[remote_transmitter] Queue RMT transmissions instead of blocking the main loop

tests/component_tests/remote_transmitter/test_queue.py

@@ -0,0 +1,33 @@
+"""max_pending defaults to twice queue_depth and may not be smaller than it."""
+
+import pytest
+
+from esphome.components.remote_transmitter import (
+    CONF_MAX_PENDING,
+    CONF_QUEUE_DEPTH,
+    _validate_queue,
+)
+import esphome.config_validation as cv
+
+
+def test_max_pending_defaults_to_twice_queue_depth() -> None:
+    config = {CONF_QUEUE_DEPTH: 4}
+    _validate_queue(config)
+    assert config[CONF_MAX_PENDING] == 8
+
+
+def test_max_pending_explicit_is_kept() -> None:
+    config = {CONF_QUEUE_DEPTH: 4, CONF_MAX_PENDING: 4}
+    _validate_queue(config)
+    assert config[CONF_MAX_PENDING] == 4
+
+
+def test_max_pending_below_queue_depth_is_rejected() -> None:
+    with pytest.raises(cv.Invalid, match="max_pending must be at least queue_depth"):
+        _validate_queue({CONF_QUEUE_DEPTH: 4, CONF_MAX_PENDING: 2})
+
+
+def test_no_queue_depth_without_rmt() -> None:
+    config: dict[str, int] = {}
+    _validate_queue(config)
+    assert CONF_MAX_PENDING not in config

tests/components/remote_transmitter/esp32-common.yaml

@@ -5,6 +5,8 @@ remote_transmitter:
     non_blocking: true
     clock_resolution: ${clock_resolution}
     rmt_symbols: ${rmt_symbols}
+    queue_depth: 4
+    max_pending: 8
 
 packages:
   buttons: !include common-buttons.yaml

tests/components/remote_transmitter/validate-queue-depth-1.esp32-idf.yaml

@@ -0,0 +1,12 @@
+substitutions:
+  pin: GPIO2
+
+remote_transmitter:
+  - id: xmitr
+    pin: ${pin}
+    carrier_duty_percent: 50%
+    non_blocking: true
+    queue_depth: 1
+
+packages:
+  buttons: !include common-buttons.yaml