1 files changed, 49 insertions, 0 deletions
diff --git a/internal/iohelpers/readers_test.go b/internal/iohelpers/readers_test.go
new file mode 100644
index 00000000..ef300ef8
--- /dev/null
+++ b/internal/iohelpers/readers_test.go
@@ -0,0 +1,49 @@
+package iohelpers
+
+import (
+	"bytes"
+	"io"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestLazyReadCloser(t *testing.T) {
+	r := newBufferCloser(bytes.NewBufferString("hello world"))
+	opened := false
+	l, ok := LazyReadCloser(func() (io.ReadCloser, error) {
+		opened = true
+		return r, nil
+	}).(*lazyReadCloser)
+	assert.True(t, ok)
+
+	assert.False(t, opened)
+	assert.Nil(t, l.r)
+	assert.False(t, r.closed)
+
+	p := make([]byte, 5)
+	n, err := l.Read(p)
+	assert.NoError(t, err)
+	assert.True(t, opened)
+	assert.Equal(t, r, l.r)
+	assert.Equal(t, 5, n)
+
+	err = l.Close()
+	assert.NoError(t, err)
+	assert.True(t, r.closed)
+
+	// test error propagation
+	l = LazyReadCloser(func() (io.ReadCloser, error) {
+		return nil, os.ErrNotExist
+	}).(*lazyReadCloser)
+
+	assert.Nil(t, l.r)
+
+	p = make([]byte, 5)
+	_, err = l.Read(p)
+	assert.Error(t, err)
+
+	err = l.Close()
+	assert.Error(t, err)
+}