read gzip archives

internal/tartest/tartest.go

@@ -3,6 +3,8 @@ package tartest
 import (
 	"archive/tar"
 	"bytes"
+	"compress/gzip"
+	"fmt"
 	"io"
 	"testing"
 
@@ -53,6 +55,20 @@ func (tb Tarball) Buffer() *bytes.Buffer {
 	return &buf
 }
 
+// Gzip returns a gzipped buffer
+func (tb Tarball) Gzip() *bytes.Buffer {
+	var buf bytes.Buffer
+	w := gzip.NewWriter(&buf)
+	_, err := io.Copy(w, tb.Buffer())
+	if err != nil {
+		panic(fmt.Errorf("Gzip(): %w", err))
+	}
+	if err := w.Close(); err != nil {
+		panic(fmt.Errorf("gzip.Close(): %w", err))
+	}
+	return &buf
+}
+
 // Tar tars the Dir
 func (d Dir) Tar(tw *tar.Writer) error {
 	hdr := &tar.Header{

internal/tartest/tartest_test.go

@@ -2,9 +2,12 @@ package tartest
 
 import (
 	"bytes"
+	"compress/gzip"
+	"io"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestTarball(t *testing.T) {
@@ -23,6 +26,18 @@ func TestTarball(t *testing.T) {
 		Dir{Name: "bin"},
 		Hardlink{Name: "entrypoint2"},
 	}
-
 	assert.Equal(t, want, got)
 }
+
+func TestGzip(t *testing.T) {
+	tb := Tarball{File{Name: "entrypoint.sh", Contents: bytes.NewBufferString("hello")}}
+	tbuf := tb.Buffer()
+
+	tgz, err := gzip.NewReader(tb.Gzip())
+	require.NoError(t, err)
+	var uncompressed bytes.Buffer
+	_, err = io.Copy(&uncompressed, tgz)
+	require.NoError(t, err)
+	assert.Equal(t, tbuf.Bytes(), uncompressed.Bytes())
+
+}