Don't accept empty game path in CreateGameHandle()

Add a new logging statement partially to have an easily testable
message and partly because knowing the unresolved paths could be
useful.

include/loot/api.h

@@ -111,10 +111,8 @@ LOOT_API void InitialiseLocale(const std::string& id = "");
  *  @param game
  *         A game code for which to create the handle.
  *  @param game_path
- *         The relative or absolute path to the game folder, or an empty string.
- *         If an empty string, the API will attempt to detect the data path of
- *         the specified game by searching for the game's main master file in a
- *         sibling Data folder and by searching for the game's Registry entry.
+ *         The relative or absolute path to the directory containing the
+ *         game's executable.
  *  @param game_local_path
  *         The relative or absolute path to the game's folder in
  *         `%%LOCALAPPDATA%` or an empty string. If an empty string, the API
@@ -125,7 +123,7 @@ LOOT_API void InitialiseLocale(const std::string& id = "");
  */
 LOOT_API std::shared_ptr<GameInterface> CreateGameHandle(
     const GameType game,
-    const std::string& game_path = "",
+    const std::string& game_path,
     const std::string& game_local_path = "");
 }
 

src/api/api.cpp

@@ -70,8 +70,14 @@ LOOT_API std::shared_ptr<GameInterface> CreateGameHandle(
     const GameType game,
     const std::string& gamePath,
     const std::string& gameLocalPath) {
+  auto logger = getLogger();
+  if (logger) {
+    logger->info("Attempting to create a game handle with game path \"{}\" "
+      "and local path \"{}\"", gamePath, gameLocalPath);
+  }
+
   const std::string resolvedGamePath = ResolvePath(gamePath);
-  if (!gamePath.empty() && !fs::is_directory(resolvedGamePath))
+  if (!fs::is_directory(resolvedGamePath))
     throw std::invalid_argument("Given game path \"" + gamePath +
                                 "\" does not resolve to a valid directory.");
 

src/api/game/game.h

@@ -37,7 +37,7 @@ namespace loot {
 class Game : public GameInterface {
 public:
   Game(const GameType gameType,
-       const boost::filesystem::path& gamePath = "",
+       const boost::filesystem::path& gamePath,
        const boost::filesystem::path& gameLocalDataPath = "");
 
   // Internal Methods //

src/tests/api/interface/main.cpp

@@ -51,10 +51,11 @@ TEST(SetLoggingCallback, shouldWriteMessagesToGivenCallback) {
   });
 
   try {
-    CreateGameHandle(GameType::tes4, "", "");
+    CreateGameHandle(GameType::tes4, "dummy");
   } catch (...) {
-    EXPECT_EQ("Initialising load order data for game of type 0 at: ",
-              loggedMessages);
+    EXPECT_EQ("Attempting to create a game handle with game path \"dummy\" "
+      "and local path \"\"",
+      loggedMessages);
 
     SetLoggingCallback([](LogLevel, const char *) {});
     return;