add: [imp] expected ut

include/libimp/expected.h

@@ -246,7 +246,8 @@ struct storage : value_getter<storage<T, E>, T, E> {
 
   storage(storage &&other)
     : getter_t(std::move(other))
-    , has_value_(std::exchange(other.has_value_, false)) {}
+    /// After construction, has_value() is equal to other.has_value().
+    , has_value_(other.has_value_) {}
 
   template <typename T_, typename E_>
   storage(storage<T_, E_> const &other)
@@ -256,7 +257,8 @@ struct storage : value_getter<storage<T, E>, T, E> {
   template <typename T_, typename E_>
   storage(storage<T_, E_> &&other)
     : getter_t(std::move(other))
-    , has_value_(std::exchange(other.has_value_, false)) {}
+    /// After construction, has_value() is equal to other.has_value().
+    , has_value_(other.has_value_) {}
 
   bool has_value() const noexcept {
     return has_value_;
@@ -331,7 +333,7 @@ class expected : public detail_expected::storage<typename std::remove_cv<T>::typ
 
   expected()
     : detail_expected::storage<value_type, E>(in_place) {}
-  
+
   expected &operator=(expected other) {
     this->swap(other);
     return *this;

test/imp/test_imp_expected.cpp

@@ -0,0 +1,146 @@
+
+#include <utility>
+#include <cstdio>
+#include <cstdint>
+
+#include "gtest/gtest.h"
+
+#include "libimp/expected.h"
+
+namespace {
+
+class test_val {
+public:
+  int val = 0;
+  int dc_ = 0;
+  int cc_ = 0;
+  int mv_ = 0;
+
+  test_val() {
+    dc_ += 1;
+    std::printf("test_val construct.\n");
+  }
+  test_val(test_val const &o)
+    : val(o.val) {
+    cc_ = o.cc_ + 1;
+    std::printf("test_val copy construct.\n");
+  }
+  test_val(test_val &&o) noexcept
+    : val(std::exchange(o.val, 0)) {
+    mv_ = o.mv_ + 1;
+    std::printf("test_val move construct.\n");
+  }
+  ~test_val() {
+    std::printf("test_val destruct.\n");
+  }
+
+  test_val &operator=(test_val &&o) noexcept {
+    mv_ = o.mv_ + 1;
+    val = std::exchange(o.val, 0);
+    return *this;
+  }
+
+  test_val(int v)
+    : val(v) {
+    std::printf("test_val value initialization.\n");
+  }
+
+  bool operator==(test_val const &rhs) const {
+    return val == rhs.val;
+  }
+};
+
+class test_err {
+public:
+  int dc_ = 0;
+  int cc_ = 0;
+  int mv_ = 0;
+  std::int64_t val = 0;
+
+  test_err() {
+    dc_ += 1;
+    std::printf("test_err construct.\n");
+  }
+  test_err(test_err const &o)
+    : val(o.val) {
+    cc_ = o.cc_ + 1;
+    std::printf("test_err copy construct.\n");
+  }
+  test_err(test_err &&o) noexcept
+    : val(std::exchange(o.val, 0)) {
+    mv_ = o.mv_ + 1;
+    std::printf("test_err move construct.\n");
+  }
+  ~test_err() {
+    std::printf("test_err destruct.\n");
+  }
+
+  test_err &operator=(test_err &&o) noexcept {
+    mv_ = o.mv_ + 1;
+    val = std::exchange(o.val, 0);
+    return *this;
+  }
+
+  test_err(int v)
+    : val(v) {
+    std::printf("test_err value initialization.\n");
+  }
+
+  bool operator==(test_err const &rhs) const {
+    return val == rhs.val;
+  }
+};
+
+} // namespace
+
+TEST(expected, in_place) {
+  imp::expected<test_val, test_err> e1;
+  EXPECT_TRUE(e1);
+  EXPECT_EQ(e1.value().dc_, 1);
+  EXPECT_EQ(e1.value().val, 0);
+
+  imp::expected<test_val, test_err> e2 {imp::in_place, 123};
+  EXPECT_TRUE(e2);
+  EXPECT_EQ(e2.value().dc_, 0);
+  EXPECT_EQ(e2.value().val, 123);
+}
+
+TEST(expected, unexpected) {
+  imp::expected<test_val, test_err> e1 {imp::unexpected};
+  EXPECT_FALSE(e1);
+  EXPECT_EQ(e1.error().dc_, 1);
+  EXPECT_EQ(e1.error().val, 0);
+
+  imp::expected<test_val, test_err> e2 {imp::unexpected, 321};
+  EXPECT_FALSE(e2);
+  EXPECT_EQ(e2.error().dc_, 0);
+  EXPECT_EQ(e2.error().val, 321);
+}
+
+TEST(expected, copy_and_move) {
+  imp::expected<test_val, test_err> e1 {imp::in_place, 123};
+  imp::expected<test_val, test_err> e2 {e1};
+  EXPECT_TRUE(e1);
+  EXPECT_TRUE(e2);
+  EXPECT_EQ(e1, e2);
+  EXPECT_EQ(e2.value().cc_, 1);
+  EXPECT_EQ(e2.value().val, 123);
+
+  imp::expected<test_val, test_err> e3 {imp::unexpected, 333};
+  imp::expected<test_val, test_err> e4 {e3};
+  EXPECT_FALSE(e3);
+  EXPECT_FALSE(e4);
+  EXPECT_EQ(e3, e4);
+  EXPECT_EQ(e4.error().cc_, 1);
+  EXPECT_EQ(e4.error().val, 333);
+
+  imp::expected<test_val, test_err> e5;
+  e5 = e1;
+  EXPECT_EQ(e1, e5);
+  EXPECT_EQ(e5.value().val, 123);
+
+  imp::expected<test_val, test_err> e6;
+  e6 = std::move(e5);
+  EXPECT_EQ(e1, e6);
+  EXPECT_EQ(e5.value().val, 0);
+}