title: XCTest, Failed to load test bundle. Crash on test launch
body: <p>In Xcode 9.1, I added a Unit Test Target to an older project and I'm not able to get tests to run. The target crashes on launch with the following error in the console:</p>
  
  <p><strong>The bundle “XXXTests” couldn’t be loaded because it doesn’t contain a version for the current architecture*</strong></p>
  
  <p>Full output:</p>
  
  <p><code>2017-11-15 11:52:40.973 XXX[54962:16511010] Failed to load test bundle from file:///Users/XXX/Library/Developer/Xcode/DerivedData/XXX-gaxtmzjadfkxzsdciqnpmyczgntj/Build/Products/DEV-iphonesimulator/XXX.app/PlugIns/XXXTests.xctest/: Error Domain=NSCocoaErrorDomain Code=3585 "dlopen_preflight(/Users/XXX/Library/Developer/Xcode/DerivedData/XXX-gaxtmzjadfkxzsdciqnpmyczgntj/Build/Products/DEV-iphonesimulator/XXX.app/PlugIns/XXXTests.xctest/XXXTests): no suitable image found.  Did find:
      /Users/XXX/Library/Developer/Xcode/DerivedData/XXX-gaxtmzjadfkxzsdciqnpmyczgntj/Build/Products/DEV-iphonesimulator/XXX.app/PlugIns/XXXTests.xctest/XXXTests: mach-o, but wrong architecture" UserInfo={NSLocalizedRecoverySuggestion=Try installing a universal version of the bundle., NSFilePath=/Users/XXX/Library/Developer/Xcode/DerivedData/XXX-gaxtmzjadfkxzsdciqnpmyczgntj/Build/Products/DEV-iphonesimulator/XXX.app/PlugIns/XXXTests.xctest/XXXTests, NSLocalizedFailureReason=The bundle doesn’t contain a version for the current architecture., NSLocalizedDescription=The bundle “XXXTests” couldn’t be loaded because it doesn’t contain a version for the current architecture., NSDebugDescription=dlopen_preflight(/Users/XXX/Library/Developer/Xcode/DerivedData/XXX-gaxtmzjadfkxzsdciqnpmyczgntj/Build/Products/DEV-iphonesimulator/XXX.app/PlugIns/XXXTests.xctest/XXXTests): no suitable image found.  Did find:
      /Users/XXX/Library/Developer/Xcode/DerivedData/XXX-gaxtmzjadfkxzsdciqnpmyczgntj/Build/Products/DEV-iphonesimulator/XXX.app/PlugIns/XXXTests.xctest/XXXTests: mach-o, but wrong architecture, NSBundlePath=/Users/XXX/Library/Developer/Xcode/DerivedData/XXX-gaxtmzjadfkxzsdciqnpmyczgntj/Build/Products/DEV-iphonesimulator/XXX.app/PlugIns/XXXTests.xctest}
  </code>
  (And then some diagnostic output that I didn't include)</p>
  
  <p>Stuff I've checked after extensively googling:</p>
  
  <ul>
  <li><strong>Build Active Architecture Only</strong> setting is consistent across the app and test targets (With a value of Yes)</li>
  <li><strong>Enable Testability</strong> is set to Yes for the main target</li>
  <li>I've deleted the target and started over, no luck</li>
  </ul>
  
  <p>How do I fix this?</p>