Add requireFail. Like fail(), but it also always throws an error

Sources/Nimble/DSL+Require.swift

@@ -289,3 +289,17 @@ public func unwrapa<T>(fileID: String = #fileID, file: FileString = #filePath, l
 public func unwrapa<T>(fileID: String = #fileID, file: FileString = #filePath, line: UInt = #line, column: UInt = #column, customError: Error? = nil, description: String? = nil, _ expression: @autoclosure () -> (() async throws -> T?)) async throws -> T {
     try await requirea(fileID: fileID, file: file, line: line, column: column, customError: customError, expression()).toNot(beNil(), description: description)
 }
+
+/// Always fails the test and throw an error to prevent further test execution.
+///
+/// - Parameter message: A custom message to use in place of the default one.
+/// - Parameter customError: A custom error to throw in place of a ``RequireError``.
+public func requireFail(_ message: String? = nil, customError: Error? = nil, fileID: String = #fileID, filePath: FileString = #filePath, line: UInt = #line, column: UInt = #column) throws {
+    let location = SourceLocation(fileID: fileID, filePath: filePath, line: line, column: column)
+    let handler = NimbleEnvironment.activeInstance.assertionHandler
+
+    let msg = message ?? "requireFail() always fails"
+    handler.assert(false, message: FailureMessage(stringValue: msg), location: location)
+
+    throw customError ?? RequireError(message: msg, location: location)
+}

Tests/NimbleTests/DSLTest.swift

@@ -219,4 +219,32 @@ final class DSLTest: XCTestCase {
             try await unwrapa(description: "Other Message", await asyncOptional(nil))
         }
     }
+
+    func testRequireFail() throws {
+        struct MyCustomError: Error {}
+
+        failsWithErrorMessage("requireFail() always fails") {
+            do {
+                try requireFail()
+            } catch {
+                expect(error as? RequireError).toNot(beNil())
+            }
+        }
+
+        failsWithErrorMessage("Custom error message") {
+            do {
+                try requireFail("Custom error message")
+            } catch {
+                expect(error as? RequireError).toNot(beNil())
+            }
+        }
+
+        failsWithErrorMessage("Custom message with custom error") {
+            do {
+                try requireFail("Custom message with custom error", customError: MyCustomError())
+            } catch {
+                expect(error as? MyCustomError).toNot(beNil())
+            }
+        }
+    }
 }