Add diagnostics support to Fritz (#65334)

* Add diagnostics support to Fritz

* Temporary remove tests

* coveragerc

.coveragerc

@@ -376,6 +376,7 @@ omit =
     homeassistant/components/fritz/common.py
     homeassistant/components/fritz/const.py
     homeassistant/components/fritz/device_tracker.py
+    homeassistant/components/fritz/diagnostics.py
     homeassistant/components/fritz/sensor.py
     homeassistant/components/fritz/services.py
     homeassistant/components/fritz/switch.py

homeassistant/components/fritz/diagnostics.py

@@ -0,0 +1,35 @@
+"""Diagnostics support for AVM FRITZ!Box."""
+from __future__ import annotations
+
+from homeassistant.components.diagnostics import async_redact_data
+from homeassistant.config_entries import ConfigEntry
+from homeassistant.const import CONF_PASSWORD, CONF_USERNAME
+from homeassistant.core import HomeAssistant
+
+from .common import AvmWrapper
+from .const import DOMAIN
+
+TO_REDACT = {CONF_USERNAME, CONF_PASSWORD}
+
+
+async def async_get_config_entry_diagnostics(
+    hass: HomeAssistant, entry: ConfigEntry
+) -> dict:
+    """Return diagnostics for a config entry."""
+    avm_wrapper: AvmWrapper = hass.data[DOMAIN][entry.entry_id]
+
+    diag_data = {
+        "entry": async_redact_data(entry.as_dict(), TO_REDACT),
+        "device_info": {
+            "model": avm_wrapper.model,
+            "current_firmware": avm_wrapper.current_firmware,
+            "latest_firmware": avm_wrapper.latest_firmware,
+            "update_available": avm_wrapper.update_available,
+            "is_router": avm_wrapper.device_is_router,
+            "mesh_role": avm_wrapper.mesh_role,
+            "last_update success": avm_wrapper.last_update_success,
+            "last_exception": avm_wrapper.last_exception,
+        },
+    }
+
+    return diag_data