Effect.cancel(ids:) prefer sequence of ids over variadic list. (#1009)

* Disfavor variadic cancellation

* Changed ids paramter from array to sequence

* Small typo

Author: iampatbrown

Sources/ComposableArchitecture/Effects/Cancellation.swift

@@ -89,16 +89,17 @@ extension Effect {
   /// - Parameter ids: A variadic list of effect identifiers.
   /// - Returns: A new effect that will cancel any currently in-flight effects with the given
   ///   identifiers.
+  @_disfavoredOverload
   public static func cancel(ids: AnyHashable...) -> Effect {
     .cancel(ids: ids)
   }
 
   /// An effect that will cancel multiple currently in-flight effects with the given identifiers.
   ///
-  /// - Parameter ids: An array of effect identifiers.
+  /// - Parameter ids: A sequence of effect identifiers.
   /// - Returns: A new effect that will cancel any currently in-flight effects with the given
   ///   identifiers.
-  public static func cancel(ids: [AnyHashable]) -> Effect {
+  public static func cancel<S: Sequence>(ids: S) -> Effect where S.Element == AnyHashable {
     .merge(ids.map(Effect.cancel(id:)))
   }
 }

Tests/ComposableArchitectureTests/EffectCancellationTests.swift

@@ -302,4 +302,34 @@ final class EffectCancellationTests: XCTestCase {
 
     XCTAssertEqual(output, [1, 2])
   }
+  
+  func testMultipleCancellations() {
+    let scheduler = DispatchQueue.test
+    var values: [Int] = []
+
+    struct CancellationId: Hashable {
+      var id: Int
+    }
+
+    let effects = [1, 2, 3, 4, 5].map { id in
+      Just(id)
+        .delay(for: 1, scheduler: scheduler)
+        .eraseToEffect()
+        .cancellable(id: CancellationId(id: id))
+    }
+
+    Effect<Int, Never>.merge(effects)
+      .sink { values.append($0) }
+      .store(in: &self.cancellables)
+
+    Effect<Int, Never>.merge(
+      .cancel(ids: CancellationId(id: 1), CancellationId(id: 2)),
+      .cancel(ids: [CancellationId(id: 4), CancellationId(id: 5)][...])
+    )
+      .sink { _ in }
+      .store(in: &self.cancellables)
+
+    scheduler.advance(by: 1)
+    XCTAssertEqual(values, [3])
+  }
 }