Introduce way to find out if composite has a descendant

This will serve eg. hiding of empty preference tab groups.

Co-authored-by: Janne Savolainen <janne.savolainen@live.fi>

Signed-off-by: Iku-turso <mikko.aspiala@gmail.com>

src/features/application-menu/main/menu-items/get-composite/composite-has-descendant/composite-has-descendant.test.ts

@@ -0,0 +1,50 @@
+/**
+ * Copyright (c) OpenLens Authors. All rights reserved.
+ * Licensed under MIT License. See LICENSE in root directory for more information.
+ */
+
+import type { Composite } from "../get-composite";
+import getComposite from "../get-composite";
+import { compositeHasDescendant } from "./composite-has-descendant";
+
+describe("composite-has-descendant, given composite with children and grand children", () => {
+  let composite: Composite<{ id: string; parentId: string | undefined }>;
+
+  beforeEach(() => {
+    const items = [
+      { id: "some-root-id", parentId: undefined },
+      { id: "some-child-item", parentId: "some-root-id" },
+
+      {
+        id: "some-grand-child-item",
+        parentId: "some-child-item",
+      },
+    ];
+
+    composite = getComposite({ source: items });
+  });
+
+  it("has a child as descendant", () => {
+    const actual = compositeHasDescendant<typeof composite["value"]>(
+      (referenceComposite) => referenceComposite.value.id === "some-child-item",
+    )(composite);
+
+    expect(actual).toBe(true);
+  });
+
+  it("has a grand child as descendant", () => {
+    const actual = compositeHasDescendant<typeof composite["value"]>(
+      (referenceComposite) => referenceComposite.value.id === "some-grand-child-item",
+    )(composite);
+
+    expect(actual).toBe(true);
+  });
+
+  it("does not have an unrelated descendant", () => {
+    const actual = compositeHasDescendant<typeof composite["value"]>(
+      (referenceComposite) => referenceComposite.value.id === "some-unknown-item",
+    )(composite);
+
+    expect(actual).toBe(false);
+  });
+});

src/features/application-menu/main/menu-items/get-composite/composite-has-descendant/composite-has-descendant.ts

@@ -0,0 +1,19 @@
+/**
+ * Copyright (c) OpenLens Authors. All rights reserved.
+ * Licensed under MIT License. See LICENSE in root directory for more information.
+ */
+import type { Composite } from "../get-composite";
+
+const compositeHasDescendant = <T>(
+  predicate: (referenceComposite: Composite<T>) => boolean,
+) => {
+  const _compositeHasDescendant = (composite: Composite<T>): boolean =>
+    predicate(composite) ||
+    !!composite.children.find((childComposite) =>
+      _compositeHasDescendant(childComposite),
+    );
+
+  return _compositeHasDescendant;
+};
+
+export { compositeHasDescendant };