fix: preserve stdin taskfile bytes (#2950)

Signed-off-by: cuishuang <imcusg@gmail.com>

taskfile/node_stdin_test.go

@@ -0,0 +1,65 @@
+package taskfile
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestStdinNodeReadPreservesInput(t *testing.T) { //nolint:paralleltest // replaces process-wide stdin
+	node, err := NewStdinNode("")
+	require.NoError(t, err)
+
+	tests := []struct {
+		name  string
+		input []byte
+	}{
+		{
+			name:  "line longer than 64 KiB",
+			input: []byte(strings.Repeat("a", 64*1024+1)),
+		},
+		{
+			name:  "no trailing newline",
+			input: []byte("version: '3'"),
+		},
+		{
+			name:  "CRLF line endings",
+			input: []byte("version: '3'\r\ntasks:\r\n"),
+		},
+		{
+			name:  "empty input",
+			input: []byte{},
+		},
+	}
+
+	for _, tt := range tests { //nolint:paralleltest // subtests replace process-wide stdin
+		t.Run(tt.name, func(t *testing.T) {
+			replaceStdin(t, tt.input)
+
+			got, err := node.Read()
+			require.NoError(t, err)
+			assert.Equal(t, tt.input, got)
+		})
+	}
+}
+
+func replaceStdin(t *testing.T, input []byte) {
+	t.Helper()
+
+	path := filepath.Join(t.TempDir(), "stdin")
+	require.NoError(t, os.WriteFile(path, input, 0o600))
+
+	stdin, err := os.Open(path)
+	require.NoError(t, err)
+
+	original := os.Stdin
+	os.Stdin = stdin
+	t.Cleanup(func() {
+		os.Stdin = original
+		require.NoError(t, stdin.Close())
+	})
+}