VTK-m: Add testlib variant. (#28324)

var/spack/repos/builtin/packages/vtk-m/package.py

@@ -55,6 +55,7 @@ class VtkM(CMakePackage, CudaPackage):
     variant("rendering", default=True, description="build rendering support")
     variant("64bitids", default=False,
             description="enable 64 bits ids")
+    variant("testlib", default=False, description="build test library")
 
     # Device variants
     variant("cuda", default=False, description="build cuda support")
@@ -161,6 +162,10 @@ def cmake_args(self):
             else:
                 options.append("-DVTKm_USE_64BIT_IDS:BOOL=OFF")
 
+            # Support for the testing header files
+            if "+testlib" in spec and spec.satisfies('@1.7.0:'):
+                options.append("-DVTKm_ENABLE_TESTING_LIBRARY:BOOL=ON")
+
             if spec.variants["build_type"].value != 'Release':
                 options.append("-DVTKm_NO_ASSERT:BOOL=ON")