[log] Detect early log calls before logger init and optimize hot path (#14538)

tests/component_tests/logger/test_logger.py

@@ -0,0 +1,50 @@
+"""Tests for the logger component."""
+
+import re
+
+
+def test_logger_pre_setup_before_other_components(generate_main):
+    """Logger::pre_setup() must be called before any other component is created.
+
+    Log functions call global_logger->log_vprintf_() without a null check,
+    so global_logger must be set before anything can log.
+    """
+    main_cpp = generate_main("tests/component_tests/logger/test_logger.yaml")
+
+    # Find the logger's pre_setup() call specifically
+    logger_pre_setup = re.search(r"logger_logger->pre_setup\(\)", main_cpp)
+    if logger_pre_setup is None:
+        # Fall back to finding any logger-related pre_setup
+        logger_pre_setup = re.search(r"logger\w*->pre_setup\(\)", main_cpp)
+    assert logger_pre_setup is not None, (
+        "Logger pre_setup() not found in generated code"
+    )
+
+    # Find all "new " allocations (component creation)
+    new_allocations = list(re.finditer(r"\bnew [\w:]+", main_cpp))
+    assert len(new_allocations) > 0, "No component allocations found"
+
+    # Separate logger and non-logger allocations
+    logger_allocs = [a for a in new_allocations if "logger" in a.group().lower()]
+    non_logger_allocs = [
+        a
+        for a in new_allocations
+        if "logger" not in a.group().lower()
+        # Skip placement new for App
+        and "(&App)" not in main_cpp[max(0, a.start() - 5) : a.start()]
+    ]
+
+    assert len(logger_allocs) > 0, (
+        f"Logger allocation not found in: {[a.group() for a in new_allocations]}"
+    )
+    assert len(non_logger_allocs) > 0, (
+        "No non-logger component allocations found — "
+        "add a component to test_logger.yaml so the ordering check is meaningful"
+    )
+
+    # All non-logger allocations must appear after logger pre_setup()
+    for alloc in non_logger_allocs:
+        assert alloc.start() > logger_pre_setup.start(), (
+            f"Component allocation '{alloc.group()}' at position {alloc.start()} "
+            f"appears before logger pre_setup() at position {logger_pre_setup.start()}"
+        )

tests/component_tests/logger/test_logger.yaml

@@ -0,0 +1,14 @@
+---
+esphome:
+  name: test
+
+esp8266:
+  board: d1_mini_lite
+
+logger:
+  level: DEBUG
+
+# Need at least one non-logger component so the ordering test
+# can verify that logger pre_setup() comes before other allocations.
+preferences:
+  flash_write_interval: 1min

tests/components/main.cpp

@@ -1,5 +1,7 @@
 #include <gtest/gtest.h>
 
+#include "esphome/components/logger/logger.h"
+
 /*
 This special main.cpp replaces the default one.
 It will run all the Google Tests found in all compiled cpp files and then exit with the result
@@ -18,6 +20,12 @@ void original_setup() {
 }
 
 void setup() {
+  // Log functions call global_logger->log_vprintf_() without a null check,
+  // so we must set up a Logger before any test that triggers logging.
+  static esphome::logger::Logger test_logger(0);
+  test_logger.set_log_level(ESPHOME_LOG_LEVEL);
+  test_logger.pre_setup();
+
   ::testing::InitGoogleTest();
   int exit_code = RUN_ALL_TESTS();
   exit(exit_code);

tests/integration/conftest.py

@@ -193,6 +193,7 @@ async def yaml_config(request: pytest.FixtureRequest, unused_tcp_port: int) -> s
             "  platformio_options:\n"
             "    build_flags:\n"
             '      - "-DDEBUG"  # Enable assert() statements\n'
+            '      - "-DESPHOME_DEBUG"  # Enable ESPHOME_DEBUG_ASSERT checks\n'
             '      - "-DESPHOME_DEBUG_API"  # Enable API protocol asserts\n'
             '      - "-g"       # Add debug symbols',
         )