Initial release

Tests/KnotchyCoreTests/BackendChainTests.swift

@@ -0,0 +1,66 @@
+import Foundation
+import Testing
+@testable import KnotchyCore
+
+@MainActor
+struct BackendChainTests {
+    @Test func runsJobsOneAtATimeInOrder() async {
+        let chain = BackendChain()
+        var log: [String] = []
+        for name in ["a", "b", "c"] {
+            chain.enqueue {
+                log.append("\(name) begins")
+                await Task.yield()
+                log.append("\(name) ends")
+            }
+        }
+        await chain.waitUntilIdle()
+        #expect(log == ["a begins", "a ends", "b begins", "b ends", "c begins", "c ends"])
+    }
+
+    @Test func waitsForJobsEnqueuedByJobs() async {
+        let chain = BackendChain()
+        var log: [String] = []
+        chain.enqueue {
+            log.append("outer")
+            chain.enqueue {
+                await Task.yield()   // Still running when the outer job's Task finishes.
+                log.append("inner")
+            }
+        }
+        await chain.waitUntilIdle()
+        #expect(log == ["outer", "inner"])
+    }
+
+    @Test func closingSkipsJobsThatHaveNotStarted() async {
+        let chain = BackendChain()
+        var log: [String] = []
+        chain.enqueue {
+            log.append("running")
+            chain.close()
+        }
+        chain.enqueue { log.append("queued") }
+        await chain.waitUntilIdle()
+        chain.enqueue { log.append("after close") }
+        await chain.waitUntilIdle()
+        #expect(log == ["running"])
+    }
+
+    @Test func liveIDsAreASnapshot() {
+        let ids = LiveIDs()
+        ids.insert("knotchy-00000001")
+        ids.insert("knotchy-00000002")
+        ids.remove("knotchy-00000001")
+        #expect(ids.snapshot == ["knotchy-00000002"])
+    }
+
+    @Test nonisolated func liveIDsCanBeUsedFromManyThreadsAtOnce() {
+        let ids = LiveIDs()
+        DispatchQueue.concurrentPerform(iterations: 1000) { i in
+            ids.insert("knotchy-\(i)")
+            _ = ids.snapshot
+            if i.isMultiple(of: 2) { ids.remove("knotchy-\(i)") }
+        }
+        #expect(ids.snapshot.count == 500)
+    }
+}