Fix patch YAML without new line on end of file

pkg/yaml/yaml.go

@@ -109,6 +109,13 @@ func AddOrReplace(src []byte, key string, value any, nodeParent *yaml.Node) ([]b
 		i0 := LineOffset(src, nodeKey.Line)
 		i1 := LineOffset(src, LastChild(nodeValue).Line+1)
 
+		if i1 < 0 { // no new line on the end of file
+			if value != nil {
+				return append(src[:i0], put...), nil
+			}
+			return src[:i0], nil
+		}
+
 		dst := make([]byte, 0, len(src)+len(put))
 		dst = append(dst, src[:i0]...)
 		if value != nil {
@@ -121,6 +128,14 @@ func AddOrReplace(src []byte, key string, value any, nodeParent *yaml.Node) ([]b
 
 	i := LineOffset(src, LastChild(nodeParent).Line+1)
 
+	if i < 0 { // no new line on the end of file
+		src = append(src, '\n')
+		if value != nil {
+			src = append(src, put...)
+		}
+		return src, nil
+	}
+
 	dst := make([]byte, 0, len(src)+len(put))
 	dst = append(dst, src[:i]...)
 	if value != nil {

pkg/yaml/yaml_test.go

@@ -104,3 +104,43 @@ func TestPatch2(t *testing.T) {
   camera2: url3
 `, string(b))
 }
+
+func TestNoNewLineEnd1(t *testing.T) {
+	b := []byte(`streams:
+  camera1: url4
+  camera2:
+    - url2
+    - url3`)
+
+	b, err := Patch(b, "camera2", "url5", "streams")
+	require.Nil(t, err)
+
+	require.Equal(t, `streams:
+  camera1: url4
+  camera2: url5
+`, string(b))
+}
+
+func TestNoNewLineEnd2(t *testing.T) {
+	b := []byte(`streams:
+  camera1: url1
+homekit:
+  camera1:
+    pin: 123-45-678`)
+
+	// 1. Add new key
+	pairings := []string{"client1", "client2"}
+
+	b, err := Patch(b, "pairings", pairings, "homekit", "camera1")
+	require.Nil(t, err)
+
+	require.Equal(t, `streams:
+  camera1: url1
+homekit:
+  camera1:
+    pin: 123-45-678
+    pairings:
+      - client1
+      - client2
+`, string(b))
+}