bug for bug compat

tests/integration/fixtures/object_id_no_friendly_name_no_mac_suffix.yaml

@@ -0,0 +1,25 @@
+esphome:
+  name: test-device
+  # No friendly_name set, no MAC suffix
+  # OLD behavior: object_id = device name because Python pre-computed with fallback
+
+host:
+
+api:
+
+logger:
+
+sensor:
+  # Empty name entity - OLD behavior used device name as fallback
+  - platform: template
+    name: ""
+    id: sensor_empty_name
+    lambda: return 42.0;
+    update_interval: 60s
+
+  # Named entity for comparison
+  - platform: template
+    name: "Temperature"
+    id: sensor_named
+    lambda: return 43.0;
+    update_interval: 60s

tests/integration/fixtures/object_id_no_friendly_name_with_mac_suffix.yaml

@@ -0,0 +1,26 @@
+esphome:
+  name: test-device
+  # No friendly_name set, MAC suffix enabled
+  # OLD behavior: object_id = "" (empty) because is_object_id_dynamic_() used App.get_friendly_name() directly
+  name_add_mac_suffix: true
+
+host:
+
+api:
+
+logger:
+
+sensor:
+  # Empty name entity - OLD behavior produced empty object_id when MAC suffix enabled
+  - platform: template
+    name: ""
+    id: sensor_empty_name
+    lambda: return 42.0;
+    update_interval: 60s
+
+  # Named entity for comparison
+  - platform: template
+    name: "Temperature"
+    id: sensor_named
+    lambda: return 43.0;
+    update_interval: 60s

tests/integration/test_object_id_no_friendly_name.py

@@ -0,0 +1,138 @@
+"""Integration tests for object_id when friendly_name is not set.
+
+These tests verify bug-for-bug compatibility with the old behavior:
+
+1. With MAC suffix enabled + no friendly_name:
+   - OLD: is_object_id_dynamic_() was true, used App.get_friendly_name() directly
+   - OLD: object_id = "" (empty) because friendly_name was empty
+   - NEW: Must maintain same behavior for compatibility
+
+2. Without MAC suffix + no friendly_name:
+   - OLD: is_object_id_dynamic_() was false, used pre-computed object_id_c_str_
+   - OLD: Python computed object_id with fallback to device name
+   - NEW: Must maintain same behavior (object_id = device name)
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from esphome.helpers import fnv1_hash_object_id, sanitize, snake_case
+
+from .types import APIClientConnectedFactory, RunCompiledFunction
+
+# Host platform default MAC: 98:35:69:ab:f6:79 -> suffix "abf679"
+MAC_SUFFIX = "abf679"
+
+# FNV1 offset basis - hash of empty string
+FNV1_OFFSET_BASIS = 2166136261
+
+
+def compute_expected_object_id(name: str) -> str:
+    """Compute expected object_id from name using Python helpers."""
+    return sanitize(snake_case(name))
+
+
+@pytest.mark.asyncio
+async def test_object_id_no_friendly_name_with_mac_suffix(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test object_id when friendly_name not set but MAC suffix enabled.
+
+    OLD behavior (bug-for-bug compatibility):
+    - is_object_id_dynamic_() returned true (no own name AND mac suffix enabled)
+    - format_dynamic_object_id() used App.get_friendly_name() directly
+    - Since friendly_name was empty, object_id was empty
+
+    This was arguably a bug, but we maintain it for compatibility.
+    """
+    async with run_compiled(yaml_config), api_client_connected() as client:
+        device_info = await client.device_info()
+        assert device_info is not None
+
+        # Device name should include MAC suffix
+        expected_device_name = f"test-device-{MAC_SUFFIX}"
+        assert device_info.name == expected_device_name
+
+        # Friendly name should be empty (not set in config)
+        assert device_info.friendly_name == ""
+
+        entities, _ = await client.list_entities_services()
+
+        # Find the empty-name entity
+        empty_name_entities = [e for e in entities if e.name == ""]
+        assert len(empty_name_entities) == 1
+
+        entity = empty_name_entities[0]
+
+        # OLD behavior: object_id was empty because App.get_friendly_name() was empty
+        # This is bug-for-bug compatibility
+        assert entity.object_id == "", (
+            f"Expected empty object_id for bug-for-bug compatibility, "
+            f"got '{entity.object_id}'"
+        )
+
+        # Hash should be FNV1_OFFSET_BASIS (hash of empty string)
+        assert entity.key == FNV1_OFFSET_BASIS, (
+            f"Expected hash of empty string ({FNV1_OFFSET_BASIS:#x}), "
+            f"got {entity.key:#x}"
+        )
+
+        # Named entity should work normally
+        named_entities = [e for e in entities if e.name == "Temperature"]
+        assert len(named_entities) == 1
+        assert named_entities[0].object_id == "temperature"
+
+
+@pytest.mark.asyncio
+async def test_object_id_no_friendly_name_no_mac_suffix(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test object_id when friendly_name not set and no MAC suffix.
+
+    OLD behavior:
+    - is_object_id_dynamic_() returned false (mac suffix not enabled)
+    - Used object_id_c_str_ which was pre-computed in Python
+    - Python used get_base_entity_object_id() with fallback to CORE.name
+
+    Result: object_id = sanitize(snake_case(device_name))
+    """
+    async with run_compiled(yaml_config), api_client_connected() as client:
+        device_info = await client.device_info()
+        assert device_info is not None
+
+        # Device name should NOT include MAC suffix
+        assert device_info.name == "test-device"
+
+        # Friendly name should be empty (not set in config)
+        assert device_info.friendly_name == ""
+
+        entities, _ = await client.list_entities_services()
+
+        # Find the empty-name entity
+        empty_name_entities = [e for e in entities if e.name == ""]
+        assert len(empty_name_entities) == 1
+
+        entity = empty_name_entities[0]
+
+        # OLD behavior: object_id was computed from device name
+        expected_object_id = compute_expected_object_id("test-device")
+        assert entity.object_id == expected_object_id, (
+            f"Expected object_id '{expected_object_id}' from device name, "
+            f"got '{entity.object_id}'"
+        )
+
+        # Hash should match device name
+        expected_hash = fnv1_hash_object_id("test-device")
+        assert entity.key == expected_hash, (
+            f"Expected hash {expected_hash:#x}, got {entity.key:#x}"
+        )
+
+        # Named entity should work normally
+        named_entities = [e for e in entities if e.name == "Temperature"]
+        assert len(named_entities) == 1
+        assert named_entities[0].object_id == "temperature"