increase test coverage

extend test coverage

tests/e2e/unit/svgcore-history.spec.js

@@ -0,0 +1,46 @@
+import { test, expect } from '../fixtures.js'
+
+test.describe('SVG core history/draw smoke', () => {
+  test.beforeEach(async ({ page }) => {
+    await page.goto('/tests/unit-harness.html')
+    await page.waitForFunction(() => Boolean(window.svgHarness))
+  })
+
+  test('UndoManager push/undo/redo stack sizes update', async ({ page }) => {
+    const stacks = await page.evaluate(() => {
+      const { history } = window.svgHarness
+      class DummyCommand extends history.Command {
+        constructor (text) {
+          super()
+          this.text = text
+        }
+
+        apply () {}
+        unapply () {}
+      }
+      const um = new history.UndoManager()
+      um.addCommandToHistory(new DummyCommand('one'))
+      um.addCommandToHistory(new DummyCommand('two'))
+      const beforeUndo = { undo: um.getUndoStackSize(), redo: um.getRedoStackSize() }
+      um.undo()
+      const afterUndo = { undo: um.getUndoStackSize(), redo: um.getRedoStackSize() }
+      um.redo()
+      const afterRedo = { undo: um.getUndoStackSize(), redo: um.getRedoStackSize() }
+      return { beforeUndo, afterUndo, afterRedo, nextUndo: um.getNextUndoCommandText(), nextRedo: um.getNextRedoCommandText() }
+    })
+    expect(stacks.beforeUndo.undo).toBe(2)
+    expect(stacks.beforeUndo.redo).toBe(0)
+    expect(stacks.afterUndo.undo).toBe(1)
+    expect(stacks.afterUndo.redo).toBe(1)
+    expect(stacks.afterRedo.undo).toBe(2)
+    expect(stacks.nextUndo.length).toBeGreaterThan(0)
+  })
+
+  test('draw module exports expected functions', async ({ page }) => {
+    const exports = await page.evaluate(() => {
+      const { draw } = window.svgHarness
+      return ['init', 'randomizeIds', 'createLayer'].map(fn => typeof draw[fn] === 'function')
+    })
+    exports.forEach(v => expect(v).toBe(true))
+  })
+})