diff --git a/test/iso_week/year.pass.cpp b/test/iso_week/year.pass.cpp
new file mode 100644
index 0000000..6c1189a
--- /dev/null
+++ b/test/iso_week/year.pass.cpp
@@ -0,0 +1,120 @@
+// The MIT License (MIT)
+// 
+// Copyright (c) 2015 Howard Hinnant
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+// class year
+// {
+// public:
+//     explicit constexpr year(int y) noexcept;
+// 
+//     year& operator++()    noexcept;
+//     year  operator++(int) noexcept;
+//     year& operator--()    noexcept;
+//     year  operator--(int) noexcept;
+// 
+//     year& operator+=(const years& y) noexcept;
+//     year& operator-=(const years& y) noexcept;
+// 
+//     constexpr explicit operator int() const noexcept;
+//     constexpr bool ok() const noexcept;
+// 
+//     static constexpr year min() noexcept;
+//     static constexpr year max() noexcept;
+// };
+
+// constexpr bool operator==(const year& x, const year& y) noexcept;
+// constexpr bool operator!=(const year& x, const year& y) noexcept;
+// constexpr bool operator< (const year& x, const year& y) noexcept;
+// constexpr bool operator> (const year& x, const year& y) noexcept;
+// constexpr bool operator<=(const year& x, const year& y) noexcept;
+// constexpr bool operator>=(const year& x, const year& y) noexcept;
+
+// constexpr year  operator+(const year&  x, const years& y) noexcept;
+// constexpr year  operator+(const years& x, const year&  y) noexcept;
+// constexpr year  operator-(const year&  x, const years& y) noexcept;
+// constexpr years operator-(const year&  x, const year&  y) noexcept;
+
+// std::ostream& operator<<(std::ostream& os, const year& y);
+// inline namespace literals {
+// constexpr year operator "" _y(unsigned long long y) noexcept;
+// }
+
+#include "iso_week.h"
+
+#include <cassert>
+#include <sstream>
+#include <type_traits>
+
+static_assert( std::is_trivially_destructible<iso_week::year>{}, "");
+static_assert(!std::is_default_constructible<iso_week::year>{}, "");
+static_assert( std::is_trivially_copy_constructible<iso_week::year>{}, "");
+static_assert( std::is_trivially_copy_assignable<iso_week::year>{}, "");
+static_assert( std::is_trivially_move_constructible<iso_week::year>{}, "");
+static_assert( std::is_trivially_move_assignable<iso_week::year>{}, "");
+
+static_assert(std::is_trivially_copyable<iso_week::year>{}, "");
+static_assert(std::is_standard_layout<iso_week::year>{}, "");
+static_assert(std::is_literal_type<iso_week::year>{}, "");
+
+static_assert( std::is_nothrow_constructible<iso_week::year, int>{}, "");
+static_assert(!std::is_convertible<int, iso_week::year>{}, "");
+static_assert( std::is_nothrow_constructible<int, iso_week::year>{}, "");
+static_assert(!std::is_convertible<iso_week::year, int>{}, "");
+static_assert(static_cast<int>(iso_week::year{-1}) == -1, "");
+
+int
+main()
+{
+    using namespace iso_week;
+
+    static_assert(year{2015} == 2015_y, "");
+    static_assert(int{year{2015}} == 2015, "");
+    static_assert(year{2015} != 2016_y, "");
+    static_assert(year{2015} < 2016_y, "");
+    static_assert(year{2016} > 2015_y, "");
+    static_assert(year{2015} <= 2015_y, "");
+    static_assert(year{2016} >= 2015_y, "");
+
+    auto y = year{2014};
+    assert(++y == year{2015});
+    assert(y == year{2015});
+    assert(y++ == year{2015});
+    assert(y == year{2016});
+    assert(--y == year{2015});
+    assert(y == year{2015});
+    assert(y-- == year{2015});
+    assert(y == year{2014});
+
+    static_assert(year::min().ok(), "");
+    static_assert(year{2015}.ok(), "");
+    static_assert(year{2016}.ok(), "");
+    static_assert(year::max().ok(), "");
+
+    static_assert(2015_y - 2010_y == years{5}, "");
+    static_assert(2015_y - years{5} == 2010_y, "");
+    static_assert(2015_y == years{5} + 2010_y, "");
+    static_assert(2015_y == 2010_y + years{5}, "");
+
+    y = 2015_y;
+    std::ostringstream os;
+    os << y;
+    assert(os.str() == "2015");
+}
diff --git a/test/iso_week/year_p_year.fail.cpp b/test/iso_week/year_p_year.fail.cpp
new file mode 100644
index 0000000..63180a5
--- /dev/null
+++ b/test/iso_week/year_p_year.fail.cpp
@@ -0,0 +1,32 @@
+// The MIT License (MIT)
+// 
+// Copyright (c) 2015 Howard Hinnant
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+// year + year not allowed
+
+#include "iso_week.h"
+
+int
+main()
+{
+    using namespace iso_week;
+    auto x = 2015_y + 2015_y;
+}
diff --git a/test/iso_week/years_m_year.fail.cpp b/test/iso_week/years_m_year.fail.cpp
new file mode 100644
index 0000000..3821db5
--- /dev/null
+++ b/test/iso_week/years_m_year.fail.cpp
@@ -0,0 +1,32 @@
+// The MIT License (MIT)
+// 
+// Copyright (c) 2015 Howard Hinnant
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+// years - year not allowed
+
+#include "iso_week.h"
+
+int
+main()
+{
+    using namespace iso_week;
+    auto x = years{3} - 2015_y;
+}