Unify page.on event mappings

browser/mapping_test.go

@@ -196,8 +196,7 @@ func TestMappings(t *testing.T) {
 		"mapMetricEvent": {
 			apiInterface: (*metricEventAPI)(nil),
 			mapp: func() mapping {
-				m, _ := mapMetricEvent(moduleVU{VU: vu}, &common.MetricEvent{})
-				return m
+				return mapMetricEvent(moduleVU{VU: vu}, &common.MetricEvent{})
 			},
 		},
 		"mapTouchscreen": {

browser/metric_event_mapping.go

@@ -7,23 +7,9 @@ import (
 )
 
 // mapMetricEvent to the JS module.
-func mapMetricEvent(vu moduleVU, cm *common.MetricEvent) (mapping, error) {
+func mapMetricEvent(vu moduleVU, cm *common.MetricEvent) mapping {
 	rt := vu.VU.Runtime()
 
-	// We're setting up the function in the Sobek context that will be reused
-	// for this VU.
-	_, err := rt.RunString(`
-	function _k6BrowserCheckRegEx(pattern, url) {
-		let r = pattern;
-		if (typeof pattern === 'string') {
-			r = new RegExp(pattern);
-		}
-		return r.test(url);
-	}`)
-	if err != nil {
-		return nil, fmt.Errorf("evaluating regex function: %w", err)
-	}
-
 	return mapping{
 		"tag": func(urls common.URLTagPatterns) error {
 			callback := func(pattern, url string) (bool, error) {
@@ -39,5 +25,5 @@ func mapMetricEvent(vu moduleVU, cm *common.MetricEvent) (mapping, error) {
 
 			return cm.Tag(callback, urls)
 		},
-	}, nil
+	}
 }

browser/page_mapping.go

@@ -243,14 +243,11 @@ func mapPage(vu moduleVU, p *common.Page) mapping { //nolint:gocognit,cyclop
 							return errors.New("incorrect metric message")
 						}
 
-						mapping, err := mapMetricEvent(vu, m)
-						if err != nil {
-							return fmt.Errorf("mapping the metric: %w", err)
-						}
-
-						if _, err = handler(sobek.Undefined(), vu.VU.Runtime().ToValue(mapping)); err != nil {
+						mapping := mapMetricEvent(vu, m)
+						if _, err := handler(sobek.Undefined(), vu.VU.Runtime().ToValue(mapping)); err != nil {
 							return fmt.Errorf("executing page.on('metric') handler: %w", err)
 						}
+
 						return nil
 					})
 					<-c
@@ -259,6 +256,25 @@ func mapPage(vu moduleVU, p *common.Page) mapping { //nolint:gocognit,cyclop
 				return fmt.Errorf("unknown page event: %q", event)
 			}
 
+			if event == common.EventPageMetricCalled {
+				// Register a custom regex function for the metric event
+				// that will be used to check URLs against the patterns.
+				// This is needed because we want to use the JavaScript regex
+				// to comply with what users expect when using the `tag` method.
+				_, err := rt.RunString(`
+					function _k6BrowserCheckRegEx(pattern, url) {
+						let r = pattern;
+						if (typeof pattern === 'string') {
+							r = new RegExp(pattern);
+						}
+						return r.test(url);
+					}
+				`)
+				if err != nil {
+					return fmt.Errorf("evaluating regex function: %w", err)
+				}
+			}
+
 			return p.On(event, runInTaskQueue) //nolint:wrapcheck
 		},
 		"opener": func() *sobek.Promise {