diff --git a/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/es_query_expression.test.tsx b/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/es_query_expression.test.tsx
index 45447d58726f4..3b7d049619d25 100644
--- a/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/es_query_expression.test.tsx
+++ b/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/es_query_expression.test.tsx
@@ -5,10 +5,10 @@
  * 2.0.
  */
 
-import React from 'react';
+import React, { PropsWithChildren } from 'react';
+import { fireEvent, render, waitFor, screen, act } from '@testing-library/react';
+import { I18nProvider } from '@kbn/i18n-react';
 import { of, Subject } from 'rxjs';
-import { mountWithIntl, nextTick } from '@kbn/test-jest-helpers';
-import { act } from 'react-dom/test-utils';
 import { dataPluginMock } from '@kbn/data-plugin/public/mocks';
 import { dataViewPluginMocks } from '@kbn/data-views-plugin/public/mocks';
 import { unifiedSearchPluginMock } from '@kbn/unified-search-plugin/public/mocks';
@@ -106,6 +106,10 @@ const createDataPluginMock = () => {
   return dataMock;
 };
 
+const AppWrapper = React.memo<PropsWithChildren<unknown>>(({ children }) => (
+  <I18nProvider>{children}</I18nProvider>
+));
+
 const dataMock = createDataPluginMock();
 const dataViewMock = dataViewPluginMocks.createStartContract();
 const unifiedSearchMock = unifiedSearchPluginMock.createStartContract();
@@ -151,76 +155,71 @@ describe('EsQueryRuleTypeExpression', () => {
       timeWindowSize: [],
     };
 
-    const wrapper = mountWithIntl(
-      <EsQueryExpression
-        unifiedSearch={unifiedSearchMock}
-        ruleInterval="1m"
-        ruleThrottle="1m"
-        alertNotifyWhen="onThrottleInterval"
-        ruleParams={alertParams}
-        setRuleParams={() => {}}
-        setRuleProperty={() => {}}
-        errors={errors}
-        data={dataMock}
-        dataViews={dataViewMock}
-        defaultActionGroupId=""
-        actionGroups={[]}
-        charts={chartsStartMock}
-        onChangeMetaData={() => {}}
-      />
+    return await act(async () =>
+      render(
+        <EsQueryExpression
+          unifiedSearch={unifiedSearchMock}
+          ruleInterval="1m"
+          ruleThrottle="1m"
+          alertNotifyWhen="onThrottleInterval"
+          ruleParams={alertParams}
+          setRuleParams={() => {}}
+          setRuleProperty={() => {}}
+          errors={errors}
+          data={dataMock}
+          dataViews={dataViewMock}
+          defaultActionGroupId=""
+          actionGroups={[]}
+          charts={chartsStartMock}
+          onChangeMetaData={() => {}}
+        />,
+        {
+          wrapper: AppWrapper,
+        }
+      )
     );
-
-    const update = async () =>
-      await act(async () => {
-        await nextTick();
-        wrapper.update();
-      });
-
-    await update();
-    return wrapper;
   }
 
   test('should render EsQueryRuleTypeExpression with expected components', async () => {
-    const wrapper = await setup(defaultEsQueryExpressionParams);
-    expect(wrapper.find('[data-test-subj="indexSelectPopover"]').exists()).toBeTruthy();
-    expect(wrapper.find('[data-test-subj="sizeValueExpression"]').exists()).toBeTruthy();
-    expect(wrapper.find('[data-test-subj="queryJsonEditor"]').exists()).toBeTruthy();
-    expect(wrapper.find('[data-test-subj="testQuerySuccess"]').exists()).toBeFalsy();
-    expect(wrapper.find('[data-test-subj="testQueryError"]').exists()).toBeFalsy();
-    expect(wrapper.find('[data-test-subj="thresholdExpression"]').exists()).toBeTruthy();
-    expect(wrapper.find('[data-test-subj="forLastExpression"]').exists()).toBeTruthy();
-
-    const excludeHitsButton = wrapper.find(
-      '[data-test-subj="excludeHitsFromPreviousRunExpression"]'
-    );
-    expect(excludeHitsButton.exists()).toBeTruthy();
-    expect(excludeHitsButton.first().prop('checked')).toBeTruthy();
+    const result = await setup(defaultEsQueryExpressionParams);
+    expect(result.getByTestId('indexSelectPopover')).toBeInTheDocument();
+    expect(result.getByTestId('sizeValueExpression')).toBeInTheDocument();
+    expect(result.getByTestId('queryJsonEditor')).toBeInTheDocument();
+    expect(result.getByTestId('thresholdPopover')).toBeInTheDocument();
+    expect(result.getByTestId('forLastExpression')).toBeInTheDocument();
+    expect(result.queryByTestId('testQuerySuccess')).not.toBeInTheDocument();
+    expect(result.queryByTestId('testQueryError')).not.toBeInTheDocument();
+
+    expect(result.getByTestId('excludeHitsFromPreviousRunExpression')).toBeChecked();
 
-    const testQueryButton = wrapper.find('EuiButton[data-test-subj="testQuery"]');
-    expect(testQueryButton.exists()).toBeTruthy();
-    expect(testQueryButton.prop('disabled')).toBe(false);
+    expect(result.getByTestId('testQuery')).not.toBeDisabled();
   });
 
   test('should render Test Query button disabled if alert params are invalid', async () => {
-    const wrapper = await setup({
+    const result = await setup({
       ...defaultEsQueryExpressionParams,
       timeField: null,
     } as unknown as EsQueryRuleParams<SearchType.esQuery>);
-    const testQueryButton = wrapper.find('EuiButton[data-test-subj="testQuery"]');
-    expect(testQueryButton.exists()).toBeTruthy();
-    expect(testQueryButton.prop('disabled')).toBe(true);
+
+    expect(result.getByTestId('testQuery')).toBeDisabled();
   });
 
   test('should show excludeHitsFromPreviousRun unchecked by default', async () => {
-    const wrapper = await setup({
+    const result = await setup({
       ...defaultEsQueryExpressionParams,
       excludeHitsFromPreviousRun: undefined,
     } as unknown as EsQueryRuleParams<SearchType.esQuery>);
-    const excludeMatchesCheckBox = wrapper.find(
-      'EuiCheckbox[data-test-subj="excludeHitsFromPreviousRunExpression"]'
-    );
-    expect(excludeMatchesCheckBox.exists()).toBeTruthy();
-    expect(excludeMatchesCheckBox.prop('checked')).toBe(false);
+
+    expect(result.getByTestId('excludeHitsFromPreviousRunExpression')).not.toBeChecked();
+  });
+
+  test('should render EsQueryRuleTypeExpression with chosen size field', async () => {
+    const result = await setup({
+      ...defaultEsQueryExpressionParams,
+      size: 0,
+    } as unknown as EsQueryRuleParams<SearchType.esQuery>);
+
+    expect(result.getByTestId('sizeValueExpression')).toHaveTextContent('Size 0');
   });
 
   test('should show success message if ungrouped Test Query is successful', async () => {
@@ -232,19 +231,14 @@ describe('EsQueryRuleTypeExpression', () => {
       },
     });
     dataMock.search.search.mockImplementation(() => searchResponseMock$);
-    const wrapper = await setup(defaultEsQueryExpressionParams);
-    const testQueryButton = wrapper.find('button[data-test-subj="testQuery"]');
-    testQueryButton.simulate('click');
-    expect(dataMock.search.search).toHaveBeenCalled();
-    await act(async () => {
-      await nextTick();
-      wrapper.update();
-    });
-    expect(wrapper.find('[data-test-subj="testQuerySuccess"]').exists()).toBeTruthy();
-    expect(wrapper.find('[data-test-subj="testQueryError"]').exists()).toBeFalsy();
-    expect(wrapper.find('EuiText[data-test-subj="testQuerySuccess"]').text()).toEqual(
-      `Query matched 1234 documents in the last 15s.`
-    );
+    await setup(defaultEsQueryExpressionParams);
+
+    fireEvent.click(screen.getByTestId('testQuery'));
+    await waitFor(() => expect(dataMock.search.search).toBeCalled());
+
+    expect(screen.getByTestId('testQuerySuccess')).toBeInTheDocument();
+    expect(screen.getByText('Query matched 1234 documents in the last 15s.')).toBeInTheDocument();
+    expect(screen.queryByTestId('testQueryError')).not.toBeInTheDocument();
   });
 
   test('should show success message if grouped Test Query is successful', async () => {
@@ -284,23 +278,18 @@ describe('EsQueryRuleTypeExpression', () => {
       },
     });
     dataMock.search.search.mockImplementation(() => searchResponseMock$);
-    const wrapper = await setup({
+    await setup({
       ...defaultEsQueryExpressionParams,
       termField: 'the-term',
       termSize: 10,
     });
-    const testQueryButton = wrapper.find('button[data-test-subj="testQuery"]');
-    testQueryButton.simulate('click');
-    expect(dataMock.search.search).toHaveBeenCalled();
-    await act(async () => {
-      await nextTick();
-      wrapper.update();
-    });
-    expect(wrapper.find('[data-test-subj="testQuerySuccess"]').exists()).toBeTruthy();
-    expect(wrapper.find('[data-test-subj="testQueryError"]').exists()).toBeFalsy();
-    expect(wrapper.find('EuiText[data-test-subj="testQuerySuccess"]').text()).toEqual(
-      `Grouped query matched 5 groups in the last 15s.`
-    );
+
+    fireEvent.click(screen.getByTestId('testQuery'));
+    await waitFor(() => expect(dataMock.search.search).toBeCalled());
+
+    expect(screen.getByTestId('testQuerySuccess')).toBeInTheDocument();
+    expect(screen.getByText('Grouped query matched 5 groups in the last 15s.')).toBeInTheDocument();
+    expect(screen.queryByTestId('testQueryError')).not.toBeInTheDocument();
   });
 
   test('should show success message if Test Query is successful (with partial result)', async () => {
@@ -319,41 +308,31 @@ describe('EsQueryRuleTypeExpression', () => {
     };
     const searchResponseMock$ = new Subject();
     dataMock.search.search.mockImplementation(() => searchResponseMock$);
-    const wrapper = await setup(defaultEsQueryExpressionParams);
-    const testQueryButton = wrapper.find('button[data-test-subj="testQuery"]');
+    await setup(defaultEsQueryExpressionParams);
 
-    testQueryButton.simulate('click');
-    expect(dataMock.search.search).toHaveBeenCalled();
-    await act(async () => {
+    fireEvent.click(screen.getByTestId('testQuery'));
+    await waitFor(() => expect(dataMock.search.search).toBeCalled());
+    await waitFor(() => {
       searchResponseMock$.next(partial);
       searchResponseMock$.next(complete);
       searchResponseMock$.complete();
-      await nextTick();
-      wrapper.update();
     });
 
-    expect(wrapper.find('[data-test-subj="testQuerySuccess"]').exists()).toBeTruthy();
-    expect(wrapper.find('[data-test-subj="testQueryError"]').exists()).toBeFalsy();
-    expect(wrapper.find('EuiText[data-test-subj="testQuerySuccess"]').text()).toEqual(
-      `Query matched 1234 documents in the last 15s.`
-    );
+    expect(screen.getByTestId('testQuerySuccess')).toBeInTheDocument();
+    expect(screen.getByText('Query matched 1234 documents in the last 15s.')).toBeInTheDocument();
+    expect(screen.queryByTestId('testQueryError')).not.toBeInTheDocument();
   });
 
   test('should show error message if Test Query is throws error', async () => {
     dataMock.search.search.mockImplementation(() => {
       throw new Error('What is this query');
     });
-    const wrapper = await setup(defaultEsQueryExpressionParams);
-    const testQueryButton = wrapper.find('button[data-test-subj="testQuery"]');
-
-    testQueryButton.simulate('click');
-    expect(dataMock.search.search).toHaveBeenCalled();
-    await act(async () => {
-      await nextTick();
-      wrapper.update();
-    });
+    await setup(defaultEsQueryExpressionParams);
+
+    fireEvent.click(screen.getByTestId('testQuery'));
+    await waitFor(() => expect(dataMock.search.search).toBeCalled());
 
-    expect(wrapper.find('[data-test-subj="testQuerySuccess"]').exists()).toBeFalsy();
-    expect(wrapper.find('[data-test-subj="testQueryError"]').exists()).toBeTruthy();
+    expect(screen.queryByTestId('testQuerySuccess')).not.toBeInTheDocument();
+    expect(screen.getByTestId('testQueryError')).toBeInTheDocument();
   });
 });
diff --git a/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/es_query_expression.tsx b/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/es_query_expression.tsx
index e00b7b6c1156d..11298be80956b 100644
--- a/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/es_query_expression.tsx
+++ b/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/es_query_expression.tsx
@@ -68,7 +68,7 @@ export const EsQueryExpression: React.FC<
       timeWindowUnit: timeWindowUnit ?? DEFAULT_VALUES.TIME_WINDOW_UNIT,
       threshold: threshold ?? DEFAULT_VALUES.THRESHOLD,
       thresholdComparator: thresholdComparator ?? DEFAULT_VALUES.THRESHOLD_COMPARATOR,
-      size: size ? size : isServerless ? SERVERLESS_DEFAULT_VALUES.SIZE : DEFAULT_VALUES.SIZE,
+      size: size ?? (isServerless ? SERVERLESS_DEFAULT_VALUES.SIZE : DEFAULT_VALUES.SIZE),
       esQuery: esQuery ?? DEFAULT_VALUES.QUERY,
       aggType: aggType ?? DEFAULT_VALUES.AGGREGATION_TYPE,
       groupBy: groupBy ?? DEFAULT_VALUES.GROUP_BY,
@@ -198,6 +198,7 @@ export const EsQueryExpression: React.FC<
     <Fragment>
       <EuiFormRow
         fullWidth
+        data-test-subj="indexSelectPopover"
         label={
           <FormattedMessage
             id="xpack.stackAlerts.esQuery.ui.selectIndexPrompt"
@@ -207,7 +208,6 @@ export const EsQueryExpression: React.FC<
       >
         <IndexSelectPopover
           index={index}
-          data-test-subj="indexSelectPopover"
           esFields={esFields}
           timeField={timeField}
           errors={errors}
diff --git a/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/search_source_expression.test.tsx b/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/search_source_expression.test.tsx
index 79a5083418483..908b92500b4da 100644
--- a/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/search_source_expression.test.tsx
+++ b/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/search_source_expression.test.tsx
@@ -5,23 +5,21 @@
  * 2.0.
  */
 
-import { mountWithIntl, nextTick } from '@kbn/test-jest-helpers';
-import React from 'react';
+import React, { PropsWithChildren } from 'react';
+import { fireEvent, render, waitFor, screen, act } from '@testing-library/react';
+import { I18nProvider } from '@kbn/i18n-react';
 import { dataPluginMock } from '@kbn/data-plugin/public/mocks';
 import { dataViewPluginMocks } from '@kbn/data-views-plugin/public/mocks';
 import { unifiedSearchPluginMock } from '@kbn/unified-search-plugin/public/mocks';
 import { EsQueryRuleParams, SearchType } from '../types';
 import { SearchSourceExpression } from './search_source_expression';
 import { chartPluginMock } from '@kbn/charts-plugin/public/mocks';
-import { act } from 'react-dom/test-utils';
 import { Subject } from 'rxjs';
 import { ISearchSource } from '@kbn/data-plugin/common';
 import { IUiSettingsClient } from '@kbn/core/public';
-import { findTestSubject } from '@elastic/eui/lib/test';
-import { copyToClipboard, EuiLoadingSpinner } from '@elastic/eui';
+import { copyToClipboard } from '@elastic/eui';
 import { KibanaContextProvider } from '@kbn/kibana-react-plugin/public';
 import { indexPatternEditorPluginMock as dataViewEditorPluginMock } from '@kbn/data-view-editor-plugin/public/mocks';
-import { ReactWrapper } from 'enzyme';
 import { DataPlugin } from '@kbn/data-plugin/public';
 
 jest.mock('@elastic/eui', () => {
@@ -147,6 +145,11 @@ describe('SearchSourceAlertTypeExpression', () => {
   let dataMock: jest.Mocked<ReturnType<DataPlugin['start']>>;
   let searchSourceMock: ISearchSource;
   let mockSearchResult: Subject<unknown>;
+
+  const AppWrapper = React.memo<PropsWithChildren<unknown>>(({ children }) => (
+    <I18nProvider>{children}</I18nProvider>
+  ));
+
   beforeEach(() => {
     mockSearchResult = new Subject();
     searchSourceMock = {
@@ -250,7 +253,7 @@ describe('SearchSourceAlertTypeExpression', () => {
     };
     const dataViewEditorMock = dataViewEditorPluginMock.createStartContract();
 
-    return mountWithIntl(
+    return render(
       <KibanaContextProvider
         services={{
           dataViews: dataViewPluginMock,
@@ -277,108 +280,85 @@ describe('SearchSourceAlertTypeExpression', () => {
           metadata={{ adHocDataViewList: [] }}
           onChangeMetaData={jest.fn()}
         />
-      </KibanaContextProvider>
+      </KibanaContextProvider>,
+      {
+        wrapper: AppWrapper,
+      }
     );
   };
   test('should render correctly', async () => {
-    let wrapper = setup(defaultSearchSourceExpressionParams);
+    const result = setup(defaultSearchSourceExpressionParams);
 
-    expect(wrapper.find(EuiLoadingSpinner).exists()).toBeTruthy();
+    await waitFor(() =>
+      expect(result.getByTestId('searchSourceLoadingSpinner')).toBeInTheDocument()
+    );
 
-    await act(async () => {
-      await nextTick();
-    });
-    wrapper = await wrapper.update();
-    expect(findTestSubject(wrapper, 'thresholdExpression')).toBeTruthy();
+    expect(result.getByTestId('thresholdPopover')).toBeInTheDocument();
+    expect(result.getByTestId('excludeHitsFromPreviousRunExpression')).toBeChecked();
+  });
 
-    const excludeHitsCheckbox = findTestSubject(wrapper, 'excludeHitsFromPreviousRunExpression');
-    expect(excludeHitsCheckbox).toBeTruthy();
-    expect(excludeHitsCheckbox.prop('checked')).toBeTruthy();
+  test('should render chosen size field', async () => {
+    const result = await act(async () =>
+      setup({
+        ...defaultSearchSourceExpressionParams,
+        size: 0,
+      })
+    );
+
+    expect(result.getByTestId('sizeValueExpression')).toHaveTextContent('Size 0');
   });
 
   test('should disable Test Query button if data view is not selected yet', async () => {
-    let wrapper = setup({ ...defaultSearchSourceExpressionParams, searchConfiguration: undefined });
-    await act(async () => {
-      await nextTick();
-    });
-    wrapper = await wrapper.update();
+    const result = await act(async () =>
+      setup({
+        ...defaultSearchSourceExpressionParams,
+        searchConfiguration: undefined,
+      })
+    );
 
-    const testButton = findTestSubject(wrapper, 'testQuery');
-    expect(testButton.prop('disabled')).toBeTruthy();
+    expect(result.getByTestId('testQuery')).toBeDisabled();
   });
 
   test('should show success message if ungrouped Test Query is successful', async () => {
-    let wrapper = setup(defaultSearchSourceExpressionParams);
-    await act(async () => {
-      await nextTick();
-    });
-    wrapper = await wrapper.update();
-    await act(async () => {
-      const testButton = findTestSubject(wrapper, 'testQuery');
-      expect(testButton.prop('disabled')).toBeFalsy();
-      testButton.simulate('click');
-      wrapper.update();
-    });
-    wrapper = await wrapper.update();
+    await act(async () => setup(defaultSearchSourceExpressionParams));
 
-    await act(async () => {
+    fireEvent.click(screen.getByTestId('testQuery'));
+    await waitFor(() => {
       mockSearchResult.next(testResultPartial);
       mockSearchResult.next(testResultComplete);
       mockSearchResult.complete();
-      await nextTick();
-      wrapper.update();
     });
 
-    expect(wrapper.find('[data-test-subj="testQuerySuccess"]').exists()).toBeTruthy();
-    expect(wrapper.find('[data-test-subj="testQueryError"]').exists()).toBeFalsy();
-    expect(wrapper.find('EuiText[data-test-subj="testQuerySuccess"]').text()).toEqual(
-      `Query matched 1234 documents in the last 15s.`
-    );
+    expect(screen.getByTestId('testQuerySuccess')).toBeInTheDocument();
+    expect(screen.getByText('Query matched 1234 documents in the last 15s.')).toBeInTheDocument();
+    expect(screen.queryByTestId('testQueryError')).not.toBeInTheDocument();
   });
 
   test('should show success message if grouped Test Query is successful', async () => {
-    let wrapper = setup({
-      ...defaultSearchSourceExpressionParams,
-      termField: 'the-term',
-      termSize: 10,
-    });
-    await act(async () => {
-      await nextTick();
-    });
-    wrapper = await wrapper.update();
-    await act(async () => {
-      const testButton = findTestSubject(wrapper, 'testQuery');
-      expect(testButton.prop('disabled')).toBeFalsy();
-      testButton.simulate('click');
-      wrapper.update();
-    });
-    wrapper = await wrapper.update();
+    await act(async () =>
+      setup({
+        ...defaultSearchSourceExpressionParams,
+        termField: 'the-term',
+        termSize: 10,
+      })
+    );
 
-    await act(async () => {
+    fireEvent.click(screen.getByTestId('testQuery'));
+    await waitFor(() => {
       mockSearchResult.next(testResultPartial);
       mockSearchResult.next(testResultGroupedComplete);
       mockSearchResult.complete();
-      await nextTick();
-      wrapper.update();
     });
 
-    expect(wrapper.find('[data-test-subj="testQuerySuccess"]').exists()).toBeTruthy();
-    expect(wrapper.find('[data-test-subj="testQueryError"]').exists()).toBeFalsy();
-    expect(wrapper.find('EuiText[data-test-subj="testQuerySuccess"]').text()).toEqual(
-      `Grouped query matched 5 groups in the last 15s.`
-    );
+    expect(screen.getByTestId('testQuerySuccess')).toBeInTheDocument();
+    expect(screen.getByText('Grouped query matched 5 groups in the last 15s.')).toBeInTheDocument();
+    expect(screen.queryByTestId('testQueryError')).not.toBeInTheDocument();
   });
 
   it('should call copyToClipboard with the serialized query when the copy query button is clicked', async () => {
-    let wrapper = null as unknown as ReactWrapper;
-    await act(async () => {
-      wrapper = setup(defaultSearchSourceExpressionParams);
-    });
-    wrapper.update();
-    await act(async () => {
-      findTestSubject(wrapper, 'copyQuery').simulate('click');
-    });
-    wrapper.update();
+    await act(async () => setup(defaultSearchSourceExpressionParams));
+
+    fireEvent.click(screen.getByTestId('copyQuery'));
     expect(copyToClipboard).toHaveBeenCalledWith(`{
   \"fields\": [
     {
@@ -450,16 +430,13 @@ describe('SearchSourceAlertTypeExpression', () => {
     (dataMock.search.searchSource.create as jest.Mock).mockImplementationOnce(() =>
       Promise.reject(new Error('Cant find searchSource'))
     );
-    let wrapper = setup(defaultSearchSourceExpressionParams);
-
-    expect(wrapper.find(EuiLoadingSpinner).exists()).toBeTruthy();
-    expect(wrapper.text().includes('Cant find searchSource')).toBeFalsy();
+    const result = setup(defaultSearchSourceExpressionParams);
 
-    await act(async () => {
-      await nextTick();
+    await waitFor(() => {
+      expect(screen.queryByText('Cant find searchSource')).not.toBeInTheDocument();
+      expect(result.getByTestId('searchSourceLoadingSpinner')).toBeInTheDocument();
     });
-    wrapper = await wrapper.update();
 
-    expect(wrapper.text().includes('Cant find searchSource')).toBeTruthy();
+    expect(screen.getByText('Cant find searchSource')).toBeInTheDocument();
   });
 });
diff --git a/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/search_source_expression.tsx b/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/search_source_expression.tsx
index 57411c7ed3b69..c2471250c5102 100644
--- a/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/search_source_expression.tsx
+++ b/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/search_source_expression.tsx
@@ -85,7 +85,7 @@ export const SearchSourceExpression = ({
           timeWindowUnit: timeWindowUnit ?? DEFAULT_VALUES.TIME_WINDOW_UNIT,
           threshold: threshold ?? DEFAULT_VALUES.THRESHOLD,
           thresholdComparator: thresholdComparator ?? DEFAULT_VALUES.THRESHOLD_COMPARATOR,
-          size: size ? size : isServerless ? SERVERLESS_DEFAULT_VALUES.SIZE : DEFAULT_VALUES.SIZE,
+          size: size ?? (isServerless ? SERVERLESS_DEFAULT_VALUES.SIZE : DEFAULT_VALUES.SIZE),
           aggType: aggType ?? DEFAULT_VALUES.AGGREGATION_TYPE,
           aggField,
           groupBy: groupBy ?? DEFAULT_VALUES.GROUP_BY,
@@ -123,7 +123,11 @@ export const SearchSourceExpression = ({
   }
 
   if (!searchSource) {
-    return <EuiEmptyPrompt title={<EuiLoadingSpinner size="xl" />} />;
+    return (
+      <EuiEmptyPrompt
+        title={<EuiLoadingSpinner data-test-subj="searchSourceLoadingSpinner" size="xl" />}
+      />
+    );
   }
 
   return (
diff --git a/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/search_source_expression_form.tsx b/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/search_source_expression_form.tsx
index 90b22d56e6dc5..ced9beaa3a9cd 100644
--- a/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/search_source_expression_form.tsx
+++ b/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/expression/search_source_expression_form.tsx
@@ -115,11 +115,8 @@ export const SearchSourceExpressionForm = (props: SearchSourceExpressionFormProp
       groupBy: ruleParams.groupBy ?? DEFAULT_VALUES.GROUP_BY,
       termSize: ruleParams.termSize ?? DEFAULT_VALUES.TERM_SIZE,
       termField: ruleParams.termField,
-      size: ruleParams.size
-        ? ruleParams.size
-        : isServerless
-        ? SERVERLESS_DEFAULT_VALUES.SIZE
-        : DEFAULT_VALUES.SIZE,
+      size:
+        ruleParams.size ?? (isServerless ? SERVERLESS_DEFAULT_VALUES.SIZE : DEFAULT_VALUES.SIZE),
       excludeHitsFromPreviousRun:
         ruleParams.excludeHitsFromPreviousRun ?? DEFAULT_VALUES.EXCLUDE_PREVIOUS_HITS,
       sourceFields: ruleParams.sourceFields,
diff --git a/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/rule_common_expressions/rule_common_expressions.tsx b/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/rule_common_expressions/rule_common_expressions.tsx
index c356104ed831f..a2fc48456d52e 100644
--- a/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/rule_common_expressions/rule_common_expressions.tsx
+++ b/x-pack/platform/plugins/shared/stack_alerts/public/rule_types/es_query/rule_common_expressions/rule_common_expressions.tsx
@@ -154,6 +154,7 @@ export const RuleCommonExpressions: React.FC<RuleCommonExpressionsProps> = ({
       <EuiSpacer size="s" />
       <EuiFormRow
         fullWidth
+        data-test-subj="sizeValueExpression"
         label={[
           <FormattedMessage
             id="xpack.stackAlerts.esQuery.ui.selectSizePrompt"
@@ -174,7 +175,6 @@ export const RuleCommonExpressions: React.FC<RuleCommonExpressionsProps> = ({
           description={i18n.translate('xpack.stackAlerts.esQuery.ui.sizeExpression', {
             defaultMessage: 'Size',
           })}
-          data-test-subj="sizeValueExpression"
           value={size}
           errors={errors.size}
           display="fullWidth"