From 50ba6e0cce2918e7846f4bb4e02312f0a39fef1b Mon Sep 17 00:00:00 2001
From: Samuel Susla <samuelsusla@meta.com>
Date: Tue, 19 Nov 2024 09:55:16 -0800
Subject: [PATCH] add expect().toBeNull() (#47716)

Summary:

changelog: [internal]

Add toBeNull check to Fantom.

Jest docs: https://jestjs.io/docs/expect#tobenull

Reviewed By: javache

Differential Revision: D66167811
---
 jest/integration/runtime/setup.js | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/jest/integration/runtime/setup.js b/jest/integration/runtime/setup.js
index 217d4662b9317f..e33e65795d3337 100644
--- a/jest/integration/runtime/setup.js
+++ b/jest/integration/runtime/setup.js
@@ -215,6 +215,15 @@ class Expect {
     }
   }
 
+  toBeNull(): void {
+    const pass = this.#received == null;
+    if (!this.#isExpectedResult(pass)) {
+      throw new Error(
+        `Expected ${String(this.#received)}${this.#maybeNotLabel()} to be null`,
+      );
+    }
+  }
+
   toThrow(expected?: string): void {
     if (expected != null && typeof expected !== 'string') {
       throw new Error(