Introduced booting from fixture url cache in test environment

refs https://github.com/TryGhost/Toolbox/issues/135

- To be able to reliably start ghost instance without a frontend the process needs access to urls/resources caches
- Storing the configuration in "paths" for now as there's no better place for it untill we are able to mock the content folder in pre-boot

core/server/services/url/index.js

@@ -5,8 +5,17 @@ const UrlService = require('./UrlService');
 // NOTE: instead of a path we could give UrlService a "data-resolver" of some sort
 //       so it doesn't have to contain the logic to read data at all. This would be
 //       a possible improvement in the future
-const urlsCachePath = path.join(config.getContentPath('data'), 'urls.json');
-const resourcesCachePath = path.join(config.getContentPath('data'), 'resources.json');
+
+let urlsCachePath = path.join(config.getContentPath('data'), 'urls.json');
+let resourcesCachePath = path.join(config.getContentPath('data'), 'resources.json');
+
+// TODO: remove this hack in favor of loading from the content path when it's possible to do so
+//       by mocking content folders in pre-boot phase
+if (process.env.NODE_ENV.match(/^testing/)){
+    urlsCachePath = path.join(config.get('paths').urlCache, 'urls.json');
+    resourcesCachePath = path.join(config.get('paths').urlCache, 'resources.json');
+}
+
 const urlService = new UrlService({urlsCachePath, resourcesCachePath});
 
 // Singleton

core/shared/config/env/config.testing-mysql.json

@@ -50,5 +50,9 @@
         "useTinfoil": true,
         "useStructuredData": true
     },
-    "useMinFiles": false
+    "useMinFiles": false,
+    "paths": {
+        "fixtures": "test/utils/fixtures/fixtures",
+        "urlCache": "test/utils/fixtures/urls"
+    }
 }

core/shared/config/env/config.testing.json

@@ -51,6 +51,7 @@
     },
     "useMinFiles": false,
     "paths": {
-        "fixtures": "test/utils/fixtures/fixtures"
+        "fixtures": "test/utils/fixtures/fixtures",
+        "urlCache": "test/utils/fixtures/urls"
     }
 }

test/unit/shared/config/loader.test.js

@@ -97,6 +97,7 @@ describe('Config Loader', function () {
                 'contentPath',
                 'fixtures',
                 'assetSrc',
+                'urlCache',
                 'appRoot',
                 'corePath',
                 'clientAssets',