FreshRegistries

A mixin trait to get a fresh empty metric and health check registry every time.

Often a singleton service class defines a gauge with a static name. However, during testing multiple instances are needed. Unfortunately the metrics registry doesn't allow registering a gauge under the same name twice. This is not a problem when a new registry is used for each instance.

The same is the case for health checks (since dropwizard-metrics 4.1).

Example

With the following gauge in class Example:

class Example(db: Database) extends nl.grons.metrics4.scala.DefaultInstrumented {
 // Define a gauge with a static name
 metrics.gauge("aGauge") { db.rowCount() }
}

This trait can be mixed in with any instance of Example:

 val example = new Example(db) with FreshRegistries

See also FreshMetricRegistry and FreshHealthCheckRegistry in case your class only extends InstrumentedBuilder or CheckedBuilder respectively.