diff --git a/tests/format/js/_errors_/for-in-invalid-initializer/__snapshots__/format.test.js.snap b/tests/format/js/_errors_/for-in-invalid-initializer/__snapshots__/format.test.js.snap
new file mode 100644
index 000000000..f9a569f8b
--- /dev/null
+++ b/tests/format/js/_errors_/for-in-invalid-initializer/__snapshots__/format.test.js.snap
@@ -0,0 +1,169 @@
+// Jest Snapshot v1, https://jestjs.io/docs/snapshot-testing
+
+exports[`snippet: #0 format[acorn] 1`] = `
+"for-in loop variable declaration may not have an initializer (1:6)
+> 1 | for (let a = 1 in b);
+    |      ^
+Cause: for-in loop variable declaration may not have an initializer (1:5)"
+`;
+
+exports[`snippet: #0 format[espree] 1`] = `
+"for-in loop variable declaration may not have an initializer (1:6)
+> 1 | for (let a = 1 in b);
+    |      ^
+Cause: for-in loop variable declaration may not have an initializer"
+`;
+
+exports[`snippet: #0 format[flow] 1`] = `
+"Invalid left-hand side in for-in (1:6)
+> 1 | for (let a = 1 in b);
+    |      ^
+Cause: Invalid left-hand side in for-in (1:5)"
+`;
+
+exports[`snippet: #0 format[hermes] 1`] = `
+"for-in/for-of variable declaration may not be initialized (1:14)
+> 1 | for (let a = 1 in b);
+    |              ^
+Cause: for-in/for-of variable declaration may not be initialized (1:13)
+for (let a = 1 in b);
+             ^"
+`;
+
+exports[`snippet: #0 format[meriyah] 1`] = `
+"'for-in' loop head declarations can not have an initializer (1:10)
+> 1 | for (let a = 1 in b);
+    |          ^^^^^^^^
+Cause: [1:9-1:17]: 'for-in' loop head declarations can not have an initializer"
+`;
+
+exports[`snippet: #0 format[oxc] 1`] = `
+"for-in loop variable declaration may not have an initializer (1:6)
+> 1 | for (let a = 1 in b);
+    |      ^^^^^^^^^"
+`;
+
+exports[`snippet: #0 format[oxc-ts] 1`] = `
+"for-in loop variable declaration may not have an initializer (1:6)
+> 1 | for (let a = 1 in b);
+    |      ^^^^^^^^^"
+`;
+
+exports[`snippet: #0 format[typescript] 1`] = `
+"The variable declaration of a 'for...in' statement cannot have an initializer. (1:10)
+> 1 | for (let a = 1 in b);
+    |          ^^^^^
+Cause: The variable declaration of a 'for...in' statement cannot have an initializer."
+`;
+
+exports[`snippet: #1 format[acorn] 1`] = `
+"for-in loop variable declaration may not have an initializer (1:6)
+> 1 | for (const a = 1 in b);
+    |      ^
+Cause: for-in loop variable declaration may not have an initializer (1:5)"
+`;
+
+exports[`snippet: #1 format[espree] 1`] = `
+"for-in loop variable declaration may not have an initializer (1:6)
+> 1 | for (const a = 1 in b);
+    |      ^
+Cause: for-in loop variable declaration may not have an initializer"
+`;
+
+exports[`snippet: #1 format[flow] 1`] = `
+"Invalid left-hand side in for-in (1:6)
+> 1 | for (const a = 1 in b);
+    |      ^
+Cause: Invalid left-hand side in for-in (1:5)"
+`;
+
+exports[`snippet: #1 format[hermes] 1`] = `
+"for-in/for-of variable declaration may not be initialized (1:16)
+> 1 | for (const a = 1 in b);
+    |                ^
+Cause: for-in/for-of variable declaration may not be initialized (1:15)
+for (const a = 1 in b);
+               ^"
+`;
+
+exports[`snippet: #1 format[meriyah] 1`] = `
+"'for-in' loop head declarations can not have an initializer (1:12)
+> 1 | for (const a = 1 in b);
+    |            ^^^^^^^^
+Cause: [1:11-1:19]: 'for-in' loop head declarations can not have an initializer"
+`;
+
+exports[`snippet: #1 format[oxc] 1`] = `
+"for-in loop variable declaration may not have an initializer (1:6)
+> 1 | for (const a = 1 in b);
+    |      ^^^^^^^^^^^"
+`;
+
+exports[`snippet: #1 format[oxc-ts] 1`] = `
+"for-in loop variable declaration may not have an initializer (1:6)
+> 1 | for (const a = 1 in b);
+    |      ^^^^^^^^^^^"
+`;
+
+exports[`snippet: #1 format[typescript] 1`] = `
+"The variable declaration of a 'for...in' statement cannot have an initializer. (1:12)
+> 1 | for (const a = 1 in b);
+    |            ^^^^^
+Cause: The variable declaration of a 'for...in' statement cannot have an initializer."
+`;
+
+exports[`snippet: #2 format[acorn] 1`] = `
+"for-in loop variable declaration may not have an initializer (1:7)
+> 1 | {for (using a = 1 in b);}
+    |       ^
+Cause: for-in loop variable declaration may not have an initializer (1:6)"
+`;
+
+exports[`snippet: #2 format[espree] 1`] = `
+"for-in loop variable declaration may not have an initializer (1:7)
+> 1 | {for (using a = 1 in b);}
+    |       ^
+Cause: for-in loop variable declaration may not have an initializer"
+`;
+
+exports[`snippet: #2 format[flow] 1`] = `
+"Unexpected identifier, expected the token \`;\` (1:13)
+> 1 | {for (using a = 1 in b);}
+    |             ^
+Cause: Unexpected identifier, expected the token \`;\` (1:12)"
+`;
+
+exports[`snippet: #2 format[hermes] 1`] = `
+"';' or 'in' expected inside 'for' (1:15)
+> 1 | {for (using a = 1 in b);}
+    |               ^
+Cause: ';' or 'in' expected inside 'for' (1:14)
+{for (using a = 1 in b);}
+ ~~~~~~~~~~~~~^"
+`;
+
+exports[`snippet: #2 format[meriyah] 1`] = `
+"'for-in' loop head declarations can not have an initializer (1:13)
+> 1 | {for (using a = 1 in b);}
+    |             ^^^^^^^^
+Cause: [1:12-1:20]: 'for-in' loop head declarations can not have an initializer"
+`;
+
+exports[`snippet: #2 format[oxc] 1`] = `
+"Expected \`;\` but found \`)\` (1:23)
+> 1 | {for (using a = 1 in b);}
+    |                       ^"
+`;
+
+exports[`snippet: #2 format[oxc-ts] 1`] = `
+"Expected \`;\` but found \`)\` (1:23)
+> 1 | {for (using a = 1 in b);}
+    |                       ^"
+`;
+
+exports[`snippet: #2 format[typescript] 1`] = `
+"The variable declaration of a 'for...in' statement cannot have an initializer. (1:13)
+> 1 | {for (using a = 1 in b);}
+    |             ^^^^^
+Cause: The variable declaration of a 'for...in' statement cannot have an initializer."
+`;
diff --git a/tests/format/js/_errors_/for-in-invalid-initializer/format.test.js b/tests/format/js/_errors_/for-in-invalid-initializer/format.test.js
new file mode 100644
index 000000000..7c4e3c572
--- /dev/null
+++ b/tests/format/js/_errors_/for-in-invalid-initializer/format.test.js
@@ -0,0 +1,25 @@
+runFormatTest(
+  {
+    importMeta: import.meta,
+    snippets: [
+      "for (let a = 1 in b);",
+      "for (const a = 1 in b);",
+      "{for (using a = 1 in b);}",
+    ],
+  },
+  [
+    // "babel",
+    "acorn",
+    "espree",
+    "meriyah",
+    "typescript",
+    // "babel-ts",
+    "oxc",
+    "oxc-ts",
+    // "yuku",
+    // "yuku-ts",
+    "flow",
+    "hermes",
+    // "__babel_estree",
+  ],
+);