diff --git a/CMakeLists.txt b/CMakeLists.txt
index 76e6a07..9e34115 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,6 +4,13 @@ include(CTest)
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O2")
 set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -g -fsanitize=address")
+include(FetchContent)
+FetchContent_Declare(
+  googletest
+  URL https://github.com/google/googletest/archive/refs/tags/v1.14.0.zip
+)
+FetchContent_MakeAvailable(googletest)
+include(GoogleTest)
 add_subdirectory(vector)
 add_subdirectory(priority_queue)
 add_subdirectory(map)
diff --git a/map/CMakeLists.txt b/map/CMakeLists.txt
index fba5e91..83e4d26 100644
--- a/map/CMakeLists.txt
+++ b/map/CMakeLists.txt
@@ -29,4 +29,5 @@ add_test(NAME mp_four_mem COMMAND sh -c "${CMAKE_CURRENT_BINARY_DIR}/mp_four_mem
 add_test(NAME mp_five COMMAND sh -c "${CMAKE_CURRENT_BINARY_DIR}/mp_five >/tmp/five_out.txt\
         && diff -u ${CMAKE_CURRENT_SOURCE_DIR}/data/five/answer.txt /tmp/five_out.txt>/tmp/five_diff.txt")
 add_test(NAME mp_five_mem COMMAND sh -c "${CMAKE_CURRENT_BINARY_DIR}/mp_five_mem >/tmp/five_mem_out.txt\
-        && diff -u ${CMAKE_CURRENT_SOURCE_DIR}/data/five/answer.txt /tmp/five_mem_out.txt>/tmp/five_mem_diff.txt")
\ No newline at end of file
+        && diff -u ${CMAKE_CURRENT_SOURCE_DIR}/data/five/answer.txt /tmp/five_mem_out.txt>/tmp/five_mem_diff.txt")
+add_subdirectory(test)
\ No newline at end of file
diff --git a/map/src/map.hpp b/map/src/map.hpp
index f2504e2..44cebf2 100644
--- a/map/src/map.hpp
+++ b/map/src/map.hpp
@@ -243,7 +243,15 @@ class map {
     map *domain;
 
    public:
+    // Add some type traits
+    typedef std::bidirectional_iterator_tag iterator_category;
+    typedef pair<const Key, T> value_type;
+    typedef std::ptrdiff_t difference_type;
+    typedef value_type *pointer;
+    typedef value_type &reference;
+
     friend const_iterator;
+    friend map;
     iterator() : raw_pointer(nullptr), domain(nullptr) {}
     iterator(const iterator &other) : raw_pointer(other.raw_pointer), domain(other.domain) {}
     iterator(RedBlackTreeNodeType *raw_pointer, map *domain) : raw_pointer(raw_pointer), domain(domain) {}
@@ -326,7 +334,15 @@ class map {
     const map *domain;
 
    public:
+    // Add some type traits
+    typedef std::bidirectional_iterator_tag iterator_category;
+    typedef pair<const Key, T> value_type;
+    typedef std::ptrdiff_t difference_type;
+    typedef value_type *pointer;
+    typedef value_type &reference;
+
     friend iterator;
+    friend map;
     const_iterator() : raw_pointer(nullptr), domain(nullptr) {}
     const_iterator(const const_iterator &other) : raw_pointer(other.raw_pointer), domain(other.domain) {}
     const_iterator(const iterator &other) : raw_pointer(other.raw_pointer), domain(other.domain) {}
@@ -409,7 +425,7 @@ class map {
     other.tree_root = nullptr;
   }
   /**
-   * TODO assignment operator
+   * assignment operator
    */
   map &operator=(const map &other) {
     if (this == &other) return *this;
@@ -417,6 +433,7 @@ class map {
     delete tree_root;
     node_count = other.node_count;
     CopyFrom(tree_root, other.tree_root);
+    return *this;
   }
   map &operator=(map &&other) {
     if (this == &other) return *this;
@@ -426,6 +443,7 @@ class map {
     tree_root = other.tree_root;
     other.node_count = 0;
     other.tree_root = nullptr;
+    return *this;
   }
   ~map() {
     if (tree_root) tree_root->ReleaseAll();
@@ -447,7 +465,6 @@ class map {
     return result->val.second;
   }
   /**
-   * TODO
    * access specified element
    * Returns a reference to the value that is mapped to a key equivalent to key,
    *   performing an insertion if such key does not already exist.
@@ -521,7 +538,9 @@ class map {
    *
    * throw if pos pointed to a bad element (pos == this->end() || pos points an element out of this)
    */
-  void erase(iterator pos) {}
+  void erase(iterator pos) {
+    if (pos.domain != this || pos.raw_pointer == nullptr) throw invalid_iterator();
+  }
   /**
    * Returns the number of elements with key
    *   that compares equivalent to the specified argument,
diff --git a/map/test/CMakeLists.txt b/map/test/CMakeLists.txt
new file mode 100644
index 0000000..3fa8324
--- /dev/null
+++ b/map/test/CMakeLists.txt
@@ -0,0 +1,9 @@
+add_executable(
+  test_mp_basic
+  test_basic.cpp
+)
+target_link_libraries(
+  test_mp_basic
+  GTest::gtest_main
+)
+gtest_discover_tests(test_mp_basic)
\ No newline at end of file
diff --git a/map/test/test_basic.cpp b/map/test/test_basic.cpp
new file mode 100644
index 0000000..d07353b
--- /dev/null
+++ b/map/test/test_basic.cpp
@@ -0,0 +1,15 @@
+#include <gtest/gtest.h>
+#include "map.hpp"
+
+TEST(BasicTests, GTestItSelf) {
+  // Expect two strings not to be equal.
+  EXPECT_STRNE("hello", "world");
+  // Expect equality.
+  EXPECT_EQ(7 * 6, 42);
+}
+
+TEST(BasicTests, ConstructorAndEmptySize) {
+  sjtu::map<int, int> map;
+  EXPECT_EQ(map.empty(), true);
+  EXPECT_EQ(map.size(), 0);
+}
\ No newline at end of file