Test: reproduce inconsistent raw text slot diagnostics

src/test/scala/com/raquo/laminar/tests/TextInserterSlotMoveSpec.scala

@@ -0,0 +1,119 @@
+package com.raquo.laminar.tests
+
+import com.raquo.laminar.api.L._
+import com.raquo.laminar.inserters.Inserter
+import com.raquo.laminar.nodes.Slot
+import com.raquo.laminar.utils.UnitSpec
+
+/** `text <--` never slots its text node: named slots only accept elements, so a `text <--` item
+  * inside a slotted `children <--` list renders quietly into the default slot. Relocating that item
+  * must be just as quiet – a move is not allowed to report an error that the original placement
+  * did not.
+  */
+class TextInserterSlotMoveSpec extends UnitSpec {
+
+  it("a `text <--` item stolen between two identically-slotted lists reports no error and stays live") {
+    val tracker = createEventTracker()
+    val textVar = Var("hi")
+    val items1 = Var[List[Inserter]](Nil)
+    val items2 = Var[List[Inserter]](Nil)
+    val dynText: Inserter = tracker.text("t", textVar.signal)
+
+    mount(
+      div(
+        div("L1", new Slot("prefix")(children <-- items1.signal)),
+        div("L2", new Slot("prefix")(children <-- items2.signal))
+      )
+    )
+
+    withClue("first placement in the slotted L1 renders quietly (text is never slotted):") {
+      withCollectedAirstreamErrors { errors =>
+        items1.set(List(dynText))
+        assert(errors.isEmpty, s"placing the text item reported: ${errors.mkString("; ")}")
+      }
+      tracker.assertEvents(_.textUpdated("t", "hi")).clear()
+      expectNode(
+        div.of(
+          div.of("L1", sentinel, sentinel, "hi", sentinel, sentinel),
+          div.of("L2", sentinel, sentinel)
+        )
+      )
+    }
+
+    withClue("add-first steal into the slotted L2 must be just as quiet as the placement:") {
+      withCollectedAirstreamErrors { errors =>
+        items2.set(List(dynText))
+        items1.set(Nil)
+        assert(errors.isEmpty, s"moving the text item reported: ${errors.mkString("; ")}")
+      }
+      tracker.assertNoEvents.clear()
+      expectNode(
+        div.of(
+          div.of("L1", sentinel, sentinel),
+          div.of("L2", sentinel, sentinel, "hi", sentinel, sentinel)
+        )
+      )
+    }
+
+    withClue("still live in L2:") {
+      textVar.set("bye")
+      tracker.assertEvents(_.textUpdated("t", "bye")).clear()
+      expectNode(
+        div.of(
+          div.of("L1", sentinel, sentinel),
+          div.of("L2", sentinel, sentinel, "bye", sentinel, sentinel)
+        )
+      )
+    }
+  }
+
+  it("a `text <--` item re-stolen between two differently-slotted sibling lists under one parent reports no error") {
+    // Same-parent layout: the steal-back is a raw same-parent reposition followed by a slot
+    // re-affirm, a different path than the cross-parent transfer above. Both must stay quiet.
+    val tracker = createEventTracker()
+    val textVar = Var("hi")
+    val items1 = Var[List[Inserter]](Nil)
+    val items2 = Var[List[Inserter]](Nil)
+    val dynText: Inserter = tracker.text("t", textVar.signal)
+
+    mount(
+      div(
+        new Slot("a")(children <-- items1.signal),
+        new Slot("b")(children <-- items2.signal)
+      )
+    )
+
+    withClue("first placement in the `a`-slotted list renders quietly:") {
+      withCollectedAirstreamErrors { errors =>
+        items1.set(List(dynText))
+        assert(errors.isEmpty, s"placing the text item reported: ${errors.mkString("; ")}")
+      }
+      tracker.assertEvents(_.textUpdated("t", "hi")).clear()
+      expectNode(div.of(sentinel, sentinel, "hi", sentinel, sentinel, sentinel, sentinel))
+    }
+
+    withClue("steal into the `b`-slotted sibling list: quiet:") {
+      withCollectedAirstreamErrors { errors =>
+        items2.set(List(dynText))
+        assert(errors.isEmpty, s"stealing the text item reported: ${errors.mkString("; ")}")
+      }
+      tracker.assertNoEvents.clear()
+      expectNode(div.of(sentinel, sentinel, sentinel, sentinel, "hi", sentinel, sentinel))
+    }
+
+    withClue("steal back into the `a`-slotted list (stale re-emit): quiet:") {
+      withCollectedAirstreamErrors { errors =>
+        items1.set(List(dynText))
+        assert(errors.isEmpty, s"stealing the text item back reported: ${errors.mkString("; ")}")
+      }
+      tracker.assertNoEvents.clear()
+      expectNode(div.of(sentinel, sentinel, "hi", sentinel, sentinel, sentinel, sentinel))
+    }
+
+    withClue("still live after the round trip:") {
+      textVar.set("bye")
+      tracker.assertEvents(_.textUpdated("t", "bye")).clear()
+      expectNode(div.of(sentinel, sentinel, "bye", sentinel, sentinel, sentinel, sentinel))
+    }
+  }
+}