Rename the trigger node type to debounce, migrating stored flows

The store rewrites `"type": "trigger"` to `debounce` in every published and
draft flow when it opens, bumps the version and commits once. No alias stays
behind, so `trigger` is now an unknown type.

backend/tests/flow/test_house_vocabulary.py

@@ -8,8 +8,8 @@ come up than to go down.
 
 from fluksio.flow.messages import DType, MessageSpec
 from fluksio.flow.nodes import MqttNode
+from fluksio.flow.nodes.debounce import DebounceNode
 from fluksio.flow.nodes.mqtt import topic_matches
-from fluksio.flow.nodes.trigger import TriggerNode
 
 # ── MQTT topic filters ────────────────────────────────────────────────────
 
@@ -72,7 +72,7 @@ def test_without_json_key_the_port_name_is_the_key_as_before():
     assert node.json_keys == {}
 
 
-# ── trigger: passthrough and a per-message wait ───────────────────────────
+# ── debounce: passthrough and a per-message wait ──────────────────────────
 
 
 class _Pipeline:
@@ -87,8 +87,8 @@ class _Pipeline:
         return True
 
 
-def _trigger(**params) -> tuple[TriggerNode, _Pipeline]:
-    node = TriggerNode(
+def _debounce(**params) -> tuple[DebounceNode, _Pipeline]:
+    node = DebounceNode(
         requires=[
             MessageSpec(name="run", port="run", dtype=DType.STR),
             MessageSpec(name="run_for", port="run_for", dtype=DType.FLOAT),
@@ -103,30 +103,30 @@ def _trigger(**params) -> tuple[TriggerNode, _Pipeline]:
 
 
 def test_the_incoming_value_passes_through_and_the_wait_comes_from_a_port():
-    node, pipeline = _trigger()
+    node, pipeline = _debounce()
 
-    assert node._trigger({}, run="DOWN", run_for=28.0) == {"cmd": "DOWN"}
+    assert node._debounce({}, run="DOWN", run_for=28.0) == {"cmd": "DOWN"}
     (outputs, seconds, _guard) = pipeline.deferred[-1]
     assert outputs == {"shutters.cmd": "STOP"} and seconds == 28.0
 
-    node._trigger({}, run="UP", run_for=26.0)
+    node._debounce({}, run="UP", run_for=26.0)
     assert pipeline.deferred[-1][1] == 26.0
 
 
 def test_a_second_command_invalidates_the_stop_the_first_one_scheduled():
-    node, pipeline = _trigger()
-    node._trigger({}, run="DOWN", run_for=28.0)
+    node, pipeline = _debounce()
+    node._debounce({}, run="DOWN", run_for=28.0)
     first = pipeline.deferred[-1][2]
-    node._trigger({}, run="UP", run_for=26.0)
+    node._debounce({}, run="UP", run_for=26.0)
     assert pipeline.deferred[-1][2] != first
 
 
 def test_a_wait_of_zero_sends_nothing_afterwards():
     """STOP is commanded once. Nothing follows it, forever."""
-    node, pipeline = _trigger()
-    node._trigger({}, run="DOWN", run_for=28.0)
+    node, pipeline = _debounce()
+    node._debounce({}, run="DOWN", run_for=28.0)
     scheduled = len(pipeline.deferred)
 
-    assert node._trigger({}, run="STOP", run_for=0.0) == {"cmd": "STOP"}
+    assert node._debounce({}, run="STOP", run_for=0.0) == {"cmd": "STOP"}
     assert len(pipeline.deferred) == scheduled
     assert node.recall("armed", 0) == 0

backend/tests/flow/test_node_types.py

@@ -75,7 +75,7 @@ FIXTURES: dict[str, dict] = {
         ],
         "provides": [MessageSpec(name="reading", dtype=DType.JSON)],
     },
-    "trigger": {
+    "debounce": {
         "params": {"first": True, "then": False, "wait": 120},
         "requires": [MessageSpec(name="motion", dtype=DType.BOOL)],
         "provides": [MessageSpec(name="light", dtype=DType.BOOL)],

backend/tests/flow/test_store.py

@@ -131,3 +131,31 @@ def test_renaming_onto_an_existing_name_is_refused(store: FlowStore):
         store.rename_flow("heating", "warmth")
 
     assert store.list_flows() == ["heating", "warmth"]
+
+
+def test_opening_the_store_renames_trigger_nodes_to_debounce(store: FlowStore):
+    """The old name has no alias, so what is stored under it is rewritten once."""
+    store.write_flow(
+        FlowDef(
+            name="hall",
+            nodes=[NodeDef(id="hold", type="trigger"), NodeDef(id="lamp")],
+        )
+    )
+    store.write_draft(
+        FlowDef(name="hall", nodes=[NodeDef(id="hold", type="trigger")]),
+        base_version=1,
+    )
+    commits = commit_count(store)
+
+    reopened = FlowStore(store.root)
+
+    published = reopened.read_flow("hall")
+    draft = reopened.read_flow("hall", draft=True)
+    assert [node.type for node in published.nodes] == ["debounce", "python"]
+    assert [node.type for node in draft.nodes] == ["debounce"]
+    # Bumped, so an editor holding the old draft cannot save `trigger` back.
+    assert (published.version, draft.version) == (2, 3)
+    assert commit_count(store) == commits + 1
+
+    FlowStore(store.root)
+    assert commit_count(store) == commits + 1