From 597e433a0fe40a01060ec9ddce3c7fd38de16b4e Mon Sep 17 00:00:00 2001
From: Eberhard Beilharz <eb1@sil.org>
Date: Thu, 20 Nov 2025 16:03:17 +0100
Subject: [PATCH] test(web): add unit tests for `nestedInstanceOf`

Also rename file `utils.ts` to `nestedInstanceOf.ts`.

Test-bot: skip
---
 .../createTextStoreForElement.ts              |  2 +-
 .../engine/src/element-text-stores/index.ts   |  2 +-
 .../{utils.ts => nestedInstanceOf.ts}         |  0
 .../nestedInstanceOf.tests.ts                 | 47 +++++++++++++++++++
 4 files changed, 49 insertions(+), 2 deletions(-)
 rename web/src/engine/src/element-text-stores/{utils.ts => nestedInstanceOf.ts} (100%)
 create mode 100644 web/src/test/auto/dom/cases/element-text-stores/nestedInstanceOf.tests.ts

diff --git a/web/src/engine/src/element-text-stores/createTextStoreForElement.ts b/web/src/engine/src/element-text-stores/createTextStoreForElement.ts
index 0285d55b3b..06dfe1b005 100644
--- a/web/src/engine/src/element-text-stores/createTextStoreForElement.ts
+++ b/web/src/engine/src/element-text-stores/createTextStoreForElement.ts
@@ -3,7 +3,7 @@ import { InputElementTextStore } from './inputTextStore.js';
 import { TextAreaElementTextStore } from './textareaTextStore.js';
 import { DesignIFrameElementTextStore } from './designIFrameTextStore.js';
 import { ContentEditableElementTextStore } from './contentEditableTextStore.js';
-import { nestedInstanceOf } from './utils.js';
+import { nestedInstanceOf } from './nestedInstanceOf.js';
 
 export function createTextStoreForElement(e: HTMLElement): AbstractElementTextStore<any> {
   // Complex type scoping is implemented here so that kmwutils.ts is not a dependency for test compilations.
diff --git a/web/src/engine/src/element-text-stores/index.ts b/web/src/engine/src/element-text-stores/index.ts
index b8c0ac2147..809923a8c8 100644
--- a/web/src/engine/src/element-text-stores/index.ts
+++ b/web/src/engine/src/element-text-stores/index.ts
@@ -4,4 +4,4 @@ export { DesignIFrameElementTextStore } from './designIFrameTextStore.js';
 export { InputElementTextStore } from './inputTextStore.js';
 export { AbstractElementTextStore } from './abstractElementTextStore.js';
 export { TextAreaElementTextStore } from './textareaTextStore.js';
-export { nestedInstanceOf } from './utils.js';
\ No newline at end of file
+export { nestedInstanceOf } from './nestedInstanceOf.js';
\ No newline at end of file
diff --git a/web/src/engine/src/element-text-stores/utils.ts b/web/src/engine/src/element-text-stores/nestedInstanceOf.ts
similarity index 100%
rename from web/src/engine/src/element-text-stores/utils.ts
rename to web/src/engine/src/element-text-stores/nestedInstanceOf.ts
diff --git a/web/src/test/auto/dom/cases/element-text-stores/nestedInstanceOf.tests.ts b/web/src/test/auto/dom/cases/element-text-stores/nestedInstanceOf.tests.ts
new file mode 100644
index 0000000000..d2833f3ce7
--- /dev/null
+++ b/web/src/test/auto/dom/cases/element-text-stores/nestedInstanceOf.tests.ts
@@ -0,0 +1,47 @@
+/*
+ * Keyman is copyright (C) SIL Global. MIT License.
+ */
+import { assert } from 'chai';
+import { nestedInstanceOf } from 'keyman/engine/element-text-stores';
+
+describe('nestedInstanceOf', () => {
+  it('returns false for null input', () => {
+    assert.strictEqual(nestedInstanceOf(null as any, 'HTMLElement'), false);
+  });
+
+  it('returns true for Window object when className is "Window"', () => {
+    assert.strictEqual(nestedInstanceOf(window as any, 'Window'), true);
+  });
+
+  it('returns false for Window object when className is not "Window"', () => {
+    assert.strictEqual(nestedInstanceOf(window as any, 'Document'), false);
+  });
+
+  it('returns true for Document object when className is "Document"', () => {
+    assert.strictEqual(nestedInstanceOf(document as any, 'Document'), true);
+  });
+
+  it('returns false for Document object when className is not "Document"', () => {
+    assert.strictEqual(nestedInstanceOf(document as any, 'HTMLElement'), false);
+  });
+
+  it('returns true for HTMLElement when className is "HTMLElement"', () => {
+    const elem = document.createElement('div');
+    assert.strictEqual(nestedInstanceOf(elem, 'HTMLElement'), true);
+  });
+
+  it('returns false for HTMLElement when className is "HTMLInputElement"', () => {
+    const elem = document.createElement('div');
+    assert.strictEqual(nestedInstanceOf(elem, 'HTMLInputElement'), false);
+  });
+
+  it('returns true for HTMLInputElement when className is "HTMLInputElement"', () => {
+    const input = document.createElement('input');
+    assert.strictEqual(nestedInstanceOf(input, 'HTMLInputElement'), true);
+  });
+
+  it('returns false for unknown className', () => {
+    const elem = document.createElement('div');
+    assert.strictEqual(nestedInstanceOf(elem, 'NonExistentClass'), false);
+  });
+});