Split test_python_types.cpp into builtin_casters, stl and pytypes
diff --git a/tests/test_stl.cpp b/tests/test_stl.cpp
new file mode 100644
index 0000000..5288097
--- /dev/null
+++ b/tests/test_stl.cpp
@@ -0,0 +1,163 @@
+/*
+    tests/test_stl.cpp -- STL type casters
+
+    Copyright (c) 2017 Wenzel Jakob <wenzel.jakob@epfl.ch>
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+*/
+
+#include "pybind11_tests.h"
+#include <pybind11/stl.h>
+
+// Class that can be move- and copy-constructed, but not assigned
+struct NoAssign {
+    int value;
+
+    explicit NoAssign(int value = 0) : value(value) { }
+    NoAssign(const NoAssign &) = default;
+    NoAssign(NoAssign &&) = default;
+
+    NoAssign &operator=(const NoAssign &) = delete;
+    NoAssign &operator=(NoAssign &&) = delete;
+};
+
+/// Issue #528: templated constructor
+struct TplCtorClass {
+    template <typename T> TplCtorClass(const T &) { }
+    bool operator==(const TplCtorClass &) const { return true; }
+};
+
+namespace std {
+    template <>
+    struct hash<TplCtorClass> { size_t operator()(const TplCtorClass &) const { return 0; } };
+}
+
+
+TEST_SUBMODULE(stl, m) {
+    // test_vector
+    m.def("cast_vector", []() { return std::vector<int>{1}; });
+    m.def("load_vector", [](const std::vector<int> &v) { return v.at(0) == 1 && v.at(1) == 2; });
+
+    // test_array
+    m.def("cast_array", []() { return std::array<int, 2> {{1 , 2}}; });
+    m.def("load_array", [](const std::array<int, 2> &a) { return a[0] == 1 && a[1] == 2; });
+
+    // test_valarray
+    m.def("cast_valarray", []() { return std::valarray<int>{1, 4, 9}; });
+    m.def("load_valarray", [](const std::valarray<int>& v) {
+        return v.size() == 3 && v[0] == 1 && v[1] == 4 && v[2] == 9;
+    });
+
+    // test_map
+    m.def("cast_map", []() { return std::map<std::string, std::string>{{"key", "value"}}; });
+    m.def("load_map", [](const std::map<std::string, std::string> &map) {
+        return map.at("key") == "value" && map.at("key2") == "value2";
+    });
+
+    // test_set
+    m.def("cast_set", []() { return std::set<std::string>{"key1", "key2"}; });
+    m.def("load_set", [](const std::set<std::string> &set) {
+        return set.count("key1") && set.count("key2") && set.count("key3");
+    });
+
+    struct MoveOutContainer {
+        struct Value { int value; };
+
+        std::list<Value> move_list() const { return {{0}, {1}, {2}}; }
+    };
+
+    py::class_<MoveOutContainer::Value>(m, "MoveOutContainerValue")
+        .def_readonly("value", &MoveOutContainer::Value::value);
+
+    py::class_<MoveOutContainer>(m, "MoveOutContainer")
+        .def(py::init<>())
+        .def_property_readonly("move_list", &MoveOutContainer::move_list);
+
+    py::class_<NoAssign>(m, "NoAssign", "Class with no C++ assignment operators")
+        .def(py::init<>())
+        .def(py::init<int>());
+
+#ifdef PYBIND11_HAS_OPTIONAL
+    m.attr("has_optional") = true;
+
+    using opt_int = std::optional<int>;
+    using opt_no_assign = std::optional<NoAssign>;
+    m.def("double_or_zero", [](const opt_int& x) -> int {
+        return x.value_or(0) * 2;
+    });
+    m.def("half_or_none", [](int x) -> opt_int {
+        return x ? opt_int(x / 2) : opt_int();
+    });
+    m.def("test_nullopt", [](opt_int x) {
+        return x.value_or(42);
+    }, py::arg_v("x", std::nullopt, "None"));
+    m.def("test_no_assign", [](const opt_no_assign &x) {
+        return x ? x->value : 42;
+    }, py::arg_v("x", std::nullopt, "None"));
+
+    m.def("nodefer_none_optional", [](std::optional<int>) { return true; });
+    m.def("nodefer_none_optional", [](py::none) { return false; });
+#endif
+
+#ifdef PYBIND11_HAS_EXP_OPTIONAL
+    m.attr("has_exp_optional") = true;
+
+    using exp_opt_int = std::experimental::optional<int>;
+    using exp_opt_no_assign = std::experimental::optional<NoAssign>;
+    m.def("double_or_zero_exp", [](const exp_opt_int& x) -> int {
+        return x.value_or(0) * 2;
+    });
+    m.def("half_or_none_exp", [](int x) -> exp_opt_int {
+        return x ? exp_opt_int(x / 2) : exp_opt_int();
+    });
+    m.def("test_nullopt_exp", [](exp_opt_int x) {
+        return x.value_or(42);
+    }, py::arg_v("x", std::experimental::nullopt, "None"));
+    m.def("test_no_assign_exp", [](const exp_opt_no_assign &x) {
+        return x ? x->value : 42;
+    }, py::arg_v("x", std::experimental::nullopt, "None"));
+#endif
+
+#ifdef PYBIND11_HAS_VARIANT
+    struct visitor {
+        const char *operator()(int) { return "int"; }
+        const char *operator()(std::string) { return "std::string"; }
+        const char *operator()(double) { return "double"; }
+        const char *operator()(std::nullptr_t) { return "std::nullptr_t"; }
+    };
+
+    m.def("load_variant", [](std::variant<int, std::string, double, std::nullptr_t> v) {
+        return std::visit(visitor(), v);
+    });
+
+    m.def("load_variant_2pass", [](std::variant<double, int> v) {
+        return std::visit(visitor(), v);
+    });
+
+    m.def("cast_variant", []() {
+        using V = std::variant<int, std::string>;
+        return py::make_tuple(V(5), V("Hello"));
+    });
+#endif
+
+    /// #528: templated constructor
+    m.def("tpl_ctor_vector", [](std::vector<TplCtorClass> &) {});
+    m.def("tpl_ctor_map", [](std::unordered_map<TplCtorClass, TplCtorClass> &) {});
+    m.def("tpl_ctor_set", [](std::unordered_set<TplCtorClass> &) {});
+#if defined(PYBIND11_HAS_OPTIONAL)
+    m.def("tpl_constr_optional", [](std::optional<TplCtorClass> &) {});
+#elif defined(PYBIND11_HAS_EXP_OPTIONAL)
+    m.def("tpl_constr_optional", [](std::experimental::optional<TplCtorClass> &) {});
+#endif
+
+    // test_vec_of_reference_wrapper
+    // #171: Can't return STL structures containing reference wrapper
+    m.def("return_vec_of_reference_wrapper", [](std::reference_wrapper<UserType> p4) {
+        static UserType p1{1}, p2{2}, p3{3};
+        return std::vector<std::reference_wrapper<UserType>> {
+            std::ref(p1), std::ref(p2), std::ref(p3), p4
+        };
+    });
+
+}