[espidf] Honor compile_process_limit in native ESP-IDF builds (#17857)

tests/unit_tests/test_espidf_toolchain.py

@@ -10,7 +10,12 @@ from unittest.mock import patch
 
 import pytest
 
-from esphome.const import CONF_FRAMEWORK, CONF_SOURCE
+from esphome.const import (
+    CONF_COMPILE_PROCESS_LIMIT,
+    CONF_ESPHOME,
+    CONF_FRAMEWORK,
+    CONF_SOURCE,
+)
 from esphome.core import CORE, EsphomeError
 from esphome.espidf import toolchain
 
@@ -309,6 +314,58 @@ def test_get_cmake_output_missing_build_does_not_resolve_idf_env(
     mock_run.assert_not_called()
 
 
+def test_run_idf_py_jobs_sets_build_jobs_env(setup_core: Path) -> None:
+    """The jobs argument is exported to idf.py as IDF_PY_BUILD_JOBS."""
+    _setup_build(setup_core)
+
+    with (
+        patch.object(toolchain, "_get_idf_path", return_value=Path("/idf")),
+        patch.object(toolchain, "_get_idf_env", return_value={"PATH": "/bin"}),
+        patch.object(toolchain, "_get_idf_tool", return_value="python"),
+        patch.object(toolchain.subprocess, "run") as mock_run,
+    ):
+        mock_run.return_value.returncode = 0
+
+        toolchain.run_idf_py("build", jobs=2)
+        env = mock_run.call_args.kwargs["env"]
+        assert env["IDF_PY_BUILD_JOBS"] == "2"
+        assert env["PATH"] == "/bin"
+
+        toolchain.run_idf_py("build")
+        env = mock_run.call_args.kwargs["env"]
+        assert "IDF_PY_BUILD_JOBS" not in env
+
+
+def test_run_compile_passes_compile_process_limit(setup_core: Path) -> None:
+    """compile_process_limit is forwarded to run_idf_py as the job limit."""
+    _setup_build(setup_core)
+    config = {CONF_ESPHOME: {CONF_COMPILE_PROCESS_LIMIT: 1}}
+
+    with (
+        patch.object(toolchain, "need_reconfigure", return_value=False),
+        patch.object(toolchain, "run_idf_py", return_value=0) as mock_run,
+        patch.object(toolchain, "print_summary"),
+    ):
+        assert toolchain.run_compile(config, verbose=False) == 0
+
+    mock_run.assert_called_once_with("build", "size", jobs=1)
+
+
+def test_run_compile_without_compile_process_limit(setup_core: Path) -> None:
+    """When no compile_process_limit is set, no job limit is passed to idf.py."""
+    _setup_build(setup_core)
+    config = {CONF_ESPHOME: {}}
+
+    with (
+        patch.object(toolchain, "need_reconfigure", return_value=False),
+        patch.object(toolchain, "run_idf_py", return_value=0) as mock_run,
+        patch.object(toolchain, "print_summary"),
+    ):
+        assert toolchain.run_compile(config, verbose=False) == 0
+
+    mock_run.assert_called_once_with("build", "size", jobs=None)
+
+
 def test_get_core_framework_version_from_core_data():
     """The version is read from CORE.data when validation populated it."""
     from esphome.components.esp32.const import KEY_ESP32, KEY_IDF_VERSION