Optional copy constructor and assignment operator (#23)

* Regression tests for crash in optional

* Copy constructor and assignment operator for optional

Author: jkalias

include/optional.h

@@ -47,6 +47,23 @@ class optional {
     {
         reset();
     }
+
+    optional& operator=(optional const& other)
+    {
+        _value = nullptr;
+        if (other.has_value()) {
+            _value = new T{ other.value() };
+        }
+        return *this;
+    }
+
+    optional(const optional& other)
+    {
+        _value = nullptr;
+        if (other.has_value()) {
+            _value = new T{ other.value() };
+        }
+    }
 
     optional(T const& val)
     : _value(new T{val})

tests/optional_test.cc

@@ -36,9 +36,65 @@ TEST(OptionalTest, ValidTest) {
     EXPECT_EQ(5, index.value());
 }
 
-TEST(OptionalTest, AssignmentTest) {
+TEST(OptionalTest, AssignmentFromValueTest) {
     optional_t<int> index(5);
     index = 3;
     EXPECT_TRUE(index.has_value());
     EXPECT_EQ(3, index.value());
 }
+
+TEST(OptionalTest, AssignmentFromOptionalTest) {
+    optional_t<int> v1(5);
+    const optional_t<int> v2(2);
+    v1 = v2;
+    EXPECT_TRUE(v1.has_value());
+    EXPECT_EQ(2, v1.value());
+	EXPECT_TRUE(v2.has_value());
+    EXPECT_EQ(2, v2.value());
+}
+
+TEST(OptionalTest, AssignmentFromNullOptionalTest) {
+    optional_t<int> v1(5);
+    const optional_t<int> v2;
+    v1 = v2;
+    EXPECT_FALSE(v1.has_value());
+    EXPECT_FALSE(v2.has_value());
+}
+
+TEST(OptionalTest, AssignmentToNullFromValueTest) {
+    optional_t<int> index;
+    index = 3;
+    EXPECT_TRUE(index.has_value());
+    EXPECT_EQ(3, index.value());
+}
+
+TEST(OptionalTest, AssignmentToNullFromOptionalTest) {
+    optional_t<int> v1;
+    const optional_t<int> v2(2);
+    v1 = v2;
+    EXPECT_TRUE(v1.has_value());
+    EXPECT_EQ(2, v1.value());
+	EXPECT_TRUE(v2.has_value());
+    EXPECT_EQ(2, v2.value());
+}
+
+TEST(OptionalTest, AssignmentToNullFromNullOptionalTest) {
+    optional_t<int> v1;
+    const optional_t<int> v2;
+    v1 = v2;
+    EXPECT_FALSE(v1.has_value());
+    EXPECT_FALSE(v2.has_value());
+}
+
+TEST(OptionalTest, CopyConstructorTest) {
+    const optional_t<int> v2(5);
+    const optional_t<int> v1(v2);
+    EXPECT_TRUE(v1.has_value());
+    EXPECT_EQ(5, v2.value());
+}
+
+TEST(OptionalTest, CopyConstructorNullTest) {
+    const optional_t<int> v2;
+    const optional_t<int> v1(v2);
+    EXPECT_FALSE(v1.has_value());
+}