added collection assertions, improved result assertions

Sources/XCTestExtensions/XCTAssert+Collections.swift

@@ -0,0 +1,12 @@
+//
+//  File.swift
+//  
+//
+//  Created by Sam Developer on 19/01/2021.
+//
+
+import XCTest
+
+public func XCTAssertEmpty<C>(_ collection: C, file: StaticString = #file, line: UInt = #line) where C: Collection {
+    XCTAssertEqual(collection.count, 0, file: file, line: line)
+}

Sources/XCTestExtensions/XCTAssert+Result.swift

@@ -6,6 +6,32 @@
 #if !os(watchOS)
 import XCTest
 
+/// Assert that a result is a failure.
+/// - Parameter result: The result to check.
+/// - Parameter message: A message to print if the assertion fails.
+/// - Parameter expectation: An expectation to fullfill if the assertion fails, or if it succeeds with no continuation provided.
+/// - Parameter continuation: A continuation method to call if the assertion succeeded.
+///
+/// In an asynchronous setting, you're typically waiting for an expectation to be fullfilled before ending the test.
+/// If this assertion failed, you may want to exit the tests early, which is why we accept an expectation to fullfill.
+/// Conversely if the assertion succeeds, you may want to perform extra work, which is why we accept a continuation block.
+/// If no continuation is provided, but an expectation was provided, we call the expectation if the assertion succeeds, on the
+/// assumption that there's nothing more to do and we want to signal that the test is done.
+
+public func XCTAssertFailure<S,F>(_ result: Result<S,F>, message: String = "Unexpected Success", expectation: XCTestExpectation? = nil, continuation: ((F) -> Void)? = nil) {
+    switch result {
+    case .success(let success):
+        XCTFail("\(message): \(success)")
+        expectation?.fulfill()
+    case .failure(let error):
+        if let continuation = continuation {
+            continuation(error)
+        } else {
+            expectation?.fulfill()
+        }
+    }
+}
+
 /// Assert that a result is a success.
 /// - Parameter result: The result to check.
 /// - Parameter message: A message to print if the assertion fails.
@@ -32,6 +58,7 @@ public func XCTAssertSuccess<S,F>(_ result: Result<S,F>, message: String = "Fail
     }
 }
 
+
 #if os(macOS) || os(Linux)
 /// Assert that the result of running an external executable matches expected values.
 public func XCTAssertResult(_ result: XCTestRunner.Result, status: Int32, stdout: String, stderr: String, ignoringWhitespace: Bool = true, file: StaticString = #file, line: UInt = #line) {