fix: stop resetInputValue writing a stale state snapshot on blur

src/index.tsx

@@ -700,10 +700,7 @@ export class DatePicker extends Component<DatePickerProps, DatePickerState> {
   };
 
   resetInputValue = () => {
-    this.setState({
-      ...this.state,
-      inputValue: null,
-    });
+    this.setState({ inputValue: null });
   };
 
   handleBlur = (event: React.FocusEvent<HTMLElement>) => {

src/test/reset_input_value.test.tsx

@@ -0,0 +1,41 @@
+import { render } from "@testing-library/react";
+import React, { useState, act } from "react";
+
+import DatePicker from "../index";
+
+function Fixture() {
+  const [date, setDate] = useState<Date | null>(null);
+  return (
+    <div>
+      <DatePicker id="start" selected={date} onChange={setDate} />
+      <button id="outside">outside</button>
+    </div>
+  );
+}
+
+const openCalendars = () => document.querySelectorAll(".react-datepicker");
+
+describe("DatePicker resetInputValue", () => {
+  it("stays closed when an outside mousedown and the input blur land in the same task", () => {
+    render(<Fixture />);
+    const input = document.querySelector<HTMLInputElement>("#start")!;
+    const outside = document.querySelector<HTMLButtonElement>("#outside")!;
+
+    act(() => {
+      input.focus();
+      input.dispatchEvent(new FocusEvent("focusin", { bubbles: true }));
+    });
+    expect(openCalendars()).toHaveLength(1);
+
+    // A browser dispatches the outside mousedown and the resulting input blur
+    // in a single task. React has not committed setOpen(false) by the time the
+    // blur handler runs, so resetInputValue must not write back a snapshot of
+    // this.state: that snapshot still says open, and the calendar reopens.
+    act(() => {
+      outside.dispatchEvent(new MouseEvent("mousedown", { bubbles: true }));
+      input.dispatchEvent(new FocusEvent("focusout", { bubbles: true }));
+    });
+
+    expect(openCalendars()).toHaveLength(0);
+  });
+});