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diff --git a/libs/kstd/tests/src/flat_map.cpp b/libs/kstd/tests/src/flat_map.cpp
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+++ b/libs/kstd/tests/src/flat_map.cpp
@@ -0,0 +1,313 @@
+#include <kstd/flat_map>
+#include <kstd/tests/os_panic.hpp>
+
+#include <catch2/catch_test_macros.hpp>
+
+#include <functional>
+#include <type_traits>
+#include <utility>
+
+SCENARIO("Flat Map initialization and construction", "[flat_map]")
+{
+  GIVEN("An empty context")
+  {
+    WHEN("constructing by default")
+    {
+      auto map = kstd::flat_map<int, int>{};
+
+      THEN("the Flat Map does not contain elements")
+      {
+        REQUIRE_FALSE(map.contains(1));
+      }
+    }
+  }
+}
+
+SCENARIO("Flat Map modifiers", "[flat_map]")
+{
+  GIVEN("An empty Flat Map")
+  {
+    auto map = kstd::flat_map<int, int>{};
+
+    WHEN("emplacing a new element")
+    {
+      auto [it, inserted] = map.emplace(1, 100);
+
+      THEN("the map contains the new element")
+      {
+        REQUIRE(inserted);
+        REQUIRE(map.contains(1));
+      }
+    }
+
+    WHEN("emplacing an existing element")
+    {
+      map.emplace(1, 100);
+      auto [it, inserted] = map.emplace(1, 200);
+
+      THEN("the map does not insert the duplicate")
+      {
+        REQUIRE_FALSE(inserted);
+        REQUIRE(map.contains(1));
+      }
+    }
+  }
+}
+
+SCENARIO("Flat Map element access", "[flat_map]")
+{
+  GIVEN("A populated Flat Map")
+  {
+    auto map = kstd::flat_map<int, int>{};
+    map.emplace(1, 10);
+    map.emplace(2, 20);
+    map.emplace(3, 30);
+
+    WHEN("accessing an existing element with at()")
+    {
+      auto & val = map.at(2);
+
+      THEN("it returns a reference to the mapped value")
+      {
+        REQUIRE(val == 20);
+      }
+
+      THEN("the mapped value can be modified")
+      {
+        val = 200;
+        REQUIRE(map.at(2) == 200);
+      }
+    }
+
+    WHEN("accessing a non-existent element with at()")
+    {
+      THEN("it panics")
+      {
+        REQUIRE_THROWS_AS(map.at(4), kstd::tests::os_panic);
+      }
+    }
+  }
+
+  GIVEN("A const populated Flat Map")
+  {
+    auto map_builder = kstd::flat_map<int, int>{};
+    map_builder.emplace(1, 10);
+    map_builder.emplace(2, 20);
+    auto const map = map_builder;
+
+    WHEN("accessing an existing element with const at()")
+    {
+      auto const & val = map.at(2);
+
+      THEN("it returns a const reference to the mapped value")
+      {
+        REQUIRE(val == 20);
+      }
+    }
+
+    WHEN("accessing a non-existent element with const at()")
+    {
+      THEN("it panics")
+      {
+        REQUIRE_THROWS_AS(map.at(4), kstd::tests::os_panic);
+      }
+    }
+  }
+}
+
+SCENARIO("Flat Map iterators", "[flat_map]")
+{
+  GIVEN("A populated Flat Map")
+  {
+    auto map = kstd::flat_map<int, int>{};
+    map.emplace(1, 10);
+    map.emplace(2, 20);
+    map.emplace(3, 30);
+
+    WHEN("using forward iterators")
+    {
+      THEN("they navigate the elements in the correct forward order")
+      {
+        auto it = map.begin();
+        REQUIRE(it != map.end());
+        REQUIRE((*it).first == 1);
+
+        ++it;
+        REQUIRE(it != map.end());
+        REQUIRE((*it).first == 2);
+
+        ++it;
+        REQUIRE(it != map.end());
+        REQUIRE((*it).first == 3);
+
+        ++it;
+        REQUIRE(it == map.end());
+      }
+
+      THEN("const forward iterators provide correct access")
+      {
+        auto it = map.cbegin();
+        REQUIRE(it != map.cend());
+        REQUIRE((*it).first == 1);
+
+        ++it;
+        REQUIRE(it != map.cend());
+        REQUIRE((*it).first == 2);
+
+        ++it;
+        REQUIRE(it != map.cend());
+        REQUIRE((*it).first == 3);
+
+        ++it;
+        REQUIRE(it == map.cend());
+      }
+
+      THEN("assignment through the proxy modifies the mapped value")
+      {
+        auto it = map.begin();
+
+        *it = std::pair{1, 100};
+
+        REQUIRE(it->second == 100);
+        REQUIRE(map.at(1) == 100);
+      }
+
+      THEN("structured bindings evaluate correctly")
+      {
+        auto it = map.cbegin();
+
+        auto [key, value] = *it;
+
+        REQUIRE(key == 1);
+        REQUIRE(value == 10);
+
+        STATIC_REQUIRE(std::is_same_v<decltype(key), int const &>);
+        STATIC_REQUIRE(std::is_same_v<decltype(value), int const &>);
+      }
+    }
+
+    WHEN("using reverse iterators")
+    {
+      THEN("they navigate the elements in the correct reverse order")
+      {
+        auto it = map.rbegin();
+        REQUIRE(it != map.rend());
+        REQUIRE((*it).first == 3);
+
+        ++it;
+        REQUIRE(it != map.rend());
+        REQUIRE((*it).first == 2);
+
+        ++it;
+        REQUIRE(it != map.rend());
+        REQUIRE((*it).first == 1);
+
+        ++it;
+        REQUIRE(it == map.rend());
+      }
+
+      THEN("const reverse iterators provide correct access")
+      {
+        auto it = map.crbegin();
+        REQUIRE(it != map.crend());
+        REQUIRE((*it).first == 3);
+
+        ++it;
+        REQUIRE(it != map.crend());
+        REQUIRE((*it).first == 2);
+
+        ++it;
+        REQUIRE(it != map.crend());
+        REQUIRE((*it).first == 1);
+
+        ++it;
+        REQUIRE(it == map.crend());
+      }
+    }
+  }
+
+  GIVEN("an empty Flat Map")
+  {
+    auto map = kstd::flat_map<int, int>{};
+
+    WHEN("getting iterators")
+    {
+      THEN("begin() equals end() and cbegin() equals cend()")
+      {
+        REQUIRE(map.begin() == map.end());
+        REQUIRE(map.cbegin() == map.cend());
+      }
+
+      THEN("rbegin() equals rend() and crbegin() equals crend()")
+      {
+        REQUIRE(map.rbegin() == map.rend());
+        REQUIRE(map.crbegin() == map.crend());
+      }
+    }
+  }
+}
+
+SCENARIO("Flat Map heterogeneous element access", "[flat_map]")
+{
+  GIVEN("A populated Flat Map with a transparent comparator")
+  {
+    auto map = kstd::flat_map<int, int, std::less<void>>{};
+    map.emplace(1, 10);
+    map.emplace(2, 20);
+    map.emplace(3, 30);
+
+    WHEN("accessing an existing element with a different key type via at()")
+    {
+      long const key = 2L;
+      auto & val = map.at(key);
+
+      THEN("it returns a reference to the mapped value")
+      {
+        REQUIRE(val == 20);
+      }
+
+      THEN("the mapped value can be modified")
+      {
+        val = 200;
+        REQUIRE(map.at(2L) == 200);
+      }
+    }
+
+    WHEN("accessing a non-existent element with a different key type via at()")
+    {
+      long const key = 4L;
+      THEN("it panics")
+      {
+        REQUIRE_THROWS_AS(map.at(key), kstd::tests::os_panic);
+      }
+    }
+  }
+
+  GIVEN("A const populated Flat Map with a transparent comparator")
+  {
+    auto map_builder = kstd::flat_map<int, int, std::less<void>>{};
+    map_builder.emplace(1, 10);
+    map_builder.emplace(2, 20);
+    auto const map = map_builder;
+
+    WHEN("accessing an existing element with a different key type via const at()")
+    {
+      long const key = 2L;
+      auto const & val = map.at(key);
+
+      THEN("it returns a const reference to the mapped value")
+      {
+        REQUIRE(val == 20);
+      }
+    }
+
+    WHEN("accessing a non-existent element with a different key type via const at()")
+    {
+      long const key = 4L;
+      THEN("it panics")
+      {
+        REQUIRE_THROWS_AS(map.at(key), kstd::tests::os_panic);
+      }
+    }
+  }
+}