[ResponseOps][MaintenanceWindows] Fix startDate not forwarded to custom recurrence component (#223949)

## Summary

- Forwards `startDate` correctly to the `CustomRecurringSchedule`
component. The missing prop caused the monthly custom frequency
sub-options to not show up.
- Fixes the `CustomRecurringSchedule` component type to correctly
reflect the required prop.
- Removes the `custom-recurring-form` data test subject from the
`<CustomRecurringSchedule>` JSX tag. The test subject wasn't forwarded
to any DOM element, but the only test with an assertion using that test
subject was passing because it was checking its absence
(`not.toBeInTheDocument()`).

## Verification steps

1. Open the Maintenance Window creation page
2. Toggle "Repeat" on
3. In the recurrence form, check that all the custom frequencies work,
showing the correct sub-options

src/platform/packages/shared/response-ops/recurring-schedule-form/components/custom_recurring_schedule.test.tsx

@@ -37,6 +37,8 @@ const TestWrapper = ({ children, iv = initialValue }: PropsWithChildren<{ iv?: F
   return <Form form={form}>{children}</Form>;
 };
 
+const startDate = new Date().toISOString();
+
 describe('CustomRecurringSchedule', () => {
   beforeEach(() => {
     jest.clearAllMocks();
@@ -45,7 +47,7 @@ describe('CustomRecurringSchedule', () => {
   it('renders all form fields', async () => {
     render(
       <TestWrapper>
-        <CustomRecurringSchedule />
+        <CustomRecurringSchedule startDate={startDate} />
       </TestWrapper>
     );
 
@@ -58,7 +60,7 @@ describe('CustomRecurringSchedule', () => {
   it('renders byweekday field if custom frequency = weekly', async () => {
     render(
       <TestWrapper>
-        <CustomRecurringSchedule />
+        <CustomRecurringSchedule startDate={startDate} />
       </TestWrapper>
     );
 
@@ -83,7 +85,7 @@ describe('CustomRecurringSchedule', () => {
     };
     render(
       <TestWrapper iv={iv}>
-        <CustomRecurringSchedule />
+        <CustomRecurringSchedule startDate={startDate} />
       </TestWrapper>
     );
 
@@ -93,7 +95,7 @@ describe('CustomRecurringSchedule', () => {
   it('renders bymonth field if custom frequency = monthly', async () => {
     render(
       <TestWrapper>
-        <CustomRecurringSchedule />
+        <CustomRecurringSchedule startDate={startDate} />
       </TestWrapper>
     );
 
@@ -111,7 +113,7 @@ describe('CustomRecurringSchedule', () => {
   it('should initialize the form when no initialValue provided', () => {
     render(
       <TestWrapper>
-        <CustomRecurringSchedule />
+        <CustomRecurringSchedule startDate={startDate} />
       </TestWrapper>
     );
 
@@ -139,7 +141,7 @@ describe('CustomRecurringSchedule', () => {
     };
     render(
       <TestWrapper iv={iv}>
-        <CustomRecurringSchedule />
+        <CustomRecurringSchedule startDate={startDate} />
       </TestWrapper>
     );
 

src/platform/packages/shared/response-ops/recurring-schedule-form/components/custom_recurring_schedule.tsx

@@ -7,7 +7,7 @@
  * License v3.0 only", or the "Server Side Public License, v 1".
  */
 
-import React, { useMemo } from 'react';
+import React, { memo, useMemo } from 'react';
 import { Frequency } from '@kbn/rrule';
 import moment from 'moment';
 import { css } from '@emotion/react';
@@ -42,11 +42,10 @@ const styles = {
 };
 
 export interface CustomRecurringScheduleProps {
-  startDate?: string;
+  startDate: string;
 }
 
-export const CustomRecurringSchedule: React.FC = React.memo(
-  ({ startDate }: CustomRecurringScheduleProps) => {
+export const CustomRecurringSchedule = memo(({ startDate }: CustomRecurringScheduleProps) => {
   const [{ recurringSchedule }] = useFormData<{ recurringSchedule: RecurringSchedule }>({
     watch: [
       'recurringSchedule.frequency',
@@ -171,7 +170,6 @@ export const CustomRecurringSchedule: React.FC = React.memo(
       ) : null}
     </>
   );
-  }
-);
+});
 
 CustomRecurringSchedule.displayName = 'CustomRecurringSchedule';

src/platform/packages/shared/response-ops/recurring-schedule-form/components/recurring_schedule_form_fields.test.tsx

@@ -18,6 +18,7 @@ import type { RecurringSchedule } from '../types';
 import { Form, useForm } from '@kbn/es-ui-shared-plugin/static/forms/hook_form_lib';
 import { getRecurringScheduleFormSchema } from '../schemas/recurring_schedule_form_schema';
 import { RecurrenceEnd } from '../constants';
+import { Frequency } from '@kbn/rrule';
 
 const baseProps: RecurringScheduleFieldsProps = {
   startDate: '2023-03-24',
@@ -29,7 +30,7 @@ interface FormValue {
 
 const initialValue: FormValue = {
   recurringSchedule: {
-    frequency: 'CUSTOM',
+    frequency: Frequency.WEEKLY,
     ends: RecurrenceEnd.NEVER,
   },
 };
@@ -57,7 +58,7 @@ describe('RecurringScheduleForm', () => {
     );
 
     expect(screen.getByTestId('frequency-field')).toBeInTheDocument();
-    expect(screen.queryByTestId('custom-recurring-form')).not.toBeInTheDocument();
+    expect(screen.queryByTestId('customRecurringScheduleIntervalInput')).not.toBeInTheDocument();
     expect(screen.getByTestId('ends-field')).toBeInTheDocument();
     expect(screen.queryByTestId('until-field')).not.toBeInTheDocument();
     expect(screen.queryByTestId('count-field')).not.toBeInTheDocument();
@@ -88,4 +89,28 @@ describe('RecurringScheduleForm', () => {
     await userEvent.click(btn);
     expect(await screen.findByTestId('count-field')).toBeInTheDocument();
   });
+
+  it('renders custom schedule if frequency = daily', async () => {
+    render(
+      <TestWrapper
+        iv={{ recurringSchedule: { frequency: Frequency.DAILY, ends: RecurrenceEnd.NEVER } }}
+      >
+        <RecurringScheduleFormFields {...baseProps} />
+      </TestWrapper>
+    );
+
+    expect(
+      await screen.findByTestId('customRecurringScheduleByWeekdayButtonGroup')
+    ).toBeInTheDocument();
+  });
+
+  it('renders custom schedule if frequency = custom', async () => {
+    render(
+      <TestWrapper iv={{ recurringSchedule: { frequency: 'CUSTOM', ends: RecurrenceEnd.NEVER } }}>
+        <RecurringScheduleFormFields {...baseProps} />
+      </TestWrapper>
+    );
+
+    expect(await screen.findByTestId('customRecurringScheduleIntervalInput')).toBeInTheDocument();
+  });
 });

src/platform/packages/shared/response-ops/recurring-schedule-form/components/recurring_schedule_form_fields.tsx

@@ -59,7 +59,7 @@ export const toMoment = (value: string): Moment => moment(value);
 export const toString = (value: Moment): string => value.toISOString();
 
 export interface RecurringScheduleFieldsProps {
-  startDate?: string;
+  startDate: string;
   endDate?: string;
   timezone?: string[];
   allowInfiniteRecurrence?: boolean;
@@ -147,7 +147,7 @@ export const RecurringScheduleFormFields = memo(
           />
           {(parsedSchedule?.frequency === Frequency.DAILY ||
             parsedSchedule?.frequency === 'CUSTOM') && (
-            <CustomRecurringSchedule data-test-subj="custom-recurring-form" />
+            <CustomRecurringSchedule startDate={startDate} />
           )}
           <UseField
             path="recurringSchedule.ends"