We currently use a Testcontainer-based OpenTelemetry Collector for our observability tests. While this works (there is the occasional test failure due to environmental Docker issues), it does require awkward code to extract the data from the collector (multiple containers started, reading log files, using unofficial/unsupported APIs, etc). We are also unable to run the tests on Windows due to Docker/Podman issues there. An in-memory collector can be implemented that alleviates all of those concerns, giving us a fast, easy-to-use API for testing our supported observability libraries.