chore: refactoring and tests (#12468)

packages/app/src/components/prompt-input/editor-dom.test.ts

@@ -0,0 +1,51 @@
+import { describe, expect, test } from "bun:test"
+import { createTextFragment, getCursorPosition, getNodeLength, getTextLength, setCursorPosition } from "./editor-dom"
+
+describe("prompt-input editor dom", () => {
+  test("createTextFragment preserves newlines with br and zero-width placeholders", () => {
+    const fragment = createTextFragment("foo\n\nbar")
+    const container = document.createElement("div")
+    container.appendChild(fragment)
+
+    expect(container.childNodes.length).toBe(5)
+    expect(container.childNodes[0]?.textContent).toBe("foo")
+    expect((container.childNodes[1] as HTMLElement).tagName).toBe("BR")
+    expect(container.childNodes[2]?.textContent).toBe("\u200B")
+    expect((container.childNodes[3] as HTMLElement).tagName).toBe("BR")
+    expect(container.childNodes[4]?.textContent).toBe("bar")
+  })
+
+  test("length helpers treat breaks as one char and ignore zero-width chars", () => {
+    const container = document.createElement("div")
+    container.appendChild(document.createTextNode("ab\u200B"))
+    container.appendChild(document.createElement("br"))
+    container.appendChild(document.createTextNode("cd"))
+
+    expect(getNodeLength(container.childNodes[0]!)).toBe(2)
+    expect(getNodeLength(container.childNodes[1]!)).toBe(1)
+    expect(getTextLength(container)).toBe(5)
+  })
+
+  test("setCursorPosition and getCursorPosition round-trip with pills and breaks", () => {
+    const container = document.createElement("div")
+    const pill = document.createElement("span")
+    pill.dataset.type = "file"
+    pill.textContent = "@file"
+    container.appendChild(document.createTextNode("ab"))
+    container.appendChild(pill)
+    container.appendChild(document.createElement("br"))
+    container.appendChild(document.createTextNode("cd"))
+    document.body.appendChild(container)
+
+    setCursorPosition(container, 2)
+    expect(getCursorPosition(container)).toBe(2)
+
+    setCursorPosition(container, 7)
+    expect(getCursorPosition(container)).toBe(7)
+
+    setCursorPosition(container, 8)
+    expect(getCursorPosition(container)).toBe(8)
+
+    container.remove()
+  })
+})