test(e2e): only run "Update Style" when query parameters are set (#2693)

Previously, the page always created an `StyleUpdate` object even when no
related query parameters was set. So the "Update Style" API was always
called.
The object is now only created when query parameters are present. It
lets test the rendering when the API is not called (which is the general
use case).

Author: tbouffard

dev/ts/main.ts

@@ -239,15 +239,21 @@ function configureStyleFromParameters(parameters: URLSearchParams): void {
   }
 
   // Collect style properties to update them later with the bpmn-visualization API
-  // The implementation will be generalized when more properties will be supported (in particular, the query parameter name)
-  // For example, we could extract all query params starting with style.api, then rebuild the StyleUpdate from the extracted params
-  style = { stroke: {}, font: {}, fill: {} };
-
-  parameters.get('style.api.stroke.color') && (style.stroke.color = parameters.get('style.api.stroke.color'));
-  parameters.get('style.api.font.color') && (style.font.color = parameters.get('style.api.font.color'));
-  parameters.get('style.api.font.opacity') && (style.font.opacity = Number(parameters.get('style.api.font.opacity')));
-  parameters.get('style.api.fill.color') && (style.fill.color = parameters.get('style.api.fill.color'));
-  parameters.get('style.api.fill.opacity') && (style.fill.opacity = Number(parameters.get('style.api.fill.opacity')));
+  logStartup(`Configuring the "Update Style" API from query parameters`);
+  // Only create the StyleUpdate object if some parameters are set
+  if (Array.from(parameters.keys()).filter(key => key.startsWith('style.api.')).length > 0) {
+    style = { stroke: {}, font: {}, fill: {} };
+
+    parameters.get('style.api.stroke.color') && (style.stroke.color = parameters.get('style.api.stroke.color'));
+    parameters.get('style.api.font.color') && (style.font.color = parameters.get('style.api.font.color'));
+    parameters.get('style.api.font.opacity') && (style.font.opacity = Number(parameters.get('style.api.font.opacity')));
+    parameters.get('style.api.fill.color') && (style.fill.color = parameters.get('style.api.fill.color'));
+    parameters.get('style.api.fill.opacity') && (style.fill.opacity = Number(parameters.get('style.api.fill.opacity')));
+
+    logStartup(`Prepared "Update Style" API object`, style);
+  } else {
+    logStartup(`No query parameters, do not set the "Update Style" API object`);
+  }
 }
 
 function configureBpmnElementIdToCollapseFromParameters(parameters: URLSearchParams): void {