[remote_receiver] Size the RMT ring buffer from receive symbols by default (#19100)

tests/component_tests/remote_receiver/config/receiver_buffer_size.yaml

@@ -0,0 +1,10 @@
+esphome:
+  name: test
+
+esp32:
+  board: esp32dev
+
+remote_receiver:
+  - id: rcvr
+    pin: GPIO4
+    buffer_size: 2kb

tests/component_tests/remote_receiver/config/receiver_esp32_c2.yaml

@@ -0,0 +1,12 @@
+esphome:
+  name: test
+
+esp32:
+  board: esp32-c2-devkitm-1
+  variant: esp32c2
+  framework:
+    type: esp-idf
+
+remote_receiver:
+  - id: rcvr
+    pin: GPIO4

tests/component_tests/remote_receiver/config/receiver_esp8266.yaml

@@ -0,0 +1,9 @@
+esphome:
+  name: test
+
+esp8266:
+  board: d1_mini
+
+remote_receiver:
+  - id: rcvr
+    pin: GPIO4

tests/component_tests/remote_receiver/test_buffer_size.py

@@ -0,0 +1,28 @@
+"""buffer_size reaches the receiver when set, and always on the pulse ring targets."""
+
+from collections.abc import Callable
+from pathlib import Path
+
+
+def test_explicit_buffer_size_is_passed_through(
+    generate_main: Callable[[str | Path], str],
+    component_config_path: Callable[[str], Path],
+) -> None:
+    main_cpp = generate_main(component_config_path("receiver_buffer_size.yaml"))
+    assert "rcvr->set_buffer_size(2000);" in main_cpp
+
+
+def test_pulse_ring_target_keeps_a_default(
+    generate_main: Callable[[str | Path], str],
+    component_config_path: Callable[[str], Path],
+) -> None:
+    main_cpp = generate_main(component_config_path("receiver_esp8266.yaml"))
+    assert "rcvr->set_buffer_size(1000);" in main_cpp
+
+
+def test_esp32_variant_without_rmt_keeps_a_default(
+    generate_main: Callable[[str | Path], str],
+    component_config_path: Callable[[str], Path],
+) -> None:
+    main_cpp = generate_main(component_config_path("receiver_esp32_c2.yaml"))
+    assert "rcvr->set_buffer_size(1000);" in main_cpp

tests/component_tests/remote_receiver/test_slot_counts.py

@@ -27,7 +27,9 @@ def test_bare_receiver_emits_no_counts(
     generate_main: Callable[[str | Path], str],
     component_config_path: Callable[[str], Path],
 ) -> None:
-    generate_main(component_config_path("receiver_bare.yaml"))
+    main_cpp = generate_main(component_config_path("receiver_bare.yaml"))
+    # the RMT ring is sized in setup() unless buffer_size is set
+    assert "set_buffer_size" not in main_cpp
     assert get_define_value("REMOTE_BASE_DUMPER_COUNT") is None
     assert get_define_value("REMOTE_BASE_LISTENER_COUNT") is None