Legion: Add E4S testsuite stand alone test (#25285)

Co-authored-by: Tamara Dahlgren <35777542+tldahlgren@users.noreply.github.com>

var/spack/repos/builtin/packages/legion/package.py

@@ -332,3 +332,44 @@ def cmake_args(self):
             options.append('-DBUILD_MARCH:STRING=native')
 
         return options
+
+    @run_after('install')
+    def cache_test_sources(self):
+        """Copy the example source files after the package is installed to an
+        install test subdirectory for use during `spack test run`."""
+        self.cache_extra_test_sources([join_path('examples', 'local_function_tasks')])
+
+    def run_local_function_tasks_test(self):
+        """Run stand alone test: local_function_tasks"""
+
+        test_dir = join_path(self.test_suite.current_test_cache_dir,
+                             'examples', 'local_function_tasks')
+
+        if not os.path.exists(test_dir):
+            print('Skipping local_function_tasks test')
+            return
+
+        exe = 'local_function_tasks'
+
+        cmake_args = ['-DCMAKE_C_COMPILER={0}'.format(self.compiler.cc),
+                      '-DCMAKE_CXX_COMPILER={0}'.format(self.compiler.cxx),
+                      '-DLegion_DIR={0}'.format(join_path(self.prefix,
+                                                          'share',
+                                                          'Legion',
+                                                          'cmake'))]
+
+        self.run_test('cmake',
+                      options=cmake_args,
+                      purpose='test: generate makefile for {0} example'.format(exe),
+                      work_dir=test_dir)
+
+        self.run_test('make',
+                      purpose='test: build {0} example'.format(exe),
+                      work_dir=test_dir)
+
+        self.run_test(exe,
+                      purpose='test: run {0} example'.format(exe),
+                      work_dir=test_dir)
+
+    def test(self):
+        self.run_local_function_tasks_test()