From f015ebb7dd8763c864fc1a94141725071ebe064c Mon Sep 17 00:00:00 2001
From: Anthony Drendel <me@anthonydrendel.com>
Date: Wed, 29 Apr 2026 23:04:50 +0200
Subject: [PATCH 1/2] Set default nanosecond tolerance to zero

---
 Sources/DispatchTimer/DispatchTimer.swift     |  9 ++++-
 .../DispatchTimerTests.swift                  | 38 +++++++++++++++++++
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/Sources/DispatchTimer/DispatchTimer.swift b/Sources/DispatchTimer/DispatchTimer.swift
index 301edd0..c19779e 100644
--- a/Sources/DispatchTimer/DispatchTimer.swift
+++ b/Sources/DispatchTimer/DispatchTimer.swift
@@ -73,7 +73,7 @@ public final class DispatchTimer: Sendable {
     }
 }
 
-private extension DispatchTimer {
+extension DispatchTimer {
     static func defaultTolerance(_ interval: DispatchTimeInterval) -> DispatchTimeInterval {
         switch interval {
         case let .seconds(amount):
@@ -85,13 +85,18 @@ private extension DispatchTimer {
         case let .microseconds(amount):
             guard amount > 0 else { return .never }
             return .nanoseconds(oneTenthOfOneThousand(of: amount))
-        case .nanoseconds, .never:
+        case let .nanoseconds(amount):
+            guard amount > 0 else { return .never }
+            return .nanoseconds(0)
+        case .never:
             return .never
         @unknown default:
             return .never
         }
     }
+}
 
+private extension DispatchTimer {
     func fire() {
         block()
         if !isRepeating { source.cancel() }
diff --git a/Tests/DispatchTimerTests/DispatchTimerTests.swift b/Tests/DispatchTimerTests/DispatchTimerTests.swift
index de37977..3384577 100644
--- a/Tests/DispatchTimerTests/DispatchTimerTests.swift
+++ b/Tests/DispatchTimerTests/DispatchTimerTests.swift
@@ -55,11 +55,49 @@ final class DispatchTimerTests: XCTestCase {
         timer.invalidate()
     }
 
+    func testDefaultToleranceForPositiveNanosecondsIsZero() throws {
+        XCTAssertEqual(
+            DispatchTimer.defaultTolerance(.nanoseconds(1)),
+            .nanoseconds(0)
+        )
+        XCTAssertEqual(
+            DispatchTimer.defaultTolerance(.nanoseconds(50_000_000)),
+            .nanoseconds(0)
+        )
+    }
+
+    func testDefaultToleranceForNonPositiveNanosecondsIsNever() throws {
+        XCTAssertEqual(
+            DispatchTimer.defaultTolerance(.nanoseconds(0)),
+            .never
+        )
+        XCTAssertEqual(
+            DispatchTimer.defaultTolerance(.nanoseconds(-1)),
+            .never
+        )
+    }
+
+    func testDefaultToleranceForNeverIsNever() throws {
+        XCTAssertEqual(
+            DispatchTimer.defaultTolerance(.never),
+            .never
+        )
+    }
+
     static var allTests = [
         ("testNonRepeatingTimer", testNonRepeatingTimer),
         ("testRepeatingTimer", testRepeatingTimer),
         ("testFireAtTimer", testFireAtTimer),
         ("testInvalidateCancelsTimer", testInvalidateCancelsTimer),
         ("testFireAtInPastFiresImmediately", testFireAtInPastFiresImmediately),
+        (
+            "testDefaultToleranceForPositiveNanosecondsIsZero",
+            testDefaultToleranceForPositiveNanosecondsIsZero
+        ),
+        (
+            "testDefaultToleranceForNonPositiveNanosecondsIsNever",
+            testDefaultToleranceForNonPositiveNanosecondsIsNever
+        ),
+        ("testDefaultToleranceForNeverIsNever", testDefaultToleranceForNeverIsNever),
     ]
 }

From 355a373ee1ec26d0ce55f6847ef4774a819f03ca Mon Sep 17 00:00:00 2001
From: Anthony Drendel <me@anthonydrendel.com>
Date: Wed, 29 Apr 2026 23:10:16 +0200
Subject: [PATCH 2/2] Update GitHub Actions workflow

---
 .github/workflows/ci.yml | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9e1184b..ee10ff3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -4,11 +4,11 @@ on: push
 
 jobs:
   test:
-    runs-on: macos-12
+    runs-on: macos-15
     
     steps:
-      - uses: actions/checkout@v3
-      - name: Select Xcode 14
-        run: sudo xcode-select -s /Applications/Xcode_14.1.app
+      - uses: actions/checkout@v4
+      - name: Select Xcode 26
+        run: sudo xcode-select -s /Applications/Xcode_26.3.app
       - name: Test
         run: swift test