Add test demonstrating problem with ForEachLineInFile

The function drops the last line if it doesn't end with a line feed.

pkg/utils/io_test.go

@@ -0,0 +1,63 @@
+package utils
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_forEachLineInStream(t *testing.T) {
+	scenarios := []struct {
+		name          string
+		input         string
+		expectedLines []string
+	}{
+		{
+			name:          "empty input",
+			input:         "",
+			expectedLines: []string{},
+		},
+		{
+			name:          "single line",
+			input:         "abc\n",
+			expectedLines: []string{"abc\n"},
+		},
+		{
+			name:          "single line without line feed",
+			input:         "abc",
+			/* EXPECTED:
+			expectedLines: []string{"abc"},
+			ACTUAL: */
+			expectedLines: []string{},
+		},
+		{
+			name:          "multiple lines",
+			input:         "abc\ndef\n",
+			expectedLines: []string{"abc\n", "def\n"},
+		},
+		{
+			name:          "multiple lines including empty lines",
+			input:         "abc\n\ndef\n",
+			expectedLines: []string{"abc\n", "\n", "def\n"},
+		},
+		{
+			name:          "multiple lines without linefeed at end of file",
+			input:         "abc\ndef\nghi",
+			/* EXPECTED:
+			expectedLines: []string{"abc\n", "def\n", "ghi"},
+			ACTUAL: */
+			expectedLines: []string{"abc\n", "def\n"},
+		},
+	}
+
+	for _, s := range scenarios {
+		t.Run(s.name, func(t *testing.T) {
+			lines := []string{}
+			forEachLineInStream(strings.NewReader(s.input), func(line string, i int) {
+				lines = append(lines, line)
+			})
+			assert.EqualValues(t, s.expectedLines, lines)
+		})
+	}
+}