Fix e2e tests on Mac (#9401)

Some e2e tests (about leaving nodes) were always failing on my machine because of the race condition in the tests. The issue was caused by edges positions lagging behind for a few frames when switching Enso functions, which caused incorrect handling of clicks in the test code.

Now we wait for edges being initialized *and* node sizes being updated.

Thanks to @farmaazon for helping with debugging.

app/gui2/e2e/actions.ts

@@ -18,6 +18,10 @@ export async function goToGraph(page: Page) {
 }
 
 export async function expectNodePositionsInitialized(page: Page, yPos: number) {
+  // Wait until edges are initialized and displayed correctly.
+  await expect(page.getByTestId('broken-edge')).toHaveCount(0)
+  // Wait until node sizes are initialized.
+  await expect(locate.graphNode(page).first().locator('.bgFill')).toBeVisible()
   // TODO: The yPos should not need to be a variable. Instead, first automatically positioned nodes
   // should always have constant known position. This is a bug caused by incorrect layout after
   // entering a function. To be fixed with #9255

app/gui2/src/components/GraphEditor/GraphEdge.vue

@@ -79,6 +79,15 @@ const sourceRect = computed<Rect | undefined>(() => {
   }
 })
 
+/** Edges which do not have `sourceRect` and `targetPos` initialized are marked by a special
+ * `broken-edge` data-testid, for debugging and e2e test purposes. */
+const edgeIsBroken = computed(
+  () =>
+    sourceRect.value == null ||
+    targetPos.value == null ||
+    (sourceRect.value.pos.equals(targetPos.value) && sourceRect.value.size.equals(Vec2.Zero)),
+)
+
 type NodeMask = {
   id: string
   rect: Rect
@@ -508,6 +517,7 @@ const connected = computed(() => isConnected(props.edge))
         class="edge io"
         :data-source-node-id="sourceNode"
         :data-target-node-id="targetNode"
+        :data-testid="edgeIsBroken ? 'broken-edge' : null"
         @pointerdown.stop="click"
         @pointerenter="hovered = true"
         @pointerleave="hovered = false"