Compute shown entity attributes in one place (#29655)

* Compute shown entity attributes in one place

* Remove type assertion

* Unit tests

test/data/entity_attributes.test.ts

@@ -0,0 +1,52 @@
+import type { HassEntity } from "home-assistant-js-websocket";
+import { describe, expect, it } from "vitest";
+
+import { computeShownAttributes } from "../../src/data/entity/entity_attributes";
+
+describe("computeShownAttributes", () => {
+  it("filters globally hidden attributes", () => {
+    const stateObj = {
+      entity_id: "sensor.temperature",
+      attributes: {
+        friendly_name: "Office temperature",
+        unit_of_measurement: "°C",
+        temperature: 21,
+        custom_value: "shown",
+      },
+    } as unknown as HassEntity;
+
+    expect(computeShownAttributes(stateObj)).toEqual([
+      "temperature",
+      "custom_value",
+    ]);
+  });
+
+  it("filters domain and device class specific attributes", () => {
+    const stateObj = {
+      entity_id: "sensor.status",
+      attributes: {
+        device_class: "enum",
+        options: ["home", "away"],
+        current_option: "home",
+      },
+    } as unknown as HassEntity;
+
+    expect(computeShownAttributes(stateObj)).toEqual(["current_option"]);
+  });
+
+  it("keeps device-class attributes for other device classes", () => {
+    const stateObj = {
+      entity_id: "sensor.status",
+      attributes: {
+        device_class: "temperature",
+        options: ["home", "away"],
+        current_option: "home",
+      },
+    } as unknown as HassEntity;
+
+    expect(computeShownAttributes(stateObj)).toEqual([
+      "options",
+      "current_option",
+    ]);
+  });
+});