fix(process): handle zero-capacity ring buffers

buffer.go

@@ -15,6 +15,9 @@ type RingBuffer struct {
 
 // NewRingBuffer creates a ring buffer with the given capacity.
 func NewRingBuffer(size int) *RingBuffer {
+	if size < 0 {
+		size = 0
+	}
 	return &RingBuffer{
 		data: make([]byte, size),
 		size: size,
@@ -26,6 +29,10 @@ func (rb *RingBuffer) Write(p []byte) (n int, err error) {
 	rb.mu.Lock()
 	defer rb.mu.Unlock()
 
+	if rb.size == 0 {
+		return len(p), nil
+	}
+
 	for _, b := range p {
 		rb.data[rb.end] = b
 		rb.end = (rb.end + 1) % rb.size

buffer_test.go

@@ -69,4 +69,18 @@ func TestRingBuffer(t *testing.T) {
 		bytes[0] = 'x'
 		assert.Equal(t, "hello", rb.String())
 	})
+
+	t.Run("zero or negative capacity is a no-op", func(t *testing.T) {
+		for _, size := range []int{0, -1} {
+			rb := NewRingBuffer(size)
+
+			n, err := rb.Write([]byte("discarded"))
+			assert.NoError(t, err)
+			assert.Equal(t, len("discarded"), n)
+			assert.Equal(t, 0, rb.Cap())
+			assert.Equal(t, 0, rb.Len())
+			assert.Equal(t, "", rb.String())
+			assert.Nil(t, rb.Bytes())
+		}
+	})
 }