feat(tests): add kernel loading validation in test setup

Add additional import statements and validation steps to ensure the required kernel 'kernels-test/flattened-build' can be successfully loaded before proceeding with the test. This prevents test failures due to missing or incompatible kernel environments and provides clearer skip messages when the kernel is unavailable.

Author: meichangsu1

tests/kernel/test_function_kernel.py

@@ -41,10 +41,21 @@ def test_flattened_build_replaces_function(self):
             self.skipTest('CUDA not available in this environment.')
         try:
             from kernels import has_kernel
+            from kernels._versions import select_revision_or_version
+            from kernels.utils import get_kernel
         except Exception:
             self.skipTest('kernels package missing has_kernel.')
         if not has_kernel('kernels-test/flattened-build'):
             self.skipTest('kernels-test/flattened-build not available.')
+        try:
+            revision = select_revision_or_version(
+                'kernels-test/flattened-build',
+                revision=None,
+                version=None,
+            )
+            get_kernel('kernels-test/flattened-build', revision=revision)
+        except Exception as exc:
+            self.skipTest(f'kernels-test/flattened-build cannot be loaded in this env: {exc}')
 
         _ensure_test_packages()
         module_name = 'tests.kernel._tmp_flattened_build_module'