Add substitutions and a test for the SourceKit stress tester executables

lit.cfg

@@ -232,3 +232,16 @@ else:
 for name in ('swift-build', 'FileCheck', 'readelf'):
   config.substitutions.append((' {0} '.format(name),
                                ' unquoted-command-name-{0} '.format(name)))
+
+# Add substitutions for SourceKit stress tester executables
+sk_stress_test_path = lit_config.params.get(
+    "sk-stress-test",
+    os.path.join(package_path, "usr", "bin", "sk-stress-test"))
+sk_swiftc_wrapper_path = lit_config.params.get(
+    "sk-swiftc-wrapper",
+    os.path.join(package_path, "usr", "bin", "sk-swiftc-wrapper"))
+
+lit_config.note("testing using 'sk-stress-test': {}".format(sk_stress_test_path))
+lit_config.note("testing using 'sk-swiftc-wrapper': {}".format(sk_swiftc_wrapper_path))
+config.substitutions.append( ('%{sk-stress-test}', sk_stress_test_path) )
+config.substitutions.append( ('%{sk-swiftc-wrapper}', sk_swiftc_wrapper_path) )

sk-stress-test.txt

@@ -0,0 +1,20 @@
+// Trivial test for the SourceKit stress tester and compiler wrapper.
+//
+// REQUIRES: platform=Darwin
+//
+// RUN: rm -rf %t.dir
+// RUN: mkdir -p %t.dir
+// RUN: cp %s %t.dir/test.swift
+//
+// 1) Make sure both exit successfully running over a valid file
+// RUN: %{sk-stress-test} %t.dir/test.swift swiftc %t.dir/test.swift
+// RUN: %{sk-swiftc-wrapper} %t.dir/test.swift
+//
+// 2) Make sure the wrapper fails when the underlying compilation fails
+// RUN: echo " undefined_symbol " >> %t.dir/test.swift
+// RUN: %{not} %{sk-swiftc-wrapper} %t.dir/test.swift
+//
+
+func foo() {
+	print("hello")
+}