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feat: implement autofix for no-unnormalized-keys #151

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17318be
feat: implement autofix for `no-unnormalized-keys`
lumirlumir Sep 20, 2025
4499d58
Merge branch 'main' into feat-support-autofix-for-no-unnormalized-keys
lumirlumir Sep 20, 2025
42c637a
wip
lumirlumir Sep 20, 2025
78c0ce5
wip: pin `rollup`
lumirlumir Sep 20, 2025
bd1dc6c
Merge branch 'main' into feat-support-autofix-for-no-unnormalized-keys
lumirlumir Oct 14, 2025
58a24c7
wip: add more test cases
lumirlumir Oct 14, 2025
1bfcd7d
wip
lumirlumir Oct 14, 2025
16a61a1
wip
lumirlumir Oct 14, 2025
5e5e7d8
wip: add more test
lumirlumir Oct 15, 2025
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22 changes: 15 additions & 7 deletions src/rules/no-unnormalized-keys.js
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,8 @@ const rule = {
meta: {
type: "problem",

fixable: "code",

docs: {
recommended: true,
description: "Disallow JSON keys that are not normalized",
Expand Down Expand Up @@ -57,19 +59,25 @@ const rule = {
const [{ form }] = context.options;

return {
Member(node) {
const key =
node.name.type === "String"
? node.name.value
: node.name.name;
Member({ name }) {
const key = name.type === "String" ? name.value : name.name;
const normalizedKey = key.normalize(form);

if (key.normalize(form) !== key) {
if (normalizedKey !== key) {
context.report({
loc: node.name.loc,
loc: name.loc,
messageId: "unnormalizedKey",
data: {
key,
},
fix(fixer) {
return fixer.replaceTextRange(
name.type === "String"
? [name.range[0] + 1, name.range[1] - 1]
: name.range,
normalizedKey,
);
},
Comment on lines +73 to +80
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@mdjermanovic mdjermanovic Oct 22, 2025

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This would produce incorrect fix if there are escape sequences, e.g., \n:

/* eslint json/no-unnormalized-keys: [2, { form: "NFD" }] */

{
    "\u1E9B\u0323\n": 42
}

Fixed to invalid JSON:

/* eslint json/no-unnormalized-keys: [2, { form: "NFD" }] */

{
    "ẛ̣
": 42
}

Also, I'm not sure if autofixing \u1E9B\u0323 to ẛ̣ instead of a sequence with \uXXXX would be desirable.

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@lumirlumir lumirlumir Oct 23, 2025

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Your suggestion also makes sense to me, but if that's the case, I have two questions:

  1. Should data.key be updated accordingly?

    It seems data.key is displayed the same way:
    image

  2. Is there a JavaScript (or other) rule I can refer to?

    I don't have much experience with JSON (and JavaScript) rules, so I think I'm missing some edge cases while implementing the rule. Do you have any recommendations I could refer to when implementing the rule? If so, that would be very helpful.

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@mdjermanovic mdjermanovic Oct 28, 2025

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  1. Should data.key be updated accordingly?

I think it would be better to show the raw key representation (i.e., as it appears in the linted source code) in the error message.

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@mdjermanovic mdjermanovic Oct 28, 2025

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2. Is there a JavaScript (or other) rule I can refer to?

I think the most similar thing we have in JS rules is a utility that parses string literals:

https://github.com/eslint/eslint/blob/main/lib/rules/utils/char-source.js

So we could try making something similar for JSON and use it to check how individual characters were represented in the original key and then try preserving the same form (a character directly inserted into the source code or an escape sequence) in the fixed key. A problem that might be difficult to solve in this particular rule is how to map characters from the fixed key to characters in the original key since the normalizations produce strings with different lengths.

Another option is to limit the autofix to keys that don't have escape sequences only.

});
}
},
Expand Down
150 changes: 150 additions & 0 deletions tests/rules/no-unnormalized-keys.test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,10 @@ const ruleTester = new RuleTester({
});

const o = "\u1E9B\u0323";
const escapedNfcO = "\\u1E9B\\u0323";
const escapedNfdO = "\\u017F\\u0323\\u0307";
const escapedNfkcO = "\\u1E69";
const escapedNfkdO = "\\u0073\\u0323\\u0307";

ruleTester.run("no-unnormalized-keys", rule, {
valid: [
Expand All @@ -43,10 +47,29 @@ ruleTester.run("no-unnormalized-keys", rule, {
code: `{"${o.normalize("NFKD")}":"NFKD"}`,
options: [{ form: "NFKD" }],
},
// escaped form
`{"${escapedNfcO}":"NFC"}`,
{
code: `{"${escapedNfcO}":"NFC"}`,
options: [{ form: "NFC" }],
},
{
code: `{"${escapedNfdO}":"NFD"}`,
options: [{ form: "NFD" }],
},
{
code: `{"${escapedNfkcO}":"NFKC"}`,
options: [{ form: "NFKC" }],
},
{
code: `{"${escapedNfkdO}":"NFKD"}`,
options: [{ form: "NFKD" }],
},
],
invalid: [
{
code: `{"${o.normalize("NFD")}":"NFD"}`,
output: `{"${o.normalize("NFC")}":"NFD"}`,
errors: [
{
messageId: "unnormalizedKey",
Expand All @@ -60,6 +83,7 @@ ruleTester.run("no-unnormalized-keys", rule, {
},
{
code: `{"${o.normalize("NFD")}":"NFD"}`,
output: `{"${o.normalize("NFC")}":"NFD"}`,
language: "json/jsonc",
errors: [
{
Expand All @@ -72,8 +96,39 @@ ruleTester.run("no-unnormalized-keys", rule, {
},
],
},
{
code: `{"${o.normalize("NFD")}":"NFD"}`,
output: `{"${o.normalize("NFC")}":"NFD"}`,
language: "json/json5",
errors: [
{
messageId: "unnormalizedKey",
data: { key: o.normalize("NFD") },
line: 1,
column: 2,
endLine: 1,
endColumn: 7,
},
],
},
{
code: `{'${o.normalize("NFD")}':'NFD'}`,
output: `{'${o.normalize("NFC")}':'NFD'}`,
language: "json/json5",
errors: [
{
messageId: "unnormalizedKey",
data: { key: o.normalize("NFD") },
line: 1,
column: 2,
endLine: 1,
endColumn: 7,
},
],
},
{
code: `{${o.normalize("NFD")}:"NFD"}`,
output: `{${o.normalize("NFC")}:"NFD"}`,
language: "json/json5",
errors: [
{
Expand All @@ -88,6 +143,23 @@ ruleTester.run("no-unnormalized-keys", rule, {
},
{
code: `{"${o.normalize("NFKC")}":"NFKC"}`,
output: `{"${o.normalize("NFKD")}":"NFKC"}`,
options: [{ form: "NFKD" }],
errors: [
{
messageId: "unnormalizedKey",
data: { key: o.normalize("NFKC") },
line: 1,
column: 2,
endLine: 1,
endColumn: 5,
},
],
},
{
code: `{"${o.normalize("NFKC")}":"NFKC"}`,
output: `{"${o.normalize("NFKD")}":"NFKC"}`,
language: "json/jsonc",
options: [{ form: "NFKD" }],
errors: [
{
Expand All @@ -100,5 +172,83 @@ ruleTester.run("no-unnormalized-keys", rule, {
},
],
},
{
code: `{"${o.normalize("NFKC")}":"NFKC"}`,
output: `{"${o.normalize("NFKD")}":"NFKC"}`,
language: "json/json5",
options: [{ form: "NFKD" }],
errors: [
{
messageId: "unnormalizedKey",
data: { key: o.normalize("NFKC") },
line: 1,
column: 2,
endLine: 1,
endColumn: 5,
},
],
},
{
code: `{'${o.normalize("NFKC")}':"NFKC"}`,
output: `{'${o.normalize("NFKD")}':"NFKC"}`,
language: "json/json5",
options: [{ form: "NFKD" }],
errors: [
{
messageId: "unnormalizedKey",
data: { key: o.normalize("NFKC") },
line: 1,
column: 2,
endLine: 1,
endColumn: 5,
},
],
},
{
code: `{${o.normalize("NFKC")}:"NFKC"}`,
output: `{${o.normalize("NFKD")}:"NFKC"}`,
language: "json/json5",
options: [{ form: "NFKD" }],
errors: [
{
messageId: "unnormalizedKey",
data: { key: o.normalize("NFKC") },
line: 1,
column: 2,
endLine: 1,
endColumn: 3,
},
],
},
// escaped form
{
code: `{"${escapedNfdO}":"NFD"}`,
output: `{"${o.normalize("NFC")}":"NFD"}`,
errors: [
{
messageId: "unnormalizedKey",
data: { key: o.normalize("NFD") },
line: 1,
column: 2,
endLine: 1,
endColumn: 22,
},
],
},
{
code: `{"${escapedNfkcO}":"NFKC"}`,
output: `{"${o.normalize("NFKD")}":"NFKC"}`,
options: [{ form: "NFKD" }],
errors: [
{
messageId: "unnormalizedKey",
data: { key: o.normalize("NFKC") },
line: 1,
column: 2,
endLine: 1,
endColumn: 10,
},
],
},
],
});