From 317c41372e9461564a9e511c72f547f1e2fd7d7a Mon Sep 17 00:00:00 2001
From: Gareth Jones <Jones258@Gmail.com>
Date: Sat, 11 Apr 2020 20:30:10 +1200
Subject: [PATCH] fix(expect): accept functions in `toHaveLength` matcher
 (#9796)

---
 CHANGELOG.md                                               | 2 ++
 .../src/__tests__/__snapshots__/matchers.test.js.snap      | 7 +++++++
 packages/expect/src/__tests__/matchers.test.js             | 1 +
 packages/expect/src/matchers.ts                            | 2 +-
 4 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0d46677941a5..fa2445e8f8b4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,8 @@
 
 ### Fixes
 
+- `[expect]` Restore support for passing functions to `toHaveLength` matcher ([#9796](https://github.com/facebook/jest/pull/9796))
+
 ### Chore & Maintenance
 
 ### Performance
diff --git a/packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap b/packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap
index bc1abc19adf6..e442e66efcaf 100644
--- a/packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap
+++ b/packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap
@@ -3046,6 +3046,13 @@ Expected length: not <g>2</>
 Received array:      <r>[1, 2]</>
 `;
 
+exports[`.toHaveLength {pass: true} expect([Function anonymous]).toHaveLength(0) 1`] = `
+<d>expect(</><r>received</><d>).</>not<d>.</>toHaveLength<d>(</><g>expected</><d>)</>
+
+Expected length:   not <g>0</>
+Received function:     <r>[Function anonymous]</>
+`;
+
 exports[`.toHaveLength error cases 1`] = `
 <d>expect(</><r>received</><d>).</>toHaveLength<d>(</><g>expected</><d>)</>
 
diff --git a/packages/expect/src/__tests__/matchers.test.js b/packages/expect/src/__tests__/matchers.test.js
index 8d1ec4fbea8c..89f25a561ea8 100644
--- a/packages/expect/src/__tests__/matchers.test.js
+++ b/packages/expect/src/__tests__/matchers.test.js
@@ -1694,6 +1694,7 @@ describe('.toHaveLength', () => {
     [['a', 'b'], 2],
     ['abc', 3],
     ['', 0],
+    [() => {}, 0],
   ].forEach(([received, length]) => {
     test(`{pass: true} expect(${stringify(
       received,
diff --git a/packages/expect/src/matchers.ts b/packages/expect/src/matchers.ts
index 26c7725e2de1..cd7274425fb0 100644
--- a/packages/expect/src/matchers.ts
+++ b/packages/expect/src/matchers.ts
@@ -630,7 +630,7 @@ const matchers: MatchersObject = {
 
     if (
       typeof received !== 'string' &&
-      (typeof received !== 'object' || typeof received.length !== 'number')
+      (!received || typeof received.length !== 'number')
     ) {
       throw new Error(
         matcherErrorMessage(