1 files changed, 24 insertions, 0 deletions
diff --git a/test/js/web/html/FormData.test.ts b/test/js/web/html/FormData.test.ts
index af2871b10..abb298c1a 100644
--- a/test/js/web/html/FormData.test.ts
+++ b/test/js/web/html/FormData.test.ts
@@ -338,6 +338,30 @@ describe("FormData", () => {
     expect(Bun.inspect(formData).length > 0).toBe(true);
   });
 
+  describe("non-standard extensions", () => {
+    it("should support .length", () => {
+      const formData = new FormData();
+      formData.append("foo", "bar");
+      formData.append("foo", new Blob(["bar"]));
+      formData.append("bar", "baz");
+      // @ts-ignore
+      expect(formData.length).toBe(3);
+      formData.delete("foo");
+      // @ts-ignore
+      expect(formData.length).toBe(1);
+      formData.append("foo", "bar");
+      // @ts-ignore
+      expect(formData.length).toBe(2);
+      formData.delete("foo");
+      formData.delete("foo");
+      // @ts-ignore
+      expect(formData.length).toBe(1);
+      formData.delete("bar");
+      // @ts-ignore
+      expect(formData.length).toBe(0);
+    });
+  });
+
   describe("URLEncoded", () => {
     test("should parse URL encoded", async () => {
       const response = new Response("foo=bar&baz=qux", {