Refactor & more tests

Author: anisaoshafi

cmd/root.go

@@ -32,22 +32,15 @@ import (
 func NewRootCmd(cfg *env.Env, tel *telemetry.Client, logger log.Logger) *cobra.Command {
 	var firstRun bool
 	root := &cobra.Command{
-		Use:   "lstk",
-		Short: "LocalStack CLI",
-		Long:  "lstk is the command-line interface for LocalStack.",
-		PreRunE: func(cmd *cobra.Command, _ []string) error {
-			path, err := cmd.Flags().GetString("config")
+		Use:     "lstk",
+		Short:   "LocalStack CLI",
+		Long:    "lstk is the command-line interface for LocalStack.",
+		PreRunE: initConfigCapturingFirstRun(&firstRun),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			emulator, err := cmd.Flags().GetString("emulator")
 			if err != nil {
 				return err
 			}
-			if path != "" {
-				return config.InitFromPath(path)
-			}
-			firstRun, err = config.Init()
-			return err
-		},
-		RunE: func(cmd *cobra.Command, args []string) error {
-			emulator, _ := cmd.Flags().GetString("emulator")
 			rt, err := runtime.NewDockerRuntime(cfg.DockerHost)
 			if err != nil {
 				return err
@@ -355,3 +348,19 @@ func initConfig(cmd *cobra.Command, _ []string) error {
 	_, err = config.Init()
 	return err
 }
+
+// initConfigCapturingFirstRun returns a PreRunE that initialises config and
+// writes whether this is the first run into the provided pointer.
+func initConfigCapturingFirstRun(firstRun *bool) func(*cobra.Command, []string) error {
+	return func(cmd *cobra.Command, _ []string) error {
+		path, err := cmd.Flags().GetString("config")
+		if err != nil {
+			return err
+		}
+		if path != "" {
+			return config.InitFromPath(path)
+		}
+		*firstRun, err = config.Init()
+		return err
+	}
+}

cmd/start.go

@@ -1,7 +1,6 @@
 package cmd
 
 import (
-	"github.com/localstack/lstk/internal/config"
 	"github.com/localstack/lstk/internal/env"
 	"github.com/localstack/lstk/internal/log"
 	"github.com/localstack/lstk/internal/runtime"
@@ -12,22 +11,15 @@ import (
 func newStartCmd(cfg *env.Env, tel *telemetry.Client, logger log.Logger) *cobra.Command {
 	var firstRun bool
 	cmd := &cobra.Command{
-		Use:   "start",
-		Short: "Start emulator",
-		Long:  "Start emulator and services.",
-		PreRunE: func(c *cobra.Command, _ []string) error {
-			path, err := c.Flags().GetString("config")
+		Use:     "start",
+		Short:   "Start emulator",
+		Long:    "Start emulator and services.",
+		PreRunE: initConfigCapturingFirstRun(&firstRun),
+		RunE: func(c *cobra.Command, args []string) error {
+			emulator, err := c.Flags().GetString("emulator")
 			if err != nil {
 				return err
 			}
-			if path != "" {
-				return config.InitFromPath(path)
-			}
-			firstRun, err = config.Init()
-			return err
-		},
-		RunE: func(c *cobra.Command, args []string) error {
-			emulator, _ := c.Flags().GetString("emulator")
 			rt, err := runtime.NewDockerRuntime(cfg.DockerHost)
 			if err != nil {
 				return err

test/integration/emulator_select_test.go

@@ -0,0 +1,103 @@
+package integration_test
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"testing"
+	"time"
+
+	"github.com/creack/pty"
+	"github.com/localstack/lstk/test/integration/env"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// freshConfigEnv returns an Environ pointing HOME and USERPROFILE at a new
+// temp directory (with .config/ pre-created) so lstk uses an isolated config
+// dir on both Unix (HOME) and Windows (USERPROFILE).
+func freshConfigEnv(t *testing.T) (env.Environ, string) {
+	t.Helper()
+	tmpHome := t.TempDir()
+	require.NoError(t, os.MkdirAll(filepath.Join(tmpHome, ".config"), 0755))
+	return env.Without(env.Home).
+		With(env.Home, tmpHome).
+		With("USERPROFILE", tmpHome), tmpHome
+}
+
+func TestEmulatorFlagSwitchesConfigToSnowflake(t *testing.T) {
+	// config.SwitchEmulator writes the file before container.Start is called,
+	// so we can verify the switch even when the process ultimately fails (no Docker).
+	e, tmpHome := freshConfigEnv(t)
+
+	configDir := filepath.Join(tmpHome, ".config", "lstk")
+	require.NoError(t, os.MkdirAll(configDir, 0755))
+	configPath := filepath.Join(configDir, "config.toml")
+	require.NoError(t, os.WriteFile(configPath, []byte(`[[containers]]
+type = "aws"
+tag  = "latest"
+port = "4566"
+`), 0644))
+
+	ctx := testContext(t)
+	// The process will fail at container.Start (no Docker / no real auth), but the
+	// config switch happens earlier so the file should already be updated.
+	_, _, _ = runLstk(t, ctx, "", e.With(env.AuthToken, "test-token"), "--emulator", "snowflake", "--non-interactive")
+
+	got, err := os.ReadFile(configPath)
+	require.NoError(t, err, "config file should still exist after the run")
+	assert.Contains(t, string(got), `type = "snowflake"`, "config should be switched to snowflake")
+	assert.NotContains(t, string(got), "\n[[containers]]\ntype = \"aws\"", "original aws block should be commented out")
+}
+
+func TestFirstRunShowsEmulatorSelectionPrompt(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("PTY not supported on Windows")
+	}
+
+	// Fresh HOME with no lstk config — triggers first-run behaviour.
+	e, tmpHome := freshConfigEnv(t)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+
+	cmd := exec.CommandContext(ctx, binaryPath(), "start")
+	cmd.Env = e.With(env.AuthToken, "test-token")
+
+	ptmx, err := pty.Start(cmd)
+	require.NoError(t, err, "failed to start lstk in PTY")
+	defer func() { _ = ptmx.Close() }()
+
+	out := &syncBuffer{}
+	outputCh := make(chan struct{})
+	go func() {
+		_, _ = io.Copy(out, ptmx)
+		close(outputCh)
+	}()
+
+	require.Eventually(t, func() bool {
+		return bytes.Contains(out.Bytes(), []byte("Which emulator would you like to use?"))
+	}, 10*time.Second, 100*time.Millisecond, "emulator selection prompt should appear on first run")
+
+	// Choose Snowflake.
+	_, err = ptmx.Write([]byte("s"))
+	require.NoError(t, err)
+
+	require.Eventually(t, func() bool {
+		return bytes.Contains(out.Bytes(), []byte("Snowflake emulator selected"))
+	}, 5*time.Second, 100*time.Millisecond, "confirmation should appear after selection")
+
+	// Config is written before the confirmation is emitted, so it is safe to read now.
+	configPath := filepath.Join(tmpHome, ".config", "lstk", "config.toml")
+	got, err := os.ReadFile(configPath)
+	require.NoError(t, err, "config file should have been created on first run")
+	assert.Contains(t, string(got), `type = "snowflake"`)
+
+	// Kill the process — we do not need the emulator to actually start.
+	cancel()
+	<-outputCh
+}