swift-metrics/Sources/MetricsTestKit/Docs.docc/index.md

MetricsTestKit

A set of tools for testing Metrics emitting libraries.

Overview

This module offers a TestMetrics type which can be used to bootstrap the metrics system and then assert metric values on it.

Example

import XCTest
import Metrics
import MetricsTestKit

final class ExampleTests: XCTestCase {
    var metrics: TestMetrics! = TestMetrics()

    override func setUp() {
        MetricsSystem.bootstrapInternal(self.metrics)
    }

    override func tearDown() async throws {
        self.metrics = nil
        MetricsSystem.bootstrapInternal(NOOPMetricsHandler.instance)
    }

    func test_example() async throws {
        // Create a metric using the bootstrapped test metrics backend:
        Recorder(label: "example").record(100)
        
        // extract the `TestRecorder` out of the 
        let recorder = try self.metrics.expectRecorder("example")
        recorder.lastValue?.shouldEqual(6)
    }
}

Topics

Test metrics

• TestCounter
• TestMeter
• TestRecorder
• TestTimer