Merge 310734d2f8 into 071d1cac3c

Motivation:

* Improve test coverage

Modifications:

Enable macOS CI to be run on pull request commits and make the use of
the nightly runner pool for main.yml jobs explicit.

Result:

Improved test coverage.

.github/workflows/main.yml

@@ -16,3 +16,10 @@ jobs:
       linux_6_0_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
       linux_nightly_next_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
       linux_nightly_main_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+
+  macos-tests:
+    name: macOS tests
+    uses: apple/swift-nio/.github/workflows/macos_tests.yml@main
+    with:
+      runner_pool: nightly
+      build_scheme: swift-metrics-Package

.github/workflows/pull_request.yml

@@ -24,3 +24,10 @@ jobs:
   cxx-interop:
     name: Cxx interop
     uses: apple/swift-nio/.github/workflows/cxx_interop.yml@main
+
+  macos-tests:
+    name: macOS tests
+    uses: apple/swift-nio/.github/workflows/macos_tests.yml@main
+    with:
+      runner_pool: general
+      build_scheme: swift-metrics-Package

Sources/Metrics/Metrics.swift

@@ -16,10 +16,16 @@
 // https://github.com/swiftlang/swift/issues/79285
 
 @_exported import CoreMetrics
-import Foundation
+import Dispatch
 
 @_exported import class CoreMetrics.Timer
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
 extension Timer {
     /// Convenience for measuring duration of a closure.
     ///