From 59274dd84fb3a1643687b6e4b007ddaf51b11e39 Mon Sep 17 00:00:00 2001
From: Nicolas DUBIEN <github@dubien.org>
Date: Tue, 8 Dec 2020 09:10:54 +0100
Subject: [PATCH 1/2] Ensure toContain only accepts strings when received is a
 string

Follow-up of #10119
---
 .../__tests__/__snapshots__/matchers.test.js.snap   | 11 +++++++++++
 packages/expect/src/__tests__/matchers.test.js      |  8 ++++++++
 packages/expect/src/matchers.ts                     | 13 +------------
 3 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap b/packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap
index 4ad971a5dbf3..ca39274cdb18 100644
--- a/packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap
+++ b/packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap
@@ -1989,6 +1989,17 @@ Received has type:  string
 Received has value: <r>"undefined"</>
 `;
 
+exports[`.toContain(), .toContainEqual() error cases 5`] = `
+<d>expect(</><r>false</><d>).</>toContain<d>(</><g>false</><d>) // indexOf</>
+
+<b>Matcher error</>: <g>expected</> value must be a string if <r>received</> value is a string
+
+Expected has type:  boolean
+Expected has value: <g>false</>
+Received has type:  string
+Received has value: <r>"false"</>
+`;
+
 exports[`.toContain(), .toContainEqual() error cases for toContainEqual 1`] = `
 <d>expect(</><r>received</><d>).</>toContainEqual<d>(</><g>expected</><d>) // deep equality</>
 
diff --git a/packages/expect/src/__tests__/matchers.test.js b/packages/expect/src/__tests__/matchers.test.js
index 5f07e34123be..5b24688e69d0 100644
--- a/packages/expect/src/__tests__/matchers.test.js
+++ b/packages/expect/src/__tests__/matchers.test.js
@@ -1470,6 +1470,14 @@ describe('.toContain(), .toContainEqual()', () => {
     expect(() =>
       jestExpect('undefined').toContain(undefined),
     ).toThrowErrorMatchingSnapshot();
+    expect(() =>
+      jestExpect('false').toContain(false),
+    ).toThrowErrorMatchingSnapshot();
+    if (isBigIntDefined) {
+      expect(() => jestExpect('1').toContain(BigInt(1))).toThrowError(
+        'toContain',
+      );
+    }
   });
 
   [
diff --git a/packages/expect/src/matchers.ts b/packages/expect/src/matchers.ts
index fc0074199486..99a3c7e9fd42 100644
--- a/packages/expect/src/matchers.ts
+++ b/packages/expect/src/matchers.ts
@@ -480,18 +480,7 @@ const matchers: MatchersObject = {
         'received',
       )} value is a string`;
 
-      if (expected == null) {
-        throw new Error(
-          matcherErrorMessage(
-            matcherHint(matcherName, received, String(expected), options),
-            wrongTypeErrorMessage,
-            printWithType('Expected', expected, printExpected) +
-              '\n' +
-              printWithType('Received', received, printReceived),
-          ),
-        );
-      }
-      if (typeof expected === 'number') {
+      if (typeof expected !== 'string') {
         throw new Error(
           matcherErrorMessage(
             matcherHint(matcherName, received, String(expected), options),

From 61febc5048959bd75ee0e90214f264c53a4a3ca1 Mon Sep 17 00:00:00 2001
From: Simen Bekkhus <sbekkhus91@gmail.com>
Date: Tue, 8 Dec 2020 10:00:06 +0100
Subject: [PATCH 2/2] Update CHANGELOG.md

---
 CHANGELOG.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 575b81f699b2..f7e8e3b07be7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -19,7 +19,7 @@
 
 - `[babel-plugin-jest-hoist]` Add `__dirname` and `__filename` to whitelisted globals ([#10903](https://github.com/facebook/jest/pull/10903))
 - `[expect]` [**BREAKING**] Revise `expect.not.objectContaining()` to be the inverse of `expect.objectContaining()`, as documented. ([#10708](https://github.com/facebook/jest/pull/10708))
-- `[expect]` [**BREAKING**] Make `toContain` more strict with the received type ([#10119](https://github.com/facebook/jest/pull/10119))
+- `[expect]` [**BREAKING**] Make `toContain` more strict with the received type ([#10119](https://github.com/facebook/jest/pull/10119) & [#10929](https://github.com/facebook/jest/pull/10929))
 - `[jest-circus]` Fixed the issue of beforeAll & afterAll hooks getting executed even if it is inside a skipped `describe` block [#10451](https://github.com/facebook/jest/issues/10451)
 - `[jest-circus]` Fix `testLocation` on Windows when using `test.each` ([#10871](https://github.com/facebook/jest/pull/10871))
 - `[jest-console]` `console.dir` now respects the second argument correctly ([#10638](https://github.com/facebook/jest/pull/10638))