1 files changed, 54 insertions, 0 deletions
diff --git a/src/go/collectors/go.d.plugin/pkg/logs/lastline_test.go b/src/go/collectors/go.d.plugin/pkg/logs/lastline_test.go
new file mode 100644
index 000000000..ea0a75e9e
--- /dev/null
+++ b/src/go/collectors/go.d.plugin/pkg/logs/lastline_test.go
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package logs
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestReadLastLine(t *testing.T) {
+	tests := []struct {
+		name     string
+		content  string
+		expected string
+		err      error
+	}{
+		{"empty", "", "", nil},
+		{"empty-ln", "\n", "\n", nil},
+		{"one-line", "hello", "hello", nil},
+		{"one-line-ln", "hello\n", "hello\n", nil},
+		{"multi-line", "hello\nworld", "world", nil},
+		{"multi-line-ln", "hello\nworld\n", "world\n", nil},
+		{"long-line", "hello hello hello", "", ErrTooLongLine},
+		{"long-line-ln", "hello hello hello\n", "", ErrTooLongLine},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			filename := prepareFile(t, test.content)
+			defer func() { _ = os.Remove(filename) }()
+
+			line, err := ReadLastLine(filename, 10)
+
+			if test.err != nil {
+				require.NotNil(t, err)
+				assert.Contains(t, err.Error(), test.err.Error())
+			} else {
+				assert.Equal(t, test.expected, string(line))
+			}
+		})
+	}
+}
+
+func prepareFile(t *testing.T, content string) string {
+	t.Helper()
+	file, err := os.CreateTemp("", "go-test")
+	require.NoError(t, err)
+	defer func() { _ = file.Close() }()
+
+	_, _ = file.WriteString(content)
+	return file.Name()
+}