Squashed 'third_party/optional/' content from commit 1baad184f

Change-Id: I9b2473a84dcf6d9892f1f7a9fd21b340796b6ff5
git-subtree-dir: third_party/optional
git-subtree-split: 1baad184f022a3a7502db094a984a86adedf9626
diff --git a/tests/constructors.cpp b/tests/constructors.cpp
new file mode 100644
index 0000000..fc87a97
--- /dev/null
+++ b/tests/constructors.cpp
@@ -0,0 +1,62 @@
+#include "catch.hpp"
+#include "optional.hpp"
+#include <vector>
+
+struct foo {
+  foo() = default;
+  foo(foo&) = delete;
+  foo(foo&&) {};
+};
+
+TEST_CASE("Constructors", "[constructors]") {
+  tl::optional<int> o1;
+  REQUIRE(!o1);
+
+  tl::optional<int> o2 = tl::nullopt;
+  REQUIRE(!o2);
+
+  tl::optional<int> o3 = 42;
+  REQUIRE(*o3 == 42);
+
+  tl::optional<int> o4 = o3;
+  REQUIRE(*o4 == 42);
+
+  tl::optional<int> o5 = o1;
+  REQUIRE(!o5);
+
+  tl::optional<int> o6 = std::move(o3);
+  REQUIRE(*o6 == 42);
+
+  tl::optional<short> o7 = 42;
+  REQUIRE(*o7 == 42);
+
+  tl::optional<int> o8 = o7;
+  REQUIRE(*o8 == 42);
+
+  tl::optional<int> o9 = std::move(o7);
+  REQUIRE(*o9 == 42);
+
+  {
+    tl::optional<int &> o;
+    REQUIRE(!o);
+
+    tl::optional<int &> oo = o;
+    REQUIRE(!oo);
+  }
+
+  {
+    auto i = 42;
+    tl::optional<int &> o = i;
+    REQUIRE(o);
+    REQUIRE(*o == 42);
+
+    tl::optional<int &> oo = o;
+    REQUIRE(oo);
+    REQUIRE(*oo == 42);
+  }
+
+  std::vector<foo> v;
+  v.emplace_back();
+  tl::optional<std::vector<foo>> ov = std::move(v);
+  REQUIRE(ov->size() == 1);
+}