[core] Remove object_id RAM storage - no longer in hot path after #12627

tests/integration/fixtures/fnv1_hash_object_id.yaml

@@ -0,0 +1,76 @@
+esphome:
+  name: fnv1-hash-object-id-test
+  platformio_options:
+    build_flags:
+      - "-DDEBUG"
+  on_boot:
+    - lambda: |-
+        using esphome::fnv1_hash_object_id;
+
+        // Test basic lowercase (hash matches Python fnv1_hash_object_id("foo"))
+        uint32_t hash_foo = fnv1_hash_object_id("foo", 3);
+        if (hash_foo == 0x408f5e13) {
+          ESP_LOGI("FNV1_OID", "foo PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "foo FAILED: 0x%08x != 0x408f5e13", hash_foo);
+        }
+
+        // Test uppercase conversion (should match lowercase)
+        uint32_t hash_Foo = fnv1_hash_object_id("Foo", 3);
+        if (hash_Foo == 0x408f5e13) {
+          ESP_LOGI("FNV1_OID", "upper PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "upper FAILED: 0x%08x != 0x408f5e13", hash_Foo);
+        }
+
+        // Test space to underscore conversion ("foo bar" -> "foo_bar")
+        uint32_t hash_space = fnv1_hash_object_id("foo bar", 7);
+        if (hash_space == 0x3ae35aa1) {
+          ESP_LOGI("FNV1_OID", "space PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "space FAILED: 0x%08x != 0x3ae35aa1", hash_space);
+        }
+
+        // Test underscore preserved ("foo_bar")
+        uint32_t hash_underscore = fnv1_hash_object_id("foo_bar", 7);
+        if (hash_underscore == 0x3ae35aa1) {
+          ESP_LOGI("FNV1_OID", "underscore PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "underscore FAILED: 0x%08x != 0x3ae35aa1", hash_underscore);
+        }
+
+        // Test hyphen preserved ("foo-bar")
+        uint32_t hash_hyphen = fnv1_hash_object_id("foo-bar", 7);
+        if (hash_hyphen == 0x438b12e3) {
+          ESP_LOGI("FNV1_OID", "hyphen PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "hyphen FAILED: 0x%08x != 0x438b12e3", hash_hyphen);
+        }
+
+        // Test special chars become underscore ("foo!bar" -> "foo_bar")
+        uint32_t hash_special = fnv1_hash_object_id("foo!bar", 7);
+        if (hash_special == 0x3ae35aa1) {
+          ESP_LOGI("FNV1_OID", "special PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "special FAILED: 0x%08x != 0x3ae35aa1", hash_special);
+        }
+
+        // Test complex name ("My Sensor Name" -> "my_sensor_name")
+        uint32_t hash_complex = fnv1_hash_object_id("My Sensor Name", 14);
+        if (hash_complex == 0x2760962a) {
+          ESP_LOGI("FNV1_OID", "complex PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "complex FAILED: 0x%08x != 0x2760962a", hash_complex);
+        }
+
+        // Test empty string returns FNV1_OFFSET_BASIS
+        uint32_t hash_empty = fnv1_hash_object_id("", 0);
+        if (hash_empty == 0x811c9dc5) {
+          ESP_LOGI("FNV1_OID", "empty PASSED");
+        } else {
+          ESP_LOGE("FNV1_OID", "empty FAILED: 0x%08x != 0x811c9dc5", hash_empty);
+        }
+
+host:
+api:
+logger:

tests/integration/test_fnv1_hash_object_id.py

@@ -0,0 +1,75 @@
+"""Integration test for fnv1_hash_object_id function.
+
+This test verifies that the C++ fnv1_hash_object_id() function in
+esphome/core/helpers.h produces the same hash values as the Python
+fnv1_hash_object_id() function in esphome/helpers.py.
+
+If this test fails, one of the implementations has diverged and needs
+to be updated to match the other.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import re
+
+import pytest
+
+from .types import APIClientConnectedFactory, RunCompiledFunction
+
+
+@pytest.mark.asyncio
+async def test_fnv1_hash_object_id(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test that C++ fnv1_hash_object_id matches Python implementation."""
+
+    test_results: dict[str, str] = {}
+    all_tests_complete = asyncio.Event()
+    expected_tests = {
+        "foo",
+        "upper",
+        "space",
+        "underscore",
+        "hyphen",
+        "special",
+        "complex",
+        "empty",
+    }
+
+    def on_log_line(line: str) -> None:
+        """Capture log lines with test results."""
+        # Strip ANSI escape codes
+        clean_line = re.sub(r"\x1b\[[0-9;]*m", "", line)
+        # Look for our test result messages
+        # Format: "[timestamp][level][FNV1_OID:line]: test_name PASSED"
+        match = re.search(r"\[FNV1_OID:\d+\]:\s+(\w+)\s+(PASSED|FAILED)", clean_line)
+        if match:
+            test_name = match.group(1)
+            result = match.group(2)
+            test_results[test_name] = result
+            if set(test_results.keys()) >= expected_tests:
+                all_tests_complete.set()
+
+    async with (
+        run_compiled(yaml_config, line_callback=on_log_line),
+        api_client_connected() as client,
+    ):
+        device_info = await client.device_info()
+        assert device_info is not None
+        assert device_info.name == "fnv1-hash-object-id-test"
+
+        # Wait for all tests to complete or timeout
+        try:
+            await asyncio.wait_for(all_tests_complete.wait(), timeout=2.0)
+        except TimeoutError:
+            pytest.fail(f"Tests timed out. Got results for: {set(test_results.keys())}")
+
+        # Verify all tests passed
+        for test_name in expected_tests:
+            assert test_name in test_results, f"{test_name} test not found"
+            assert test_results[test_name] == "PASSED", (
+                f"{test_name} test failed - C++ and Python hash mismatch"
+            )

tests/unit_tests/test_helpers.py

@@ -279,6 +279,77 @@ def test_sanitize(text, expected):
     assert actual == expected
 
 
+@pytest.mark.parametrize(
+    ("name", "expected_hash"),
+    (
+        # Basic strings - hash of snake_case(sanitize(name))
+        ("foo", 0x408F5E13),
+        ("Foo", 0x408F5E13),  # Same as "foo" (lowercase)
+        ("FOO", 0x408F5E13),  # Same as "foo" (lowercase)
+        # Spaces become underscores
+        ("foo bar", 0x3AE35AA1),  # Transforms to "foo_bar"
+        ("Foo Bar", 0x3AE35AA1),  # Same (lowercase + underscore)
+        # Already snake_case
+        ("foo_bar", 0x3AE35AA1),
+        # Special chars become underscores
+        ("foo!bar", 0x3AE35AA1),  # Transforms to "foo_bar"
+        ("foo@bar", 0x3AE35AA1),  # Transforms to "foo_bar"
+        # Hyphens are preserved
+        ("foo-bar", 0x438B12E3),
+        # Numbers are preserved
+        ("foo123", 0xF3B0067D),
+        # Empty string
+        ("", 0x811C9DC5),  # FNV1_OFFSET_BASIS (no chars processed)
+        # Single char
+        ("a", 0x050C5D7E),
+        # Mixed case and spaces
+        ("My Sensor Name", 0x2760962A),  # Transforms to "my_sensor_name"
+    ),
+)
+def test_fnv1_hash_object_id(name, expected_hash):
+    """Test fnv1_hash_object_id produces expected hashes.
+
+    These expected values were computed to match the C++ implementation
+    in esphome/core/helpers.h. If this test fails after modifying either
+    implementation, ensure both Python and C++ versions stay in sync.
+    """
+    actual = helpers.fnv1_hash_object_id(name)
+
+    assert actual == expected_hash
+
+
+def _fnv1_hash_py(s: str) -> int:
+    """Python implementation of FNV-1 hash for verification."""
+    hash_val = 2166136261  # FNV1_OFFSET_BASIS
+    for c in s:
+        hash_val = (hash_val * 16777619) & 0xFFFFFFFF  # FNV1_PRIME
+        hash_val ^= ord(c)
+    return hash_val
+
+
+@pytest.mark.parametrize(
+    "name",
+    (
+        "Simple",
+        "With Space",
+        "MixedCase",
+        "special!@#chars",
+        "already_snake_case",
+        "123numbers",
+    ),
+)
+def test_fnv1_hash_object_id_matches_manual_calculation(name):
+    """Verify fnv1_hash_object_id matches snake_case + sanitize + standard FNV-1."""
+    # Manual calculation: snake_case -> sanitize -> fnv1_hash
+    transformed = helpers.sanitize(helpers.snake_case(name))
+    expected = _fnv1_hash_py(transformed)
+
+    # Direct calculation via fnv1_hash_object_id
+    actual = helpers.fnv1_hash_object_id(name)
+
+    assert actual == expected
+
+
 @pytest.mark.parametrize(
     "text, expected",
     ((["127.0.0.1", "fe80::1", "2001::2"], ["2001::2", "127.0.0.1", "fe80::1"]),),