refactor: Maintain single code path for package manager execution (#256)

* refactor: Maintain single code path for package manager execution

* fix: Avoid context leak during interactive TTY read

* fix: PTY flow handling

* fix: Linter fixes

internal/pty/router_test.go

@@ -0,0 +1,84 @@
+//go:build !windows
+
+package pty
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestInputRouterReadLoopContextStopsOnCancelForFileReader(t *testing.T) {
+	reader, writer, err := os.Pipe()
+	require.NoError(t, err)
+	defer func() {
+		require.NoError(t, reader.Close())
+	}()
+	defer func() {
+		require.NoError(t, writer.Close())
+	}()
+
+	router, err := NewInputRouter(&bytes.Buffer{})
+	require.NoError(t, err)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		router.ReadLoopContext(ctx, reader)
+	}()
+
+	cancel()
+
+	require.Eventually(t, func() bool {
+		select {
+		case <-done:
+			return true
+		default:
+			return false
+		}
+	}, time.Second, 10*time.Millisecond)
+}
+
+func TestInputRouterReadLoopContextStopsOnWriteError(t *testing.T) {
+	reader, writer, err := os.Pipe()
+	require.NoError(t, err)
+	defer func() {
+		require.NoError(t, reader.Close())
+	}()
+	defer func() {
+		require.NoError(t, writer.Close())
+	}()
+
+	router, err := NewInputRouter(errorWriter{})
+	require.NoError(t, err)
+
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		router.ReadLoopContext(context.Background(), reader)
+	}()
+
+	_, err = writer.Write([]byte("x"))
+	require.NoError(t, err)
+
+	require.Eventually(t, func() bool {
+		select {
+		case <-done:
+			return true
+		default:
+			return false
+		}
+	}, time.Second, 10*time.Millisecond)
+}
+
+type errorWriter struct{}
+
+func (errorWriter) Write(_ []byte) (int, error) {
+	return 0, errors.New("write failed")
+}