Add capability to load tiled geojsons, eventually as overpass-cache

test/Theme.spec.ts

@@ -0,0 +1,48 @@
+import T from "./TestHelper";
+import {Utils} from "../Utils";
+
+Utils.runningFromConsole = true;
+import TagRenderingQuestion from "../UI/Popup/TagRenderingQuestion";
+import {UIEventSource} from "../Logic/UIEventSource";
+import TagRenderingConfig from "../Customizations/JSON/TagRenderingConfig";
+import LayoutConfig from "../Customizations/JSON/LayoutConfig";
+import {LayoutConfigJson} from "../Customizations/JSON/LayoutConfigJson";
+import * as assert from "assert";
+
+
+new T("Theme tests",
+    [
+        ["Nested overrides work", () => {
+    
+            const themeConfigJson : LayoutConfigJson = {
+                description: "Descr",
+                icon: "",
+                language: ["en"],
+                layers: [
+                    {
+                        builtin: "public_bookcase",
+                        override: {
+                            source:{
+                                geoJson: "xyz"
+                            }
+                        }
+                    }
+                ],
+                maintainer: "",
+                startLat: 0,
+                startLon: 0,
+                startZoom: 0,
+                title: {
+                    en: "Title"
+                },
+                version: "",
+                id: "test"
+            }
+            
+            const themeConfig = new LayoutConfig(themeConfigJson);
+            assert.equal("xyz", themeConfig.layers[0].source.geojsonSource)
+    
+            
+        }]
+    ]
+);