M1芯片Mac运行iOS单元测试出现XCTest bundle无效错误

错误表现 #

在M1芯片Mac设备上运行iOS单元测试时，测试套件会直接崩溃，抛出三类bundle相关错误：

• Failed to load test bundle
• No suitable image found
• Trying to load an unsigned library

完整错误日志如下：

2021-11-04 08:53:33.378375-0600 xxx[81944:1274939] Failed to load test bundle from file:///Users/xxx/Library/Developer/XCTestDevices/FDCD6684-3D06-48C9-81E3-DE82C6AB2CCB/data/Containers/Bundle/Application/7143E7F2-E59A-4578-971A-A2A20D42DDB6/xxx.app/PlugIns/Unit%20Tests.xctest/: Error Domain=NSCocoaErrorDomain Code=3587 "dlopen_preflight(/Users/xxx/Library/Developer/XCTestDevices/FDCD6684-3D06-48C9-81E3-DE82C6AB2CCB/data/Containers/Bundle/Application/7143E7F2-E59A-4578-971A-A2A20D42DDB6/xxx.app/PlugIns/Unit Tests.xctest/Unit Tests): no suitable image found.  Did find:
    /Users/xxx/Library/Developer/XCTestDevices/FDCD6684-3D06-48C9-81E3-DE82C6AB2CCB/data/Containers/Bundle/Application/7143E7F2-E59A-4578-971A-A2A20D42DDB6/xxx.app/PlugIns/Unit Tests.xctest/Unit Tests: code signature in (/Users/xxx/Library/Developer/XCTestDevices/FDCD6684-3D06-48C9-81E3-DE82C6AB2CCB/data/Containers/Bundle/Application/7143E7F2-E59A-4578-971A-A2A20D42DDB6/xxx.app/PlugIns/Unit Tests.xctest/Unit Tests) not valid for use in process using Library Validation: Trying to load an unsigned library" UserInfo={NSLocalizedFailureReason=The bundle is damaged or missing necessary resources., NSLocalizedRecoverySuggestion=Try reinstalling the bundle., NSFilePath=/Users/xxx/Library/Developer/XCTestDevices/FDCD6684-3D06-48C9-81E3-DE82C6AB2CCB/data/Containers/Bundle/Application/7143E7F2-E59A-4578-971A-A2A20D42DDB6/xxx.app/PlugIns/Unit Tests.xctest/Unit Tests, NSDebugDescription=dlopen_preflight(/Users/xxx/Library/Developer/XCTestDevices/FDCD6684-3D06-48C9-81E3-DE82C6AB2CCB/data/Containers/Bundle/Application/7143E7F2-E59A-4578-971A-A2A20D42DDB6/xxx.app/PlugIns/Unit Tests.xctest/Unit Tests): no suitable image found.  Did find:
    /Users/xxx/Library/Developer/XCTestDevices/FDCD6684-3D06-48C9-81E3-DE82C6AB2CCB/data/Containers/Bundle/Application/7143E7F2-E59A-4578-971A-A2A20D42DDB6/xxx.app/PlugIns/Unit Tests.xctest/Unit Tests: code signature in (/Users/xxx/Library/Developer/XCTestDevices/FDCD6684-3D06-48C9-81E3-DE82C6AB2CCB/data/Containers/Bundle/Application/7143E7F2-E59A-4578-971A-A2A20D42DDB6/xxx.app/PlugIns/Unit Tests.xctest/Unit Tests) not valid for use in process using Library Validation: Trying to load an unsigned library, NSBundlePath=/Users/xxx/Library/Developer/XCTestDevices/FDCD6684-3D06-48C9-81E3-DE82C6AB2CCB/data/Containers/Bundle/Application/7143E7F2-E59A-4578-971A-A2A20D42DDB6/xxx.app/PlugIns/Unit Tests.xctest, NSLocalizedDescription=The bundle “Unit Tests.xctest” couldn’t be loaded because it is damaged or missing necessary resources.}
2021-11-04 08:53:33.683690-0600 xxx[81944:1274939] The bundle “Unit Tests.xctest” couldn’t be loaded because it is damaged or missing necessary resources. Try reinstalling the bundle.
2021-11-04 08:53:33.683757-0600 xxx[81944:1274939] (dlopen_preflight(/Users/xxx/Library/Developer/XCTestDevices/FDCD6684-3D06-48C9-81E3-DE82C6AB2CCB/data/Containers/Bundle/Application/7143E7F2-E59A-4578-971A-A2A20D42DDB6/xxx.app/PlugIns/Unit Tests.xctest/Unit Tests): no suitable image found.  Did find:
    /Users/xxx/Library/Developer/XCTestDevices/FDCD6684-3D06-48C9-81E3-DE82C6AB2CCB/data/Containers/Bundle/Application/7143E7F2-E59A-4578-971A-A2A20D42DDB6/xxx.app/PlugIns/Unit Tests.xctest/Unit Tests: code signature in (/Users/xxx/Library/Developer/XCTestDevices/FDCD6684-3D06-48C9-81E3-DE82C6AB2CCB/data/Containers/Bundle/Application/7143E7F2-E59A-4578-971A-A2A20D42DDB6/xxx.app/PlugIns/Unit Tests.xctest/Unit Tests) not valid for use in process using Library Validation: Trying to load an unsigned library)

上述相同测试逻辑在Intel芯片Mac设备上可正常运行。

问题原因 #

该错误是M1芯片arm64架构下模拟器独有的签名校验和架构适配问题：

• Intel芯片Mac的iOS模拟器默认运行x86_64架构，该架构下的Library Validation校验规则更宽松，不会拦截测试场景下的未签名bundle
• M1芯片默认以arm64原生架构运行模拟器，对加载的测试bundle、动态库有更严格的签名校验要求，不符合要求的组件会被直接拦截加载

解决方案 #

方案1：排除模拟器arm64架构（快速生效，无需修改签名配置） #

操作步骤：

1. 打开Xcode项目，选中单元测试Target
2. 进入Build Settings页面，找到Excluded Architectures配置项
3. 在Debug配置下，为Any iOS Simulator SDK添加值arm64，强制模拟器在M1设备上也通过Rosetta转译运行x86_64架构，完全对齐Intel设备的运行逻辑
4. 按Command+Shift+K清理Xcode构建缓存，重新运行测试即可

方案2：调整签名配置（保留arm64原生运行，性能更好） #

如果需要使用M1原生架构运行模拟器获得更高性能，可以调整签名相关配置：

1. 同时选中主项目Target和单元测试Target，分别进入Build Settings页面
2. 找到Other Code Signing Flags配置项，在Debug配置下添加参数--generate-entitlement-der
3. 找到Enable Hardened Runtime配置项，Debug模式下设置为NO
4. 清理构建缓存后重新运行测试

内容的提问来源于stack exchange，提问作者Colin Humber