[SwiftRefactor] Replace custom XCTAssertThrows with XCTAssertThrowsError

Removes `XCTAssertThrows` in favor of XCTest standard way of
testing throwing functions.

Author: xedin

Sources/SwiftRefactor/PackageManifest/ManifestEditError.swift

@@ -14,11 +14,11 @@ import SwiftSyntax
 
 /// An error describing problems that can occur when attempting to edit a
 /// package manifest programattically.
-public enum ManifestEditError: Error {
+public enum ManifestEditError: Error, Equatable {
   case cannotFindPackage
   case cannotFindTargets
   case cannotFindTarget(targetName: String)
-  case cannotFindArrayLiteralArgument(argumentName: String, node: Syntax)
+  case cannotFindArrayLiteralArgument(argumentName: String)
 }
 
 extension ManifestEditError: CustomStringConvertible {
@@ -30,7 +30,7 @@ extension ManifestEditError: CustomStringConvertible {
       return "unable to find package targets in manifest"
     case .cannotFindTarget(targetName: let name):
       return "unable to find target named '\(name)' in package"
-    case .cannotFindArrayLiteralArgument(argumentName: let name, node: _):
+    case .cannotFindArrayLiteralArgument(argumentName: let name):
       return "unable to find array literal for '\(name)' argument"
     }
   }

Sources/SwiftRefactor/PackageManifest/SyntaxEditUtils.swift

@@ -468,8 +468,7 @@ extension FunctionCallExprSyntax {
     if let arg = findArgument(labeled: label) {
       guard let argArray = arg.expression.findArrayArgument() else {
         throw ManifestEditError.cannotFindArrayLiteralArgument(
-          argumentName: label,
-          node: Syntax(arg.expression)
+          argumentName: label
         )
       }
 

Tests/SwiftRefactorTest/ManifestEditTests.swift

@@ -244,7 +244,7 @@ final class ManifestEditTests: XCTestCase {
   }
 
   func testAddPackageDependencyErrors() {
-    XCTAssertThrows(
+    XCTAssertThrowsError(
       try AddPackageDependency.manifestRefactor(
         syntax: """
           // swift-tools-version: 5.5
@@ -254,15 +254,14 @@ final class ManifestEditTests: XCTestCase {
           """,
         in: .init(dependency: Self.swiftSystemPackageDependency)
       )
-    ) { (error: ManifestEditError) in
-      if case .cannotFindPackage = error {
-        return true
-      } else {
-        return false
-      }
+    ) { error in
+      XCTAssertEqual(
+        error as? ManifestEditError,
+        .cannotFindPackage
+      )
     }
 
-    XCTAssertThrows(
+    XCTAssertThrowsError(
       try AddPackageDependency.manifestRefactor(
         syntax: """
           // swift-tools-version: 5.5
@@ -273,12 +272,11 @@ final class ManifestEditTests: XCTestCase {
           """,
         in: .init(dependency: Self.swiftSystemPackageDependency)
       )
-    ) { (error: ManifestEditError) in
-      if case .cannotFindArrayLiteralArgument(argumentName: "dependencies", node: _) = error {
-        return true
-      } else {
-        return false
-      }
+    ) { (error: any Error) in
+      XCTAssertEqual(
+        error as? ManifestEditError,
+        .cannotFindArrayLiteralArgument(argumentName: "dependencies")
+      )
     }
   }
 
@@ -710,19 +708,3 @@ func assertManifestRefactor(
     "didn't get all of the auxiliary files we expected"
   )
 }
-
-func XCTAssertThrows<T: Swift.Error, Ignore>(
-  _ expression: @autoclosure () throws -> Ignore,
-  file: StaticString = #filePath,
-  line: UInt = #line,
-  _ errorHandler: (T) -> Bool
-) {
-  do {
-    let result = try expression()
-    XCTFail("body completed successfully: \(result)", file: file, line: line)
-  } catch let error as T {
-    XCTAssertTrue(errorHandler(error), "Error handler returned false", file: file, line: line)
-  } catch {
-    XCTFail("unexpected error thrown: \(error)", file: file, line: line)
-  }
-}