 			*mockContext.Context,
 			scriptPath,
@@ -70,6 +83,19 @@ func Test_Powershell_Execute(t *testing.T) {
 		require.Error(t, err)
 	})
 
+	t.Run("NoPowerShellInstalled", func(t *testing.T) {
+		mockContext := mocks.NewMockContext(context.Background())
+
+		PowershellScript := NewPowershellScript(mockContext.CommandRunner, workingDir, env)
+		_, err := PowershellScript.Execute(
+			*mockContext.Context,
+			scriptPath,
+			tools.ExecOptions{Interactive: to.Ptr(true)},
+		)
+
+		require.Error(t, err)
+	})
+
 	tests := []struct {
 		name  string
 		value tools.ExecOptions
@@ -89,7 +115,13 @@ func Test_Powershell_Execute(t *testing.T) {
 				return exec.NewRunResult(0, "", ""), nil
 			})
 
-			PowershellScript := NewPowershellScript(mockContext.CommandRunner, workingDir, env)
+			PowershellScript := NewPowershellScriptWithMockCheckPath(
+				mockContext.CommandRunner,
+				workingDir,
+				env,
+				func(options tools.ExecOptions) error {
+					return nil
+				})
 			runResult, err := PowershellScript.Execute(*mockContext.Context, scriptPath, test.value)
 
 			require.NotNil(t, runResult)