Add TestingSupport module

Author: erikbasargin

.gitignore

@@ -6,3 +6,4 @@ DerivedData/
 .swiftpm/configuration/registries.json
 .swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
 .netrc
+Package.resolved

Package.swift

@@ -11,13 +11,26 @@ let package = Package(
             targets: ["AsyncSwiftly"]
         ),
     ],
+    dependencies: [
+        .package(url: "https://github.com/apple/swift-async-algorithms.git", from: "1.0.4"),
+    ],
     targets: [
         .target(
             name: "AsyncSwiftly"
         ),
+        .target(
+            name: "TestingSupport",
+            dependencies: [
+                .product(name: "AsyncAlgorithms", package: "swift-async-algorithms"),
+            ],
+        ),
         .testTarget(
             name: "AsyncSwiftlyTests",
             dependencies: ["AsyncSwiftly"]
         ),
+        .testTarget(
+            name: "TestingSupportTests",
+            dependencies: ["TestingSupport"]
+        ),
     ]
 )

Sources/TestingSupport/AsyncSequence+Collect.swift

@@ -0,0 +1,11 @@
+import AsyncAlgorithms
+import Foundation
+
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
+extension AsyncSequence {
+    
+    /// Returns the array of the elements of the asynchronous sequence.
+    @inlinable package func collect() async rethrows -> [Element] {
+        try await reduce(into: []) { $0.append($1) }
+    }
+}

Sources/TestingSupport/TestError.swift

@@ -0,0 +1,10 @@
+import Foundation
+
+package struct TestError: LocalizedError, Equatable {
+    
+    package var errorDescription: String? { 
+        "TestError" 
+    }
+    
+    package init() {}
+}

Tests/TestingSupportTests/AsyncSequence+CollectTests.swift

@@ -0,0 +1,32 @@
+import Testing
+import TestingSupport
+
+struct AsyncSequenceCollectTests {
+
+    @Test(arguments: [
+        [],
+        [1],
+        [1, 2, 3]
+    ])
+    func collect_produces_array_of_elements_of_source_sequence(source: [Int]) async throws {
+        let sequence = source.async
+        let expectedResult = Array(source)
+
+        await #expect(sequence.collect() == expectedResult)
+    }
+
+    @Test func collect_produces_empty_array_when_source_sequence_is_completed_without_elements() async throws {
+        let stream = AsyncStream<Int> { $0.finish() }
+        await #expect(stream.collect().isEmpty == true)
+    }
+
+    @Test func collect_rethrows_error_when_source_sequence_is_failed() async throws {
+        let stream = AsyncThrowingStream {
+            throw TestError()
+        }
+
+        await #expect(throws: TestError.self) {
+            _ = try await stream.collect()
+        }
+    }
+}