Add Retry.Error.abort to be able to break out of retry block

Author: finestructure

Sources/Retry/Retry.swift

@@ -17,7 +17,8 @@ import Foundation
 
 public enum Retry {
     public enum Error: Swift.Error {
-        case retryLimitExceeded(lastError: Swift.Error?)
+        case abort(with: Swift.Error? = nil)
+        case retryLimitExceeded(lastError: Swift.Error? = nil)
     }
 
     public static func backedOffDelay(baseDelay: Double, attempt: Int) -> UInt32 {
@@ -39,6 +40,8 @@ public enum Retry {
             }
             do {
                 return try block()
+            } catch let Error.abort(with: error) {
+                throw Error.abort(with: error)
             } catch {
                 logger.onError(label: label, error: error)
                 lastError = error
@@ -68,6 +71,8 @@ public enum Retry {
             }
             do {
                 return try await block()
+            } catch let Error.abort(with: error) {
+                throw Error.abort(with: error)
             } catch {
                 logger.onError(label: label, error: error)
                 lastError = error

Tests/RetryTests/RetryTests.swift

@@ -76,6 +76,29 @@ final class RetryTests: XCTestCase {
         XCTAssertEqual(called, 4)
     }
 
+    func test_attempt_abort() throws {
+        var called = 0
+        struct Error: Swift.Error, CustomStringConvertible {
+            var description: String { "test error" }
+        }
+
+        // MUT
+        do {
+            try Retry.attempt("", delay: 0, retries: 3) {
+                called += 1
+                throw Retry.Error.abort(with: Error())
+            }
+            XCTFail("expected an error to be thrown")
+        } catch let Retry.Error.abort(with: .some(error)) {
+            XCTAssertEqual("\(error)", "test error")
+        } catch {
+            XCTFail("unexpected error: \(error)")
+        }
+
+        // validation
+        XCTAssertEqual(called, 1)
+    }
+
     func test_attempt_async() async throws {
         func dummyAsyncFunction() async { }
         var called = 0