Add sketch of tests

Author: hlopko

test/Interop/Cxx/templates/Inputs/module.modulemap

@@ -37,3 +37,15 @@ module Mangling {
 module LinkageOfSwiftSymbolsForImportedTypes {
   header "linkage-of-swift-symbols-for-imported-types.h"
 }
+
+module VariadicClassTemplate {
+  header "variadic-class-template.h"
+}
+
+module NonTypeTemplateParameter {
+  header "non-type-template-parameter.h"
+}
+
+module TemplateTemplateParameter {
+  header "template-template-parameter.h"
+}

test/Interop/Cxx/templates/Inputs/non-type-parameter.h

@@ -0,0 +1,11 @@
+#ifndef TEST_INTEROP_CXX_TEMPLATES_INPUTS_NON_TYPE_PARAMETER_H
+#define TEST_INTEROP_CXX_TEMPLATES_INPUTS_NON_TYPE_PARAMETER_H
+
+template<class T, auto Size>
+struct MagicArray {
+    T t[Size];
+};
+
+typedef MagicArray<int, 2> MagicIntPair;
+
+#endif // TEST_INTEROP_CXX_TEMPLATES_INPUTS_NON_TYPE_PARAMETER_H

test/Interop/Cxx/templates/Inputs/template-template-parameter.h

@@ -0,0 +1,21 @@
+#ifndef TEST_INTEROP_CXX_TEMPLATES_INPUTS_TEMPLATE_TEMPLATE_PARAMETER_H
+#define TEST_INTEROP_CXX_TEMPLATES_INPUTS_TEMPLATE_TEMPLATE_PARAMETER_H
+
+template<template <class> class V>
+struct Asdf {
+  V<IntWrapper> i;
+};
+
+struct IntWrapper {
+  int value;
+  int getValue() const { return value; }
+};
+
+template <class T>
+struct MagicWrapper {
+  T t;
+  int getValuePlusArg(int arg) const { return t.getValue() + arg; }
+};
+
+typedef Asdf<MagicWrapper> Hohoho;
+#endif // TEST_INTEROP_CXX_TEMPLATES_INPUTS_TEMPLATE_TEMPLATE_PARAMETER_H

test/Interop/Cxx/templates/Inputs/variadic-class-template.h

@@ -0,0 +1,23 @@
+#ifndef TEST_INTEROP_CXX_TEMPLATES_INPUTS_VARIADIC_CLASS_TEMPLATE_H
+#define TEST_INTEROP_CXX_TEMPLATES_INPUTS_VARIADIC_CLASS_TEMPLATE_H
+
+template <class... Ts> struct Tuple {};
+
+template <class T, class... Ts>
+struct Tuple<T, Ts...> : Tuple<Ts...> {
+  Tuple(T t, Ts... ts) : Tuple<Ts...>(ts...), t(t) {}
+
+  T get() { return t; }
+  T rest() { return Tuple<Ts...>::get(); }
+
+  T t;
+};
+
+struct IntWrapper {
+  int value;
+  int getValue() const { return value; }
+};
+
+typedef Tuple<IntWrapper, IntWrapper> Pair;
+
+#endif // TEST_INTEROP_CXX_TEMPLATES_INPUTS_VARIADIC_CLASS_TEMPLATE_H

test/Interop/Cxx/templates/non-type-parameter.swift.swift

@@ -0,0 +1,16 @@
+// RUN: %target-run-simple-swift(-I %S/Inputs -Xfrontend -enable-cxx-interop -Xcc -std=c++17)
+//
+// REQUIRES: executable_test
+
+import NonTypeParameter
+import StdlibUnittest
+
+var TemplatesTestSuite = TestSuite("TemplatesTestSuite")
+
+TemplatesTestSuite.test("variadic-class-template") {
+  let pair = MagicIntPair()
+  pair.t = [10, 20]
+  expectEqual(pair.t, [10, 20])
+}
+
+runAllTests()

test/Interop/Cxx/templates/template-template-parameter.swift

@@ -0,0 +1,16 @@
+// RUN: %target-run-simple-swift(-I %S/Inputs -Xfrontend -enable-cxx-interop -Xcc -std=c++17)
+//
+// REQUIRES: executable_test
+
+import NonTypeParameter
+import StdlibUnittest
+
+var TemplatesTestSuite = TestSuite("TemplatesTestSuite")
+
+TemplatesTestSuite.test("variadic-class-template") {
+  let a = IntWrapper(value: 42)
+  let hohoho = Hohoho()
+  hohoho.i = a
+}
+
+runAllTests()

test/Interop/Cxx/templates/variadic-class-template.swift

@@ -0,0 +1,18 @@
+// RUN: %target-run-simple-swift(-I %S/Inputs -Xfrontend -enable-cxx-interop -Xcc -std=c++17)
+//
+// REQUIRES: executable_test
+
+import VariadicClassTemplate
+import StdlibUnittest
+
+var TemplatesTestSuite = TestSuite("TemplatesTestSuite")
+
+TemplatesTestSuite.test("variadic-class-template") {
+  let a = IntWrapper(value: 10)
+  let b = IntWrapper(value: 20)
+  let pair = Pair(a, b)
+  expectEqual(pair.get(), 10)
+  expectEqual(pair.rest().get(), 20)
+}
+
+runAllTests()