[output] Skip the power limit setters when they match the defaults (#19225)

tests/component_tests/output/config/ac_dimmer_min_power_zero.yaml

@@ -0,0 +1,13 @@
+---
+esphome:
+  name: test
+
+esp32:
+  board: esp32dev
+
+output:
+  - platform: ac_dimmer
+    id: dimmer
+    gate_pin: GPIO4
+    zero_cross_pin: GPIO5
+    min_power: 0%

tests/component_tests/output/config/power_limits.yaml

@@ -0,0 +1,18 @@
+---
+esphome:
+  name: test
+
+esp32:
+  board: esp32dev
+
+output:
+  - platform: ledc
+    id: default_power
+    pin: GPIO4
+    max_power: 100%
+    min_power: 0%
+  - platform: ledc
+    id: custom_power
+    pin: GPIO5
+    max_power: 90%
+    min_power: 1%

tests/component_tests/output/test_output.py

@@ -0,0 +1,31 @@
+"""Tests for the output platform codegen."""
+
+from collections.abc import Callable
+from pathlib import Path
+
+from esphome.core import CORE
+
+
+def test_default_power_limits_are_not_emitted(
+    generate_main: Callable[[str | Path], str],
+    component_config_path: Callable[[str], Path],
+) -> None:
+    """max_power 100% and min_power 0% already live in the C++ initializers."""
+    main_cpp = generate_main(component_config_path("power_limits.yaml"))
+
+    assert "default_power->set_max_power(" not in main_cpp
+    assert "default_power->set_min_power(" not in main_cpp
+    assert "custom_power->set_max_power(0.9f);" in main_cpp
+    assert "custom_power->set_min_power(0.01f);" in main_cpp
+    assert "USE_OUTPUT_FLOAT_POWER_SCALING" in {d.name for d in CORE.defines}
+
+
+def test_default_min_power_keeps_scaling_fields(
+    generate_main: Callable[[str | Path], str],
+    component_config_path: Callable[[str], Path],
+) -> None:
+    """ac_dimmer reads min_power_ directly, so the define must stay on for min_power 0%."""
+    main_cpp = generate_main(component_config_path("ac_dimmer_min_power_zero.yaml"))
+
+    assert "dimmer->set_min_power(" not in main_cpp
+    assert "USE_OUTPUT_FLOAT_POWER_SCALING" in {d.name for d in CORE.defines}

tests/components/ac_dimmer/common.yaml

@@ -4,3 +4,4 @@ output:
     gate_pin: ${gate_pin}
     zero_cross_pin: ${zero_cross_pin}
     zero_cross_interrupt_type: ANY
+    min_power: 0%