[fan] Cover fan.turn_on inside on_preset_set (StringRef Ts) in tests

tests/components/fan/common.yaml

@@ -9,6 +9,14 @@ fan:
     has_oscillating: true
     has_direction: true
     speed_count: 3
+    # Exercise fan.turn_on inside a trigger whose Ts pack is non-empty
+    # (StringRef from on_preset_set) so the apply-lambda + inner-lambda
+    # codegen runs through the cvref-normalized path.
+    on_preset_set:
+      then:
+        - fan.turn_on:
+            id: test_fan
+            speed: !lambda "return x.empty() ? 1 : 3;"
 
 # Test lambdas using get_preset_mode() which returns StringRef
 # These examples match the migration guide in the PR description
@@ -89,8 +97,11 @@ button:
           id: test_fan
           speed: !lambda 'return 1;'
 
-# Exercise fan.turn_on inside a trigger with non-empty Ts (number on_value
+# Exercise fan.turn_on inside triggers with non-empty Ts:
-# passes float).
+#  - number.on_value: Ts = float (Python value type; previously raised
+#    AttributeError on .operator("const"))
+#  - fan.on_preset_set: Ts = StringRef (already a value-type wrapper around
+#    a const char * + size; tests the cvref-normalized inner-lambda path)
 number:
   - platform: template
     id: fan_speed_number