Interop Testing

Testing Interop in the CoreCLR repo follows other tests in the repo and utilizes a series of small EXE projects that exercise a specific feature.

See Documentation/building/test-configuration.md for details on how to create new tests.

Assets

There should be no more than 1 project type per folder (i.e. a folder can contain a managed and native but no more than 1 of each).

Ancillary source assets for all tests should be located in Interop/common and can be easily added to all managed tests via the Interop.settings.targets file or native tests via Interop.cmake.

A common pattern for testing is using the Assert utilities. This class is part of the CoreCLRTestLibrary which is included in all test projects by the Interop.settings.targets import. In order to use, add the following using TestLibrary; in the relevant test file.

Managed

Managed tests should be designed to use the SDK style project system provided by dotnet-cli.

Native

Native test assets use CMake and can leverage any of the product build assets. In addition to the use of CMake projects, all native projects should include the following:

include ("${CLR_INTEROP_TEST_ROOT}/Interop.cmake")

The above import allows all native projects to be maintained in a unified way.

Native assets should be written in a manner that is as portable as possible across platforms (i.e. Windows, MacOS, Linux).

Note Native assets are hard to get right and in many instances scenarios they test may not apply to all platforms. See details in Documentation/building/test-configuration.md about how to disable a tests for a specific platform.

Testing Areas

Interop testing is divided into several areas.

P/Invoke

The P/Invoke bucket represents tests that involve a Platform Invoke scenario.

Testing P/Invoke has two aspects:

1. Marshaling types
   • Primitives
   • Array
   • Structure
   • Union
   • String
   • Delegate
2. DllImportAttribute
   • Attribute values
   • Search paths

Marshal API

The Marshal API surface area testing is traditionally done via unit testing and far better suited in the library test folder. Cases where testing the API surface area requires native tests assets will be performed in the coreclr test folder repo.

NativeLibrary

This series has unit tests corresponding to System.Runtime.NativeLibrary APIs and related events in System.Runtime.Loader.AssemblyLoadContext.

Common Task steps

Adding new native project

1. Update coreclr/tests/src/Interop/CMakeLists.txt to include new test asset directory.
2. Verify project builds by running build-tests.cmd/build-tests.sh from repo root.

Adding new managed project

1. The build system automatically discovers managed test projects.
2. Verify project builds by running build-tests.cmd/build-tests.sh from repo root.