diff --git a/docs/data/api/alert-dialog-portal.json b/docs/data/api/alert-dialog-portal.json
index 544dceaa1a..970162b27f 100644
--- a/docs/data/api/alert-dialog-portal.json
+++ b/docs/data/api/alert-dialog-portal.json
@@ -5,6 +5,8 @@
     "import { AlertDialog } from '@base-ui-components/react/alert-dialog';\nconst AlertDialogPortal = AlertDialog.Portal;"
   ],
   "classes": [],
+  "spread": true,
+  "themeDefaultProps": null,
   "muiName": "AlertDialogPortal",
   "filename": "/packages/react/src/alert-dialog/portal/AlertDialogPortal.tsx",
   "inheritance": null,
diff --git a/docs/data/api/dialog-portal.json b/docs/data/api/dialog-portal.json
index 499e4af478..9f62cb2cec 100644
--- a/docs/data/api/dialog-portal.json
+++ b/docs/data/api/dialog-portal.json
@@ -5,6 +5,8 @@
     "import { Dialog } from '@base-ui-components/react/dialog';\nconst DialogPortal = Dialog.Portal;"
   ],
   "classes": [],
+  "spread": true,
+  "themeDefaultProps": null,
   "muiName": "DialogPortal",
   "filename": "/packages/react/src/dialog/portal/DialogPortal.tsx",
   "inheritance": null,
diff --git a/docs/data/api/menu-portal.json b/docs/data/api/menu-portal.json
index b6e6fb539a..dd46ddafcb 100644
--- a/docs/data/api/menu-portal.json
+++ b/docs/data/api/menu-portal.json
@@ -5,6 +5,8 @@
     "import { Menu } from '@base-ui-components/react/menu';\nconst MenuPortal = Menu.Portal;"
   ],
   "classes": [],
+  "spread": true,
+  "themeDefaultProps": null,
   "muiName": "MenuPortal",
   "filename": "/packages/react/src/menu/portal/MenuPortal.tsx",
   "inheritance": null,
diff --git a/docs/data/api/popover-portal.json b/docs/data/api/popover-portal.json
index f0e9f2cb3f..ab887598fe 100644
--- a/docs/data/api/popover-portal.json
+++ b/docs/data/api/popover-portal.json
@@ -5,6 +5,8 @@
     "import { Popover } from '@base-ui-components/react/popover';\nconst PopoverPortal = Popover.Portal;"
   ],
   "classes": [],
+  "spread": true,
+  "themeDefaultProps": null,
   "muiName": "PopoverPortal",
   "filename": "/packages/react/src/popover/portal/PopoverPortal.tsx",
   "inheritance": null,
diff --git a/docs/data/api/preview-card-portal.json b/docs/data/api/preview-card-portal.json
index 56579d4666..e46f6ae49b 100644
--- a/docs/data/api/preview-card-portal.json
+++ b/docs/data/api/preview-card-portal.json
@@ -5,6 +5,8 @@
     "import { PreviewCard } from '@base-ui-components/react/preview-card';\nconst PreviewCardPortal = PreviewCard.Portal;"
   ],
   "classes": [],
+  "spread": true,
+  "themeDefaultProps": null,
   "muiName": "PreviewCardPortal",
   "filename": "/packages/react/src/preview-card/portal/PreviewCardPortal.tsx",
   "inheritance": null,
diff --git a/docs/data/api/select-portal.json b/docs/data/api/select-portal.json
index 51a8261cd1..11f6ccba6c 100644
--- a/docs/data/api/select-portal.json
+++ b/docs/data/api/select-portal.json
@@ -5,6 +5,8 @@
     "import { Select } from '@base-ui-components/react/select';\nconst SelectPortal = Select.Portal;"
   ],
   "classes": [],
+  "spread": true,
+  "themeDefaultProps": null,
   "muiName": "SelectPortal",
   "filename": "/packages/react/src/select/portal/SelectPortal.tsx",
   "inheritance": null,
diff --git a/docs/data/api/tooltip-portal.json b/docs/data/api/tooltip-portal.json
index ee49c7a672..842bac8746 100644
--- a/docs/data/api/tooltip-portal.json
+++ b/docs/data/api/tooltip-portal.json
@@ -5,6 +5,8 @@
     "import { Tooltip } from '@base-ui-components/react/tooltip';\nconst TooltipPortal = Tooltip.Portal;"
   ],
   "classes": [],
+  "spread": true,
+  "themeDefaultProps": null,
   "muiName": "TooltipPortal",
   "filename": "/packages/react/src/tooltip/portal/TooltipPortal.tsx",
   "inheritance": null,
diff --git a/packages/react/src/alert-dialog/portal/AlertDialogPortal.test.tsx b/packages/react/src/alert-dialog/portal/AlertDialogPortal.test.tsx
index ef2f24da6d..faa243a872 100644
--- a/packages/react/src/alert-dialog/portal/AlertDialogPortal.test.tsx
+++ b/packages/react/src/alert-dialog/portal/AlertDialogPortal.test.tsx
@@ -1,18 +1,20 @@
 import * as React from 'react';
 import { AlertDialog } from '@base-ui-components/react/alert-dialog';
-import { createRenderer, describeConformance } from '#test-utils';
+import { screen } from '@mui/internal-test-utils';
+import { createRenderer } from '#test-utils';
+import { expect } from 'chai';
 
 describe('<AlertDialog.Portal />', () => {
   const { render } = createRenderer();
 
-  describeConformance(<AlertDialog.Portal />, () => ({
-    refInstanceof: null,
-    render(node) {
-      return render(
-        <AlertDialog.Root open animated={false}>
-          {node}
-        </AlertDialog.Root>,
-      );
-    },
-  }));
+  it('renders children', async () => {
+    await render(
+      <AlertDialog.Root open>
+        <AlertDialog.Portal data-testid="portal">
+          <AlertDialog.Popup data-testid="popup" />
+        </AlertDialog.Portal>
+      </AlertDialog.Root>,
+    );
+    expect(screen.getByTestId('popup')).not.to.equal(null);
+  });
 });
diff --git a/packages/react/src/dialog/portal/DialogPortal.test.tsx b/packages/react/src/dialog/portal/DialogPortal.test.tsx
index 12c004e476..cd6aea891a 100644
--- a/packages/react/src/dialog/portal/DialogPortal.test.tsx
+++ b/packages/react/src/dialog/portal/DialogPortal.test.tsx
@@ -1,18 +1,20 @@
 import * as React from 'react';
 import { Dialog } from '@base-ui-components/react/dialog';
-import { createRenderer, describeConformance } from '#test-utils';
+import { screen } from '@mui/internal-test-utils';
+import { createRenderer } from '#test-utils';
+import { expect } from 'chai';
 
 describe('<Dialog.Portal />', () => {
   const { render } = createRenderer();
 
-  describeConformance(<Dialog.Portal />, () => ({
-    refInstanceof: null,
-    render(node) {
-      return render(
-        <Dialog.Root open animated={false}>
-          {node}
-        </Dialog.Root>,
-      );
-    },
-  }));
+  it('renders children', async () => {
+    await render(
+      <Dialog.Root open>
+        <Dialog.Portal data-testid="portal">
+          <Dialog.Popup data-testid="popup" />
+        </Dialog.Portal>
+      </Dialog.Root>,
+    );
+    expect(screen.getByTestId('popup')).not.to.equal(null);
+  });
 });
diff --git a/packages/react/src/menu/portal/MenuPortal.test.tsx b/packages/react/src/menu/portal/MenuPortal.test.tsx
index 48c11e9c18..9b7768bd96 100644
--- a/packages/react/src/menu/portal/MenuPortal.test.tsx
+++ b/packages/react/src/menu/portal/MenuPortal.test.tsx
@@ -1,18 +1,20 @@
 import * as React from 'react';
 import { Menu } from '@base-ui-components/react/menu';
-import { createRenderer, describeConformance } from '#test-utils';
+import { screen } from '@mui/internal-test-utils';
+import { createRenderer } from '#test-utils';
+import { expect } from 'chai';
 
 describe('<Menu.Portal />', () => {
   const { render } = createRenderer();
 
-  describeConformance(<Menu.Portal />, () => ({
-    refInstanceof: null,
-    render(node) {
-      return render(
-        <Menu.Root open animated={false}>
-          {node}
-        </Menu.Root>,
-      );
-    },
-  }));
+  it('renders children', async () => {
+    await render(
+      <Menu.Root open>
+        <Menu.Portal data-testid="portal">
+          <Menu.Positioner data-testid="positioner" />
+        </Menu.Portal>
+      </Menu.Root>,
+    );
+    expect(screen.getByTestId('positioner')).not.to.equal(null);
+  });
 });
diff --git a/packages/react/src/popover/portal/PopoverPortal.test.tsx b/packages/react/src/popover/portal/PopoverPortal.test.tsx
index c14f416cf3..76b062044e 100644
--- a/packages/react/src/popover/portal/PopoverPortal.test.tsx
+++ b/packages/react/src/popover/portal/PopoverPortal.test.tsx
@@ -1,18 +1,20 @@
 import * as React from 'react';
 import { Popover } from '@base-ui-components/react/popover';
-import { createRenderer, describeConformance } from '#test-utils';
+import { screen } from '@mui/internal-test-utils';
+import { createRenderer } from '#test-utils';
+import { expect } from 'chai';
 
 describe('<Popover.Portal />', () => {
   const { render } = createRenderer();
 
-  describeConformance(<Popover.Portal />, () => ({
-    refInstanceof: null,
-    render(node) {
-      return render(
-        <Popover.Root open animated={false}>
-          {node}
-        </Popover.Root>,
-      );
-    },
-  }));
+  it('renders children', async () => {
+    await render(
+      <Popover.Root open>
+        <Popover.Portal data-testid="portal">
+          <Popover.Positioner data-testid="positioner" />
+        </Popover.Portal>
+      </Popover.Root>,
+    );
+    expect(screen.getByTestId('positioner')).not.to.equal(null);
+  });
 });
diff --git a/packages/react/src/preview-card/portal/PreviewCardPortal.test.tsx b/packages/react/src/preview-card/portal/PreviewCardPortal.test.tsx
index ce5fe61da9..6e82326c44 100644
--- a/packages/react/src/preview-card/portal/PreviewCardPortal.test.tsx
+++ b/packages/react/src/preview-card/portal/PreviewCardPortal.test.tsx
@@ -1,18 +1,20 @@
 import * as React from 'react';
 import { PreviewCard } from '@base-ui-components/react/preview-card';
-import { createRenderer, describeConformance } from '#test-utils';
+import { screen } from '@mui/internal-test-utils';
+import { createRenderer } from '#test-utils';
+import { expect } from 'chai';
 
 describe('<PreviewCard.Portal />', () => {
   const { render } = createRenderer();
 
-  describeConformance(<PreviewCard.Portal />, () => ({
-    refInstanceof: null,
-    render(node) {
-      return render(
-        <PreviewCard.Root open animated={false}>
-          {node}
-        </PreviewCard.Root>,
-      );
-    },
-  }));
+  it('renders children', async () => {
+    await render(
+      <PreviewCard.Root open>
+        <PreviewCard.Portal data-testid="portal">
+          <PreviewCard.Positioner data-testid="positioner" />
+        </PreviewCard.Portal>
+      </PreviewCard.Root>,
+    );
+    expect(screen.getByTestId('positioner')).not.to.equal(null);
+  });
 });
diff --git a/packages/react/src/select/portal/SelectPortal.test.tsx b/packages/react/src/select/portal/SelectPortal.test.tsx
index 28daeac24c..72e4e190d8 100644
--- a/packages/react/src/select/portal/SelectPortal.test.tsx
+++ b/packages/react/src/select/portal/SelectPortal.test.tsx
@@ -1,18 +1,20 @@
 import * as React from 'react';
 import { Select } from '@base-ui-components/react/select';
-import { createRenderer, describeConformance } from '#test-utils';
+import { screen } from '@mui/internal-test-utils';
+import { createRenderer } from '#test-utils';
+import { expect } from 'chai';
 
 describe('<Select.Portal />', () => {
   const { render } = createRenderer();
 
-  describeConformance(<Select.Portal />, () => ({
-    refInstanceof: null,
-    render(node) {
-      return render(
-        <Select.Root open animated={false}>
-          {node}
-        </Select.Root>,
-      );
-    },
-  }));
+  it('renders children', async () => {
+    await render(
+      <Select.Root open>
+        <Select.Portal data-testid="portal">
+          <Select.Positioner data-testid="positioner" />
+        </Select.Portal>
+      </Select.Root>,
+    );
+    expect(screen.getByTestId('positioner')).not.to.equal(null);
+  });
 });
diff --git a/packages/react/src/tooltip/portal/TooltipPortal.test.tsx b/packages/react/src/tooltip/portal/TooltipPortal.test.tsx
index 175e7faad2..3be0d7fa25 100644
--- a/packages/react/src/tooltip/portal/TooltipPortal.test.tsx
+++ b/packages/react/src/tooltip/portal/TooltipPortal.test.tsx
@@ -1,18 +1,20 @@
 import * as React from 'react';
 import { Tooltip } from '@base-ui-components/react/tooltip';
-import { createRenderer, describeConformance } from '#test-utils';
+import { screen } from '@mui/internal-test-utils';
+import { createRenderer } from '#test-utils';
+import { expect } from 'chai';
 
 describe('<Tooltip.Portal />', () => {
   const { render } = createRenderer();
 
-  describeConformance(<Tooltip.Portal />, () => ({
-    refInstanceof: null,
-    render(node) {
-      return render(
-        <Tooltip.Root open animated={false}>
-          {node}
-        </Tooltip.Root>,
-      );
-    },
-  }));
+  it('renders children', async () => {
+    await render(
+      <Tooltip.Root open>
+        <Tooltip.Portal data-testid="portal">
+          <Tooltip.Positioner data-testid="positioner" />
+        </Tooltip.Portal>
+      </Tooltip.Root>,
+    );
+    expect(screen.getByTestId('positioner')).not.to.equal(null);
+  });
 });