fix: remove the unreliable Releases panel from the Grafana home dashboard

Fixes #5542

Author: mvanhorn

grafana/dashboards/internal/home.json

@@ -47,7 +47,7 @@
     {
       "gridPos": {
         "h": 20,
-        "w": 16,
+        "w": 18,
         "x": 6,
         "y": 0
       },
@@ -63,22 +63,6 @@
       },
       "pluginVersion": "13.0.1+security-01",
       "type": "text"
-    },
-    {
-      "gridPos": {
-        "h": 20,
-        "w": 2,
-        "x": 22,
-        "y": 0
-      },
-      "id": 3,
-      "options": {
-        "feedUrl": "https://api.cors.lol/?url=https://github.com/teslamate-org/teslamate/tags.atom",
-        "showImage": false
-      },
-      "pluginVersion": "13.0.1+security-01",
-      "title": "Releases",
-      "type": "news"
     }
   ],
   "preload": false,

test/grafana/home_dashboard_test.exs

@@ -0,0 +1,46 @@
+defmodule TeslaMate.Grafana.HomeDashboardTest do
+  use ExUnit.Case, async: true
+
+  @dashboard_path "grafana/dashboards/internal/home.json"
+
+  setup_all do
+    json = File.read!(@dashboard_path)
+
+    {:ok, dashboard: Jason.decode!(json), json: json}
+  end
+
+  test "contains only the dashboard list and image panels", %{dashboard: dashboard, json: json} do
+    assert dashboard["title"] == "Home"
+    assert Enum.map(dashboard["panels"], & &1["type"]) == ["dashlist", "text"]
+    assert get_in(dashboard, ["panels", Access.at(1), "options", "content"]) =~ "background-image"
+
+    refute Enum.any?(dashboard["panels"], &(&1["type"] == "news"))
+    refute json =~ "api.cors.lol"
+  end
+
+  test "panels fill the 24-column grid without gaps, overlaps, or overflow", %{
+    dashboard: dashboard
+  } do
+    final_x =
+      dashboard["panels"]
+      |> Enum.sort_by(& &1["gridPos"]["x"])
+      |> Enum.reduce(0, fn %{"gridPos" => %{"w" => width, "x" => x}}, expected_x ->
+        assert width > 0
+        assert x == expected_x
+        assert x + width <= 24
+
+        x + width
+      end)
+
+    assert final_x == 24
+  end
+
+  test "Dockerfile provisions the shipped dashboard as Grafana's home dashboard" do
+    dockerfile = File.read!("grafana/Dockerfile")
+
+    assert dockerfile =~
+             "GF_DASHBOARDS_DEFAULT_HOME_DASHBOARD_PATH=/dashboards_internal/home.json"
+
+    assert dockerfile =~ "COPY dashboards/internal/*.json /dashboards_internal/"
+  end
+end