Improve assertions on async throwing expressions

.swiftformat

@@ -11,4 +11,5 @@
 
 # rules
 
---disable preferForLoop,hoistAwait
+--disable preferForLoop
+

Sources/SwiftPolyglotCore/SwiftPolyglotError.swift

@@ -5,6 +5,8 @@ enum SwiftPolyglotError: Error {
     case unsupportedVariation(variation: String)
 }
 
+extension SwiftPolyglotError: Equatable {}
+
 extension SwiftPolyglotError: LocalizedError {
     public var errorDescription: String? {
         switch self {

Tests/SwiftPolyglotCoreTests/SwiftPolyglotCoreTests.swift

@@ -21,7 +21,7 @@ final class SwiftPolyglotCoreTests: XCTestCase {
             isRunningInAGitHubAction: false
         )
 
-        await XCTAssertNoThrowAsync(try await swiftPolyglotCore.run())
+        await XCTAssertNoThrowAsync(swiftPolyglotCore.run)
     }
 
     func testStringCatalogVariationsFullyTranslated() async throws {
@@ -43,7 +43,7 @@ final class SwiftPolyglotCoreTests: XCTestCase {
             isRunningInAGitHubAction: false
         )
 
-        await XCTAssertNoThrowAsync(try await swiftPolyglotCore.run())
+        await XCTAssertNoThrowAsync(swiftPolyglotCore.run)
     }
 
     func testStringCatalogWithMissingTranslations() async throws {
@@ -65,7 +65,7 @@ final class SwiftPolyglotCoreTests: XCTestCase {
             isRunningInAGitHubAction: false
         )
 
-        await XCTAssertThrowsErrorAsync(try await swiftPolyglotCore.run())
+        await XCTAssertThrowsErrorAsync(swiftPolyglotCore.run, SwiftPolyglotError.missingTranslations)
     }
 
     func testStringCatalogWithMissingVariations() async throws {
@@ -87,6 +87,6 @@ final class SwiftPolyglotCoreTests: XCTestCase {
             isRunningInAGitHubAction: false
         )
 
-        await XCTAssertThrowsErrorAsync(try await swiftPolyglotCore.run())
+        await XCTAssertThrowsErrorAsync(swiftPolyglotCore.run, SwiftPolyglotError.missingTranslations)
     }
 }

Tests/SwiftPolyglotCoreTests/XCTest+AsyncThrowingExpression.swift

@@ -5,33 +5,23 @@ import XCTest
 ///
 /// Example usage:
 ///
-///     await assertNoThrowAsync(
-///         try await sut.function()
-///     ) { error in
-///         XCTAssertEqual(error as? MyError, MyError.specificError)
-///     }
+///     await assertNoThrowAsync(sut.function)
 ///
 /// - Parameters:
 ///   - expression: An asynchronous expression that can throw an error.
-///   - message: An optional description of a failure.
+///   - failureMessage: An optional description of a failure.
 ///   - file: The file where the failure occurs. The default is the file path of the test case where this function is being called.
 ///   - line: The line number where the failure occurs. The default is the line number where this function is being called.
 public func XCTAssertNoThrowAsync(
-    _ expression: @autoclosure () async throws -> some Any,
-    _ message: @autoclosure () -> String = "",
+    _ expression: () async throws -> some Any,
+    failureMessage: String = "Asynchronous call did throw an error.",
     file: StaticString = #filePath,
     line: UInt = #line
 ) async {
     do {
         _ = try await expression()
     } catch {
-        // expected no error to be thrown, but it was
-        let customMessage = message()
-        if customMessage.isEmpty {
-            XCTFail("Asynchronous call did throw an error.", file: file, line: line)
-        } else {
-            XCTFail(customMessage, file: file, line: line)
-        }
+        XCTFail(failureMessage, file: file, line: line)
     }
 }
 
@@ -40,37 +30,33 @@ public func XCTAssertNoThrowAsync(
 ///
 /// Example usage:
 ///
-///     await assertThrowsAsyncError(
-///         try await sut.function()
-///     ) { error in
-///         XCTAssertEqual(error as? MyError, MyError.specificError)
-///     }
+///     await assertThrowsAsyncError(sut.function, MyError.specificError)
 ///
 /// - Parameters:
 ///   - expression: An asynchronous expression that can throw an error.
-///   - message: An optional description of a failure.
+///   - errorThrown: The error type that should be thrown.
+///   - failureMessage: An optional description of a failure.
 ///   - file: The file where the failure occurs. The default is the file path of the test case where this function is being called.
 ///   - line: The line number where the failure occurs. The default is the line number where this function is being called.
-///   - errorHandler: An optional handler for errors that `expression` throws.
 ///
-/// from: https://gitlab.com/-/snippets/2567566
-public func XCTAssertThrowsErrorAsync(
-    _ expression: @autoclosure () async throws -> some Any,
-    _ message: @autoclosure () -> String = "",
+/// from: https://arturgruchala.com/testing-async-await-exceptions/
+func XCTAssertThrowsErrorAsync<E>(
+    _ expression: () async throws -> some Any,
+    _ errorThrown: E,
+    failureMessage: String = "Asynchronous call did not throw an error.",
     file: StaticString = #filePath,
-    line: UInt = #line,
-    _ errorHandler: (_ error: any Error) -> Void = { _ in }
-) async {
+    line: UInt = #line
+) async where E: Equatable, E: Error {
     do {
         _ = try await expression()
-        // expected error to be thrown, but it was not
-        let customMessage = message()
-        if customMessage.isEmpty {
-            XCTFail("Asynchronous call did not throw an error.", file: file, line: line)
-        } else {
-            XCTFail(customMessage, file: file, line: line)
-        }
+        XCTFail(failureMessage, file: file, line: line)
     } catch {
-        errorHandler(error)
+        XCTAssertEqual(
+            error as? E,
+            errorThrown,
+            "Asynchronous call did not throw the given error \"\(errorThrown)\".",
+            file: file,
+            line: line
+        )
     }
 }