Add winutil io tests

Signed-off-by: Justin Alvarez <[email protected]>

pkg/winutil/io_test.go

@@ -0,0 +1,119 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package winutil
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFromUTF16le(t *testing.T) {
+	testCases := []struct {
+		name         string
+		r            io.Reader
+		wantErr      error
+		postRunCheck func(t *testing.T, r io.Reader)
+	}{
+		{
+			name: "happy path",
+			r: bytes.NewBuffer([]byte{
+				// UTF16le BOM
+				0xff,
+				0xfe,
+				// Test\n
+				'T',
+				0x00,
+				'e',
+				0x00,
+				's',
+				0x00,
+				't',
+				0x00,
+				'\n',
+				0x00,
+			}),
+			postRunCheck: func(t *testing.T, r io.Reader) {
+				str, err := io.ReadAll(r)
+				require.NoError(t, err)
+				assert.Equal(t, []byte("Test\n"), str)
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			tc.postRunCheck(t, FromUTF16le(tc.r))
+		})
+	}
+}
+
+func TestFromUTF16leToString(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		name         string
+		r            io.Reader
+		postRunCheck func(t *testing.T, r string)
+		wantErr      error
+	}{
+		{
+			name: "happy path",
+			r: bytes.NewBuffer([]byte{
+				// UTF16le BOM
+				0xff,
+				0xfe,
+				// Test\n
+				'T',
+				0x00,
+				'e',
+				0x00,
+				's',
+				0x00,
+				't',
+				0x00,
+				'\n',
+				0x00,
+			}),
+			postRunCheck: func(t *testing.T, str string) {
+				assert.Equal(t, "Test\n", str)
+			},
+			wantErr: nil,
+		},
+		{
+			name:         "error reading buffer",
+			r:            NewErrorReader("read error!"),
+			postRunCheck: func(t *testing.T, str string) {},
+			wantErr:      errors.New("read error!"),
+		},
+	}
+
+	for _, tc := range testCases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			out, err := FromUTF16leToString(tc.r)
+			assert.Equal(t, tc.wantErr, err)
+			tc.postRunCheck(t, out)
+		})
+	}
+}
+
+type errReader struct {
+	errMsg string
+}
+
+func (er errReader) Read(p []byte) (n int, err error) {
+	return 0, errors.New(er.errMsg)
+}
+
+func NewErrorReader(errMsg string) errReader {
+	return errReader{errMsg: errMsg}
+}