Copied mongo repo (to patch it)

mongo/internal/testutil/monitor/monitor.go

@@ -0,0 +1,78 @@
+// Copyright (C) MongoDB, Inc. 2022-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+// Package monitor provides test types that are used to monitor client state and actions via the
+// various monitor types supported by the driver.
+package monitor
+
+import (
+	"sync"
+
+	"go.mongodb.org/mongo-driver/event"
+)
+
+// TestPoolMonitor exposes an *event.TestPoolMonitor and collects all events logged to that
+// *event.TestPoolMonitor. It is safe to use from multiple concurrent goroutines.
+type TestPoolMonitor struct {
+	*event.PoolMonitor
+
+	events []*event.PoolEvent
+	mu     sync.RWMutex
+}
+
+func NewTestPoolMonitor() *TestPoolMonitor {
+	tpm := &TestPoolMonitor{
+		events: make([]*event.PoolEvent, 0),
+	}
+	tpm.PoolMonitor = &event.PoolMonitor{
+		Event: func(evt *event.PoolEvent) {
+			tpm.mu.Lock()
+			defer tpm.mu.Unlock()
+			tpm.events = append(tpm.events, evt)
+		},
+	}
+	return tpm
+}
+
+// Events returns a copy of the events collected by the testPoolMonitor. Filters can optionally be
+// applied to the returned events set and are applied using AND logic (i.e. all filters must return
+// true to include the event in the result).
+func (tpm *TestPoolMonitor) Events(filters ...func(*event.PoolEvent) bool) []*event.PoolEvent {
+	tpm.mu.RLock()
+	defer tpm.mu.RUnlock()
+
+	filtered := make([]*event.PoolEvent, 0, len(tpm.events))
+	for _, evt := range tpm.events {
+		keep := true
+		for _, filter := range filters {
+			if !filter(evt) {
+				keep = false
+				break
+			}
+		}
+		if keep {
+			filtered = append(filtered, evt)
+		}
+	}
+
+	return filtered
+}
+
+// ClearEvents will reset the events collected by the testPoolMonitor.
+func (tpm *TestPoolMonitor) ClearEvents() {
+	tpm.mu.Lock()
+	defer tpm.mu.Unlock()
+	tpm.events = tpm.events[:0]
+}
+
+// IsPoolCleared returns true if there are any events of type "event.PoolCleared" in the events
+// recorded by the testPoolMonitor.
+func (tpm *TestPoolMonitor) IsPoolCleared() bool {
+	poolClearedEvents := tpm.Events(func(evt *event.PoolEvent) bool {
+		return evt.Type == event.PoolCleared
+	})
+	return len(poolClearedEvents) > 0
+}