fix: keep debug map link on current frontend (#414)

Use the current page URL to build the debug viewer link so self-hosted and subpath deployments open their own /debug route instead of resolving elsewhere.

Add regression coverage for root and subpath-hosted frontends.

Closes #243.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: DennisOSRM

bundle.js

@@ -87,8 +87,10 @@ var Control = L.Control.extend({
   _openDebug: function() {
     var position = this._map.getCenter(),
       zoom = this._map.getZoom(),
-      prec = 6;
-    window.open("debug/#" + zoom + "/" + position.lat.toFixed(prec) + "/" + position.lng.toFixed(prec));
+      prec = 6,
+      debugUrl = new URL('debug/', window.location.href);
+    debugUrl.hash = zoom + "/" + position.lat.toFixed(prec) + "/" + position.lng.toFixed(prec);
+    window.open(debugUrl.href);
   },
 
   _openMapillary: function() {

bundle.js.map

@@ -0,0 +1,74 @@
+/**
+ * @jest-environment jsdom
+ */
+
+'use strict';
+
+jest.mock('leaflet', () => {
+  function Control() {}
+
+  Control.extend = function(props) {
+    function Extended() {
+      this.options = Object.assign({}, props.options);
+      if (props.initialize) {
+        props.initialize.apply(this, arguments);
+      }
+    }
+
+    Extended.prototype = Object.assign({}, props);
+    return Extended;
+  };
+
+  return {
+    Control: Control,
+    Mixin: { Events: {} },
+    setOptions: function(target, options) {
+      target.options = Object.assign(target.options || {}, options);
+    }
+  };
+});
+
+describe('tools debug map link', () => {
+  let tools;
+  let control;
+  let openSpy;
+
+  beforeEach(() => {
+    jest.resetModules();
+    tools = require('../src/tools');
+    control = tools.control({}, {}, {});
+    control._map = {
+      getCenter: function() {
+        return { lat: 38.8995, lng: -77.0269 };
+      },
+      getZoom: function() {
+        return 13;
+      }
+    };
+    openSpy = jest.spyOn(window, 'open').mockImplementation(function() {});
+  });
+
+  afterEach(() => {
+    openSpy.mockRestore();
+  });
+
+  test('opens the debug map on the current frontend origin', () => {
+    window.history.replaceState({}, '', '/?z=13');
+
+    control._openDebug();
+
+    expect(openSpy).toHaveBeenCalledWith(
+      'http://localhost/debug/#13/38.899500/-77.026900'
+    );
+  });
+
+  test('preserves a frontend subpath when opening the debug map', () => {
+    window.history.replaceState({}, '', '/osrm-frontend/index.html?z=13');
+
+    control._openDebug();
+
+    expect(openSpy).toHaveBeenCalledWith(
+      'http://localhost/osrm-frontend/debug/#13/38.899500/-77.026900'
+    );
+  });
+});