[Cases] Improve useStatefulObservable, remove unnecessary QueryClientProvider

Author: umbopepato

x-pack/plugins/cases/public/common/mock/test_providers.tsx

@@ -19,7 +19,7 @@ import type { ScopedFilesClient } from '@kbn/files-plugin/public';
 import { euiDarkVars } from '@kbn/ui-theme';
 import { I18nProvider } from '@kbn/i18n-react';
 import { createMockFilesClient } from '@kbn/shared-ux-file-mocks';
-import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
+import { QueryClient } from '@tanstack/react-query';
 
 import { KibanaContextProvider } from '@kbn/kibana-react-plugin/public';
 import { FilesContext } from '@kbn/shared-ux-file-context';
@@ -108,10 +108,9 @@ const TestProvidersComponent: React.FC<TestProviderProps> = ({
                 permissions,
                 getFilesClient,
               }}
+              queryClient={queryClient}
             >
-              <QueryClientProvider client={queryClient}>
-                <FilesContext client={createMockFilesClient()}>{children}</FilesContext>
-              </QueryClientProvider>
+              <FilesContext client={createMockFilesClient()}>{children}</FilesContext>
             </CasesProvider>
           </MemoryRouter>
         </ThemeProvider>

x-pack/plugins/cases/public/components/cases_context/use_application.tsx

@@ -13,12 +13,19 @@ interface UseApplicationReturn {
   appTitle: string | undefined;
 }
 
+const isBehaviorSubjectObservable = <T,>(
+  observable: Observable<T>
+): observable is BehaviorSubject<T> => 'value' in observable;
+
 /**
  * Checks if the observable is stateful and, in case, sets up `useObservable` with an initial value
  */
 const useStatefulObservable = <T,>(observable: Observable<T>) => {
-  const defaultValue = 'value' in observable ? (observable as BehaviorSubject<T>).value : undefined;
-  return useObservable(observable, defaultValue);
+  let initialValue: T | undefined;
+  if (isBehaviorSubjectObservable(observable)) {
+    initialValue = observable.value;
+  }
+  return useObservable(observable, initialValue);
 };
 
 export const useApplication = (): UseApplicationReturn => {

x-pack/plugins/cases/public/components/create/description.test.tsx

@@ -17,7 +17,6 @@ import { MAX_DESCRIPTION_LENGTH } from '../../../common/constants';
 import { FormTestComponent } from '../../common/test_utils';
 import type { FormSchema } from '@kbn/index-management-plugin/public/shared_imports';
 
-// FLAKY: https://github.com/elastic/kibana/issues/175204
 describe('Description', () => {
   let appMockRender: AppMockRenderer;
   const onSubmit = jest.fn();