fix(edit): keep JSONC inserts out of leading comments (#639)

internal/edit/json.go

@@ -91,7 +91,7 @@ func splice(raw []byte, at, n int, with []byte) ([]byte, error) {
 // at or after position from.
 func insertKey(raw, stripped []byte, from int, key string, value any) ([]byte, error) {
 	open := from
-	for open < len(raw) && raw[open] != '{' {
+	for open < len(raw) && stripped[open] != '{' {
 		open++
 	}
 	close := matchBrace(stripped, open)

internal/edit/jsonc_comments_test.go

@@ -0,0 +1,133 @@
+package edit
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+
+	"github.com/tidwall/jsonc"
+)
+
+func TestJSONCLeadingCommentsKeepMembers(t *testing.T) {
+	object := "{\n  \"keep\": {\"nested\": \"original\"},\n  \"label\": \"stable\"\n}\n"
+	compact := `{"keep":{"nested":"original"},"label":"stable"}`
+	crlf := "{\r\n\t\"keep\": {\"nested\": \"原值\"},\r\n\t\"label\": \"stable\"\r\n}\r\n"
+	members := []string{`"nested": "original"`, `"label": "stable"`}
+	unchanged := map[string]string{"keep.nested": "original", "label": "stable"}
+	unicodeUnchanged := map[string]string{"keep.nested": "原值", "label": "stable"}
+	lineHeader := "// heading { brace stays in this comment\n"
+	blockHeader := "/* heading { brace stays in this comment */\n"
+	nestedInput := lineHeader + blockHeader + object
+
+	cases := []struct {
+		name      string
+		input     string
+		key       string
+		value     string
+		comments  []string
+		members   []string
+		unchanged map[string]string
+	}{
+		{
+			name: "plain_top_level_control", input: object, key: "added", value: "new",
+			members: members, unchanged: unchanged,
+		},
+		{
+			name: "line_header_brace", input: lineHeader + object, key: "added", value: "new",
+			comments: []string{strings.TrimSuffix(lineHeader, "\n")}, members: members, unchanged: unchanged,
+		},
+		{
+			name: "block_header_brace", input: blockHeader + object, key: "added", value: "new",
+			comments: []string{strings.TrimSuffix(blockHeader, "\n")}, members: members, unchanged: unchanged,
+		},
+		{
+			name: "compact_block_header_brace", input: "/* heading { brace */" + compact, key: "added", value: "new",
+			comments: []string{"/* heading { brace */"},
+			members:  []string{`"nested":"original"`, `"label":"stable"`}, unchanged: unchanged,
+		},
+		{
+			name: "tab_unicode_crlf_line_header_brace", input: "\t// 中文说明 { 保留\r\n" + crlf, key: "新增", value: "模型\t更新",
+			comments: []string{"\t// 中文说明 { 保留\r\n"},
+			members:  []string{"\t\"keep\": {\"nested\": \"原值\"},\r\n", "\t\"label\": \"stable\"\r\n"}, unchanged: unicodeUnchanged,
+		},
+		{
+			name: "tab_unicode_crlf_block_header_brace", input: "\t/* 中文说明 { 保留 */\r\n" + crlf, key: "新增", value: "模型\t更新",
+			comments: []string{"\t/* 中文说明 { 保留 */\r\n"},
+			members:  []string{"\t\"keep\": {\"nested\": \"原值\"},\r\n", "\t\"label\": \"stable\"\r\n"}, unchanged: unicodeUnchanged,
+		},
+		{
+			name: "empty_line_comment_object", input: "{\n  // inner { comment\n}\n", key: "added", value: "new",
+			comments: []string{"// inner { comment"},
+		},
+		{
+			name: "empty_block_comment_object", input: "{\n  /* inner { comment */\n}\n", key: "added", value: "new",
+			comments: []string{"/* inner { comment */"},
+		},
+		{
+			name: "compact_empty_block_comment_object", input: "{/* inner { comment */}", key: "added", value: "new",
+			comments: []string{"/* inner { comment */"},
+		},
+		{
+			name: "empty_object_line_header_brace", input: lineHeader + "{\n  // keep inner comment\n}\n", key: "added", value: "new",
+			comments: []string{strings.TrimSuffix(lineHeader, "\n"), "// keep inner comment"},
+		},
+		{
+			name: "empty_object_block_header_brace", input: blockHeader + "{\n  /* keep inner comment */\n}\n", key: "added", value: "new",
+			comments: []string{strings.TrimSuffix(blockHeader, "\n"), "/* keep inner comment */"},
+		},
+		{
+			name: "existing_nested_object_control", input: nestedInput, key: "keep.added", value: "new",
+			comments: []string{strings.TrimSuffix(lineHeader, "\n"), strings.TrimSuffix(blockHeader, "\n")},
+			members:  members, unchanged: unchanged,
+		},
+		{
+			name: "existing_nested_value_control", input: nestedInput, key: "keep.nested", value: "updated",
+			comments: []string{strings.TrimSuffix(lineHeader, "\n"), strings.TrimSuffix(blockHeader, "\n")},
+			members:  []string{`"label": "stable"`}, unchanged: map[string]string{"label": "stable"},
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			input := []byte(tc.input)
+			if !json.Valid(jsonc.ToJSON(append([]byte(nil), input...))) {
+				t.Fatalf("fixture is not valid JSONC: %q", tc.input)
+			}
+			path := tmpFile(t, "settings.jsonc", tc.input)
+			for key, want := range tc.unchanged {
+				if got, ok := GetJSON(path, key); !ok || got != want {
+					t.Fatalf("fixture GetJSON(%q) = %q, %v; want %q, true", key, got, ok, want)
+				}
+			}
+
+			if err := SetJSON(path, KV{Path: tc.key, Value: tc.value}); err != nil {
+				t.Fatalf("SetJSON on valid JSONC: %v", err)
+			}
+			output := []byte(read(t, path))
+			valid := json.Valid(jsonc.ToJSON(append([]byte(nil), output...)))
+			value, exists := GetJSON(path, tc.key)
+			t.Logf("SetJSON returned nil; json.Valid = %v; GetJSON(%q) = %q, %v; output = %q", valid, tc.key, value, exists, output)
+			if !valid {
+				t.Errorf("SetJSON produced invalid JSONC")
+			}
+			if !exists || value != tc.value {
+				t.Errorf("GetJSON(%q) = %q, %v; want %q, true", tc.key, value, exists, tc.value)
+			}
+			for _, comment := range tc.comments {
+				if !strings.Contains(string(output), comment) {
+					t.Errorf("original comment changed: %q", comment)
+				}
+			}
+			for _, member := range tc.members {
+				if !strings.Contains(string(output), member) {
+					t.Errorf("original member changed: %q", member)
+				}
+			}
+			for key, want := range tc.unchanged {
+				if got, ok := GetJSON(path, key); !ok || got != want {
+					t.Errorf("original GetJSON(%q) = %q, %v; want %q, true", key, got, ok, want)
+				}
+			}
+		})
+	}
+}