Make it easier to see example test output

Author: natecook1000

Sources/ArgumentParserTestHelpers/TestHelpers.swift

@@ -249,10 +249,16 @@ extension XCTest {
 
     let outputData = output.fileHandleForReading.readDataToEndOfFile()
     let outputActual = String(data: outputData, encoding: .utf8)!.trimmingCharacters(in: .whitespacesAndNewlines)
-    
+        
     let errorData = error.fileHandleForReading.readDataToEndOfFile()
     let errorActual = String(data: errorData, encoding: .utf8)!.trimmingCharacters(in: .whitespacesAndNewlines)
 
+    print("COMMAND: \(command)")
+    print("STDOUT:")
+    print(outputActual)
+    print("STDERR:")
+    print(errorActual)
+    
     if let expected = expected {
       AssertEqualStringsIgnoringTrailingWhitespace(expected, errorActual + outputActual, file: file, line: line)
     }