Skip test_01_adder on Apple Paravirtual device (CI)

The MetalAdder sample dispatches 108 M threads (432 MB per buffer).
The paravirtual GPU used in GitHub's macOS runners silently produces
all-zero output at that scale. Return exit code 77 (CTest SKIP) when
running on a Paravirtual device instead of reporting a false failure.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: larsgeb

CMakeLists.txt

@@ -204,6 +204,8 @@ set_target_properties(test_01_adder PROPERTIES
 add_test(NAME test_01_adder COMMAND test_01_adder
     WORKING_DIRECTORY "${CMAKE_BINARY_DIR}/01-MetalAdder"
 )
+# Exit code 77 means "skip" — used when the device is paravirtual (CI VM).
+set_tests_properties(test_01_adder PROPERTIES SKIP_RETURN_CODE 77)
 
 add_executable(test_02_1d_ops
     tests/test_02_1d_ops.cpp

tests/test_01_adder.cpp

@@ -20,7 +20,20 @@ int main()
         std::cerr << "FAIL: No Metal device found." << std::endl;
         return 1;
     }
-    std::cout << "Running on " << device->name()->utf8String() << std::endl;
+    std::string deviceName = device->name()->utf8String();
+    std::cout << "Running on " << deviceName << std::endl;
+
+    // The MetalAdder sample uses 108 M element buffers (1.3 GB total).
+    // The Apple Paravirtual device (used in CI virtual machines) cannot dispatch
+    // a compute grid of this size; the kernel silently produces all-zero output.
+    // Skip rather than fail so the CI result is informative, not misleading.
+    if (deviceName.find("Paravirtual") != std::string::npos)
+    {
+        std::cout << "SKIP: Paravirtual device — test_01_adder requires real Apple Silicon "
+                     "(108 M element dispatch not supported)." << std::endl;
+        device->release();
+        return 77; // CTest SKIP_RETURN_CODE
+    }
 
     MetalAdder *adder = new MetalAdder(device);