kstd: add basic format and format_to tests

4 files changed, 140 insertions, 3 deletions

diff --git a/libs/kstd/CMakeLists.txt b/libs/kstd/CMakeLists.txt
index f7c771b..ced3138 100644
--- a/libs/kstd/CMakeLists.txt
+++ b/libs/kstd/CMakeLists.txt
@@ -44,6 +44,7 @@ if(CMAKE_CROSSCOMPILING)
 else()
     add_executable("kstd_tests"
         "tests/src/flat_map.cpp"
+        "tests/src/format.cpp"
         "tests/src/vector.cpp"
         "tests/src/observer_ptr.cpp"
         "tests/src/os_panic.cpp"
diff --git a/libs/kstd/include/kstd/bits/format/vformat.hpp b/libs/kstd/include/kstd/bits/format/vformat.hpp
index 69c7f33..4fec7dd 100644
--- a/libs/kstd/include/kstd/bits/format/vformat.hpp
+++ b/libs/kstd/include/kstd/bits/format/vformat.hpp
@@ -52,7 +52,7 @@ namespace kstd
 
       auto push(std::string_view text) -> void override
       {
-        m_output = std::ranges::copy(text, m_output);
+        m_output = std::ranges::copy(text, m_output).out;
       }
 
       auto push(char character) -> void override
@@ -75,7 +75,7 @@ namespace kstd
   auto format(format_string<std::type_identity_t<ArgumentTypes>...> format, ArgumentTypes &&... args) -> string
   {
     auto buffer = bits::format::string_writer{};
-    bits::format::vformat_to(buffer, format.str_view, std::forward<ArgumentTypes>(args)...);
+    bits::format::vformat_to(buffer, format.str_view, make_format_args(std::forward<ArgumentTypes>(args)...).args);
     return buffer.release();
   }
 
@@ -90,7 +90,7 @@ namespace kstd
                  ArgumentTypes &&... args) -> Output
   {
     auto buffer = bits::format::iterator_writer{iterator};
-    bits::format::vformat_to(buffer, format.str_view, std::forward<ArgumentTypes>(args)...);
+    bits::format::vformat_to(buffer, format.str_view, make_format_args(std::forward<ArgumentTypes>(args)...).args);
     return buffer.iterator();
   }
 
diff --git a/libs/kstd/include/kstd/string b/libs/kstd/include/kstd/string
index 4ce19ce..58c4a08 100644
--- a/libs/kstd/include/kstd/string
+++ b/libs/kstd/include/kstd/string
@@ -347,6 +347,26 @@ namespace kstd
     return !(lhs == rhs);
   }
 
+  [[nodiscard]] constexpr auto inline operator==(string const & lhs, char const * rhs) -> bool
+  {
+    return lhs.view() == std::string_view{rhs};
+  }
+
+  [[nodiscard]] constexpr auto inline operator!=(string const & lhs, char const * rhs) -> bool
+  {
+    return !(lhs == rhs);
+  }
+
+  [[nodiscard]] constexpr auto inline operator==(char const * lhs, string const & rhs) -> bool
+  {
+    return std::string_view{lhs} == rhs.view();
+  }
+
+  [[nodiscard]] constexpr auto inline operator!=(char const * lhs, string const & rhs) -> bool
+  {
+    return !(lhs == rhs);
+  }
+
   template<>
   struct formatter<string> : formatter<std::string_view>
   {
diff --git a/libs/kstd/tests/src/format.cpp b/libs/kstd/tests/src/format.cpp
new file mode 100644
index 0000000..4915e50
--- /dev/null
+++ b/libs/kstd/tests/src/format.cpp
@@ -0,0 +1,116 @@
+#include <kstd/flat_map>
+#include <kstd/format>
+#include <kstd/tests/os_panic.hpp>
+
+#include <catch2/catch_test_macros.hpp>
+
+#include <iterator>
+#include <sstream>
+
+SCENARIO("Formatting to a new string", "[format]")
+{
+  GIVEN("a format string without any placeholders")
+  {
+    auto const & fmt = "This is a test";
+
+    WHEN("calling format with without any arguments.")
+    {
+      auto result = kstd::format(fmt);
+
+      THEN("the result is the unmodified string")
+      {
+        REQUIRE(result == "This is a test");
+      }
+    }
+
+    WHEN("calling format with additional arguments")
+    {
+      auto result = kstd::format(fmt, 1, 2, 3);
+
+      THEN("the result is the unmodified string")
+      {
+        REQUIRE(result == "This is a test");
+      }
+    }
+  }
+
+  GIVEN("a format string with placeholders")
+  {
+    auto const & fmt = "Here are some placeholders: {} {} {}";
+
+    WHEN("calling format with the same number of arguments as there are placeholders")
+    {
+      auto result = kstd::format(fmt, 1, true, -100);
+
+      THEN("the result is the formatted string")
+      {
+        REQUIRE(result == "Here are some placeholders: 1 true -100");
+      }
+    }
+
+    WHEN("calling format with too many arguments")
+    {
+      auto result = kstd::format(fmt, 2, false, -200, 4, 5, 6);
+
+      THEN("the result is the formatted string")
+      {
+        REQUIRE(result == "Here are some placeholders: 2 false -200");
+      }
+    }
+  }
+}
+
+SCENARIO("Formatting to an output iterator", "[format]")
+{
+  auto buffer = std::ostringstream{};
+
+  GIVEN("a format string without any placeholders")
+  {
+    auto const & fmt = "This is a test";
+
+    WHEN("calling format with without any arguments.")
+    {
+      kstd::format_to(std::ostream_iterator<char>{buffer}, fmt);
+
+      THEN("the unmodified string is written to the iterator")
+      {
+        REQUIRE(buffer.str() == "This is a test");
+      }
+    }
+
+    WHEN("calling format with additional arguments")
+    {
+      kstd::format_to(std::ostream_iterator<char>{buffer}, fmt, 1, 2, 3);
+
+      THEN("the unmodified string is written to the iterator")
+      {
+        REQUIRE(buffer.str() == "This is a test");
+      }
+    }
+  }
+
+  GIVEN("a format string with placeholders")
+  {
+    auto const & fmt = "Here are some placeholders: {} {} {}";
+
+    WHEN("calling format with the same number of arguments as there are placeholders")
+    {
+      kstd::format_to(std::ostream_iterator<char>{buffer}, fmt, 1, true, -100);
+
+      THEN("the formatted string is written to the iterator")
+      {
+        REQUIRE(buffer.str() == "Here are some placeholders: 1 true -100");
+      }
+    }
+
+    WHEN("calling format with too many arguments")
+    {
+      kstd::format_to(std::ostream_iterator<char>{buffer}, fmt, 2, false, -200, 4, 5, 6);
+
+      THEN("the formatted string is written to the iterator")
+      {
+        REQUIRE(buffer.str() == "Here are some placeholders: 2 false -200");
+      }
+    }
+  }
+}
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