From b0ffc1208d4d115df5a8192fd203e8e9c2b64e01 Mon Sep 17 00:00:00 2001
From: fisker Cheung <lionkay@gmail.com>
Date: Thu, 15 Jan 2026 03:35:07 +0800
Subject: [PATCH] Add test for comments in `hookTypeAnnotation` (#18631)

---
 tests/config/run-format-test.js               |  3 +
 .../hook/__snapshots__/format.test.js.snap    | 62 +++++++++++++++++++
 .../format/flow/hook/comments-before-arrow.js | 25 ++++++++
 3 files changed, 90 insertions(+)
 create mode 100644 tests/format/flow/hook/comments-before-arrow.js

diff --git a/tests/config/run-format-test.js b/tests/config/run-format-test.js
index 8f1eebe9f..d4faab81f 100644
--- a/tests/config/run-format-test.js
+++ b/tests/config/run-format-test.js
@@ -108,6 +108,9 @@ const hermesDisabledTests = new Set([
     // Not supported
     "flow/comments",
     "flow-repo/union_new",
+
+    // Different result
+    "flow/hook/comments-before-arrow.js",
   ].map((file) => path.join(__dirname, "../format", file)),
 ]);
 const flowDisabledTests = new Set(
diff --git a/tests/format/flow/hook/__snapshots__/format.test.js.snap b/tests/format/flow/hook/__snapshots__/format.test.js.snap
index be2fc7195..0f6c584a0 100644
--- a/tests/format/flow/hook/__snapshots__/format.test.js.snap
+++ b/tests/format/flow/hook/__snapshots__/format.test.js.snap
@@ -1,5 +1,67 @@
 // Jest Snapshot v1, https://jestjs.io/docs/snapshot-testing
 
+exports[`comments-before-arrow.js format 1`] = `
+====================================options=====================================
+parsers: ["flow"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+/*
+The following should format like \`ArrowFunctionExpression\`,
+but currently the AST shape are different, and it allows line break before \`=>\`
+
+This is valid
+
+\`\`\`
+type A1 = hook  () /*
+1 *\\/ => void
+\`\`\`
+
+while this is invalid
+
+\`\`\`
+a = () /*
+1 *\\/ => void
+\`\`\`
+*/
+type A1 = hook /* 11 */ () => void
+type A2 = hook () /* 12 */ => void
+type A3 = hook ()  => /* 13 */ void
+
+a = /* 21 */ () => {}
+a = () /* 22 */ => {}
+a = ()  => /* 23 */ {}
+
+=====================================output=====================================
+/*
+The following should format like \`ArrowFunctionExpression\`,
+but currently the AST shape are different, and it allows line break before \`=>\`
+
+This is valid
+
+\`\`\`
+type A1 = hook  () /*
+1 *\\/ => void
+\`\`\`
+
+while this is invalid
+
+\`\`\`
+a = () /*
+1 *\\/ => void
+\`\`\`
+*/
+type A1 = hook () => /* 11 */ void;
+type A2 = hook () => /* 12 */ void;
+type A3 = hook () => /* 13 */ void;
+
+a = /* 21 */ () => {};
+a = () /* 22 */ => {};
+a = () => /* 23 */ {};
+
+================================================================================
+`;
+
 exports[`dangling-comments.js format 1`] = `
 ====================================options=====================================
 parsers: ["flow"]
diff --git a/tests/format/flow/hook/comments-before-arrow.js b/tests/format/flow/hook/comments-before-arrow.js
new file mode 100644
index 000000000..05559faf9
--- /dev/null
+++ b/tests/format/flow/hook/comments-before-arrow.js
@@ -0,0 +1,25 @@
+/*
+The following should format like `ArrowFunctionExpression`,
+but currently the AST shape are different, and it allows line break before `=>`
+
+This is valid
+
+```
+type A1 = hook  () /*
+1 *\/ => void
+```
+
+while this is invalid
+
+```
+a = () /*
+1 *\/ => void
+```
+*/
+type A1 = hook /* 11 */ () => void
+type A2 = hook () /* 12 */ => void
+type A3 = hook ()  => /* 13 */ void
+
+a = /* 21 */ () => {}
+a = () /* 22 */ => {}
+a = ()  => /* 23 */ {}