Return C++17 std::optional<T> for unexceptionally-fallible functions

- DatabaseInterface::GetPluginMetadata()
- DatabaseInterface::GetPluginUserMetadata()
- GameInterface::GetPlugin()
- PluginInterface::GetVersion()
- PluginInterface::GetCRC()

include/loot/database_interface.h

@@ -24,6 +24,7 @@
 #ifndef LOOT_DATABASE_INTERFACE
 #define LOOT_DATABASE_INTERFACE
 
+#include <optional>
 #include <string>
 #include <vector>
 
@@ -226,11 +227,10 @@ public:
    *         If true, any metadata conditions are evaluated before the metadata
    *         is returned, otherwise unevaluated metadata is returned. Evaluating
    *         plugin metadata conditions does not clear the condition cache.
-   *  @returns A PluginMetadata object containing all the plugin's metadata.
-   *           If the plugin has no metadata, PluginMetadata.IsNameOnly()
-   *           will return true.
+   *  @returns If the plugin has metadata, an optional containing that metadata,
+   *           otherwise an optional containing no value.
    */
-  virtual PluginMetadata GetPluginMetadata(
+  virtual std::optional<PluginMetadata> GetPluginMetadata(
       const std::string& plugin,
       bool includeUserMetadata = true,
       bool evaluateConditions = false) const = 0;
@@ -243,11 +243,10 @@ public:
    *         If true, any metadata conditions are evaluated before the metadata
    *         is returned, otherwise unevaluated metadata is returned. Evaluating
    *         plugin metadata conditions does not clear the condition cache.
-   *  @returns A PluginMetadata object containing the plugin's user-added
-   *           metadata. If the plugin has no metadata,
-   *           PluginMetadata.IsNameOnly() will return true.
+   *  @returns If the plugin has user-added metadata, an optional containing
+   *           that metadata, otherwise an optional containing no value.
    */
-  virtual PluginMetadata GetPluginUserMetadata(
+  virtual std::optional<PluginMetadata> GetPluginUserMetadata(
       const std::string& plugin,
       bool evaluateConditions = false) const = 0;
 

include/loot/game_interface.h

@@ -24,6 +24,8 @@
 #ifndef LOOT_GAME_INTERFACE
 #define LOOT_GAME_INTERFACE
 
+#include <optional>
+
 #include "loot/database_interface.h"
 #include "loot/plugin_interface.h"
 
@@ -77,14 +79,13 @@ public:
 
   /**
    * @brief Get data for a loaded plugin.
-   * @details Throws an exception if the given plugin has not been loaded.
    * @param  pluginName
    *         The filename of the plugin to get data for.
-   * @returns A const PluginInterface reference. The reference remains valid
-   *          until the ``LoadPlugins()`` or ``SortPlugins()`` functions are
-   *          next called or this GameInterface is destroyed.
+   * @returns If the plugin has been loaded, an optional containing a pointer to
+   *          an implementation of PluginInterface for that plugin, otherwise an
+   *          optional containing no value.
    */
-  virtual std::shared_ptr<const PluginInterface> GetPlugin(
+  virtual std::optional<std::shared_ptr<const PluginInterface>> GetPlugin(
       const std::string& pluginName) const = 0;
 
   /**

include/loot/plugin_interface.h

@@ -25,6 +25,7 @@
 #define LOOT_PLUGIN_INTERFACE
 
 #include <cstdint>
+#include <optional>
 #include <set>
 #include <string>
 #include <vector>
@@ -53,12 +54,13 @@ public:
   /**
    * Get the plugin's version number from its description field.
    *
-   * If no version number is found in the description field, an empty string is
-   * returned. The description field parsing may fail to extract the version
-   * number correctly, though it functions correctly in all known cases.
-   * @return A string containing a version number, or an empty string.
+   * The description field may not contain a version number, or LOOT may be
+   * unable to detect it. The description field parsing may fail to extract the
+   * version number correctly, though it functions correctly in all known cases.
+   * @return An optional containing a version string if one is found, otherwise
+   *         an optional containing no value.
    */
-  virtual std::string GetVersion() const = 0;
+  virtual std::optional<std::string> GetVersion() const = 0;
 
   /**
    * Get the plugin's masters.
@@ -75,10 +77,10 @@ public:
 
   /**
    * Get the plugin's CRC-32 checksum.
-   * @return The plugin's CRC-32 checksum if it has been fully read. If only the
-   *         plugin's header has been read, ``0`` will be returned.
+   * @return An optional containing the plugin's CRC-32 checksum if the plugin
+   *         has been fully loaded, otherwise an optional containing no value.
    */
-  virtual uint32_t GetCRC() const = 0;
+  virtual std::optional<uint32_t> GetCRC() const = 0;
 
   /**
    * Check if the plugin's master flag is set.

src/api/api_database.cpp

@@ -199,29 +199,34 @@ void ApiDatabase::SetUserGroups(const std::unordered_set<Group>& groups) {
   userlist_.SetGroups(groups);
 }
 
-PluginMetadata ApiDatabase::GetPluginMetadata(const std::string& plugin,
+std::optional<PluginMetadata> ApiDatabase::GetPluginMetadata(const std::string& plugin,
                                               bool includeUserMetadata,
                                               bool evaluateConditions) const {
-  PluginMetadata metadata = masterlist_.FindPlugin(plugin);
+  auto metadata = masterlist_.FindPlugin(plugin);
 
   if (includeUserMetadata) {
-    metadata.MergeMetadata(userlist_.FindPlugin(plugin));
+    auto userMetadata = userlist_.FindPlugin(plugin);
+    if (metadata && userMetadata) {
+      metadata.value().MergeMetadata(userMetadata.value());
+    } else if (userMetadata) {
+      metadata = userMetadata;
+    }
   }
 
-  if (evaluateConditions) {
-    return conditionEvaluator_.evaluateAll(metadata);
+  if (evaluateConditions && metadata) {
+    return conditionEvaluator_.evaluateAll(metadata.value());
   }
 
   return metadata;
 }
 
-PluginMetadata ApiDatabase::GetPluginUserMetadata(
+std::optional<PluginMetadata> ApiDatabase::GetPluginUserMetadata(
     const std::string& plugin,
     bool evaluateConditions) const {
-  PluginMetadata metadata = userlist_.FindPlugin(plugin);
+  auto metadata = userlist_.FindPlugin(plugin);
 
-  if (evaluateConditions) {
-    return conditionEvaluator_.evaluateAll(metadata);
+  if (evaluateConditions && metadata) {
+    return conditionEvaluator_.evaluateAll(metadata.value());
   }
 
   return metadata;

src/api/api_database.h

@@ -72,12 +72,14 @@ struct ApiDatabase : public DatabaseInterface {
   std::unordered_set<Group> GetUserGroups() const;
   void SetUserGroups(const std::unordered_set<Group>& groups);
 
-  PluginMetadata GetPluginMetadata(const std::string& plugin,
-                                   bool includeUserMetadata = true,
-                                   bool evaluateConditions = false) const;
+  std::optional<PluginMetadata> GetPluginMetadata(
+      const std::string& plugin,
+      bool includeUserMetadata = true,
+      bool evaluateConditions = false) const;
 
-  PluginMetadata GetPluginUserMetadata(const std::string& plugin,
-                                       bool evaluateConditions = false) const;
+  std::optional<PluginMetadata> GetPluginUserMetadata(
+      const std::string& plugin,
+      bool evaluateConditions = false) const;
 
   void SetPluginUserMetadata(const PluginMetadata& pluginMetadata);
 

src/api/game/game.cpp

@@ -192,10 +192,9 @@ void Game::LoadPlugins(const std::vector<std::string>& plugins,
   }
 }
 
-std::shared_ptr<const PluginInterface> Game::GetPlugin(
+std::optional<std::shared_ptr<const PluginInterface>> Game::GetPlugin(
     const std::string& pluginName) const {
-  return std::static_pointer_cast<const PluginInterface>(
-      cache_->GetPlugin(pluginName));
+  return cache_->GetPlugin(pluginName);
 }
 
 std::set<std::shared_ptr<const PluginInterface>> Game::GetLoadedPlugins()
@@ -226,13 +225,14 @@ void Game::LoadCurrentLoadOrderState() {
   loadOrderHandler_->LoadCurrentState();
 }
 
-bool Game::IsPluginActive(const std::string& plugin) const {
-  try {
-    return std::static_pointer_cast<const Plugin>(GetPlugin(plugin))
-        ->IsActive();
-  } catch (...) {
-    return loadOrderHandler_->IsPluginActive(plugin);
+bool Game::IsPluginActive(const std::string& pluginName) const {
+  auto plugin = cache_->GetPlugin(pluginName);
+
+  if (plugin) {
+    return plugin.value()->IsActive();
   }
+
+  return loadOrderHandler_->IsPluginActive(pluginName);
 }
 
 std::vector<std::string> Game::GetLoadOrder() const {

src/api/game/game.h

@@ -59,7 +59,8 @@ public:
   void LoadPlugins(const std::vector<std::string>& plugins,
                    bool loadHeadersOnly);
 
-  std::shared_ptr<const PluginInterface> GetPlugin(
+  std::optional<std::shared_ptr<const PluginInterface>>
+  GetPlugin(
       const std::string& pluginName) const;
 
   std::set<std::shared_ptr<const PluginInterface>> GetLoadedPlugins() const;

src/api/game/game_cache.cpp

@@ -97,13 +97,13 @@ std::set<std::shared_ptr<const Plugin>> GameCache::GetPlugins() const {
   return output;
 }
 
-std::shared_ptr<const Plugin> GameCache::GetPlugin(
+std::optional<std::shared_ptr<const Plugin>> GameCache::GetPlugin(
     const std::string& pluginName) const {
   auto it = plugins_.find(to_lower(pluginName));
   if (it != end(plugins_))
     return it->second;
 
-  throw std::invalid_argument("No plugin \"" + pluginName + "\" exists.");
+  return std::nullopt;
 }
 
 void GameCache::AddPlugin(const Plugin&& plugin) {

src/api/game/game_cache.h

@@ -47,7 +47,8 @@ public:
   void CacheCrc(const std::string& file, uint32_t crc);
 
   std::set<std::shared_ptr<const Plugin>> GetPlugins() const;
-  std::shared_ptr<const Plugin> GetPlugin(const std::string& pluginName) const;
+  std::optional<std::shared_ptr<const Plugin>> GetPlugin(
+      const std::string& pluginName) const;
   void AddPlugin(const Plugin&& plugin);
 
   std::set<boost::filesystem::path> GetArchivePaths() const;

src/api/metadata/condition_evaluator.cpp

@@ -156,19 +156,17 @@ bool ConditionEvaluator::fileExists(const std::string& filePath) const {
 
   // Try first checking the plugin cache, as most file entries are
   // for plugins.
-  try {
-    // GetPlugin throws if it can't find an entry.
-    gameCache_->GetPlugin(filePath);
-
+  auto plugin = gameCache_->GetPlugin(filePath);
+  if (plugin) {
     return true;
-  } catch (...) {
-    // Not a loaded plugin, check the filesystem.
-    if (hasPluginFileExtension(filePath, gameType_))
-      return boost::filesystem::exists(dataPath_ / filePath) ||
-             boost::filesystem::exists(dataPath_ / (filePath + ".ghost"));
-    else
-      return boost::filesystem::exists(dataPath_ / filePath);
   }
+
+  // Not a loaded plugin, check the filesystem.
+  if (hasPluginFileExtension(filePath, gameType_))
+    return boost::filesystem::exists(dataPath_ / filePath) ||
+            boost::filesystem::exists(dataPath_ / (filePath + ".ghost"));
+  else
+    return boost::filesystem::exists(dataPath_ / filePath);
 }
 
 bool ConditionEvaluator::regexMatchExists(
@@ -412,19 +410,22 @@ Version ConditionEvaluator::getVersion(const std::string& filePath) const {
     // If the file is a plugin, its version needs to be extracted
     // from its description field. Try getting an entry from the
     // plugin cache.
-    try {
-      return Version(gameCache_->GetPlugin(filePath)->GetVersion());
-    } catch (...) {
-      // The file wasn't in the plugin cache, load it as a plugin
-      // if it appears to be valid, otherwise treat it as a non
-      // plugin file.
-      if (Plugin::IsValid(filePath, gameType_, dataPath_))
-        return Version(
-            Plugin(gameType_, dataPath_, gameCache_, loadOrderHandler_, filePath, true)
-                .GetVersion());
 
-      return Version(dataPath_ / filePath);
+    auto plugin = gameCache_->GetPlugin(filePath);
+    if (plugin) {
+      return Version(plugin.value()->GetVersion().value_or(""));
     }
+
+    // The file wasn't in the plugin cache, load it as a plugin
+    // if it appears to be valid, otherwise treat it as a non
+    // plugin file.
+    if (Plugin::IsValid(filePath, gameType_, dataPath_))
+      return Version(
+          Plugin(gameType_, dataPath_, gameCache_, loadOrderHandler_, filePath, true)
+              .GetVersion()
+              .value_or(""));
+
+    return Version(dataPath_ / filePath);
   }
 }
 bool ConditionEvaluator::shouldParseOnly() const {
@@ -445,9 +446,9 @@ uint32_t ConditionEvaluator::getCrc(const std::string & file) const {
   }
 
   // Get the CRC from the game plugin cache if possible.
-  try {
-    crc = gameCache_->GetPlugin(file)->GetCRC();
-  } catch (...) {
+  auto plugin = gameCache_->GetPlugin(file);
+  if (plugin) {
+    crc = plugin.value()->GetCRC().value_or(0);
   }
 
   // Otherwise calculate it from the file.

src/api/metadata_list.cpp

@@ -143,8 +143,9 @@ void MetadataList::SetGroups(const std::unordered_set<Group>& groups) {
 }
 
 // Merges multiple matching regex entries if any are found.
-PluginMetadata MetadataList::FindPlugin(const PluginMetadata& plugin) const {
-  PluginMetadata match(plugin.GetName());
+std::optional<PluginMetadata> MetadataList::FindPlugin(
+    const std::string& plugin) const {
+  PluginMetadata match(plugin);
 
   auto it = plugins_.find(plugin);
 
@@ -159,6 +160,10 @@ PluginMetadata MetadataList::FindPlugin(const PluginMetadata& plugin) const {
     regIt = find(++regIt, regexPlugins_.end(), plugin);
   }
 
+  if (match.HasNameOnly()) {
+    return std::nullopt;
+  }
+
   return match;
 }
 

src/api/metadata_list.h

@@ -25,6 +25,7 @@
 #ifndef LOOT_API_METADATA_LIST
 #define LOOT_API_METADATA_LIST
 
+#include <optional>
 #include <string>
 #include <unordered_set>
 #include <vector>
@@ -32,8 +33,8 @@
 #include <boost/filesystem.hpp>
 
 #include "api/metadata/condition_evaluator.h"
-#include "loot/metadata/plugin_metadata.h"
 #include "loot/metadata/group.h"
+#include "loot/metadata/plugin_metadata.h"
 
 namespace loot {
 class MetadataList {
@@ -50,7 +51,7 @@ public:
   void SetGroups(const std::unordered_set<Group>& groups);
 
   // Merges multiple matching regex entries if any are found.
-  PluginMetadata FindPlugin(const PluginMetadata& plugin) const;
+  std::optional<PluginMetadata> FindPlugin(const std::string& plugin) const;
   void AddPlugin(const PluginMetadata& plugin);
 
   // Doesn't erase matching regex entries, because they might also

src/api/plugin.cpp

@@ -51,7 +51,6 @@ Plugin::Plugin(const GameType gameType,
     isEmpty_(true),
     isActive_(false),
     loadsArchive_(false),
-    crc_(0),
     numOverrideRecords_(0) {
   auto logger = getLogger();
 
@@ -139,8 +138,13 @@ std::string Plugin::GetLowercasedName() const {
   return boost::locale::to_lower(name_);
 }
 
-std::string Plugin::GetVersion() const {
-  return Version(GetDescription()).AsString();
+std::optional<std::string> Plugin::GetVersion() const {
+  std::string version = Version(GetDescription()).AsString();
+  if (version.empty()) {
+    return std::nullopt;
+  }
+
+  return version;
 }
 
 std::vector<std::string> Plugin::GetMasters() const {
@@ -160,7 +164,7 @@ std::vector<std::string> Plugin::GetMasters() const {
 
 std::set<Tag> Plugin::GetBashTags() const { return tags_; }
 
-uint32_t Plugin::GetCRC() const { return crc_; }
+std::optional<uint32_t> Plugin::GetCRC() const { return crc_; }
 
 bool Plugin::IsMaster() const {
   bool isMaster;

src/api/plugin.h

@@ -52,10 +52,10 @@ public:
 
   std::string GetName() const;
   std::string GetLowercasedName() const;
-  std::string GetVersion() const;
+  std::optional<std::string> GetVersion() const;
   std::vector<std::string> GetMasters() const;
   std::set<Tag> GetBashTags() const;
-  uint32_t GetCRC() const;
+  std::optional<uint32_t> GetCRC() const;
 
   bool IsMaster() const;
   bool IsLightMaster() const;
@@ -94,8 +94,8 @@ private:
   bool isActive_;
   bool loadsArchive_;
   const std::string name_;
-  std::string version_;  // Obtained from description field.
-  uint32_t crc_;
+  std::optional<std::string> version_;  // Obtained from description field.
+  std::optional<uint32_t> crc_;
   std::set<Tag> tags_;
 
   // Useful caches.

src/api/sorting/plugin_sorter.cpp

@@ -210,7 +210,7 @@ void PluginSorter::AddPluginVertices(Game& game) {
     }
 
     auto metadata =
-        game.GetDatabase()->GetPluginMetadata(plugin->GetName(), true, true);
+        game.GetDatabase()->GetPluginMetadata(plugin->GetName(), true, true).value_or(PluginMetadata(plugin->GetName()));
 
     auto groupIt = groupPlugins.find(metadata.GetGroup());
     if (groupIt == groupPlugins.end()) {

src/tests/api/interface/database_interface_test.h

@@ -544,10 +544,8 @@ TEST_P(
 
 TEST_P(
     DatabaseInterfaceTest,
-    getPluginMetadataShouldReturnAnEmptyPluginMetadataObjectIfThePluginHasNoMetadata) {
-  auto metadata = db_->GetPluginMetadata(blankEsm);
-
-  EXPECT_TRUE(metadata.HasNameOnly());
+    getPluginMetadataShouldReturnAnEmptyOptionalIfThePluginHasNoMetadata) {
+  EXPECT_FALSE(db_->GetPluginMetadata(blankEsm));
 }
 
 TEST_P(
@@ -558,7 +556,7 @@ TEST_P(
   ASSERT_NO_THROW(
       db_->LoadLists(masterlistPath.string(), userlistPath_.string()));
 
-  auto metadata = db_->GetPluginMetadata(blankEsm, true);
+  auto metadata = db_->GetPluginMetadata(blankEsm, true).value();
 
   std::set<File> expectedLoadAfter({
       File(masterFile),
@@ -575,7 +573,7 @@ TEST_P(
   ASSERT_NO_THROW(
       db_->LoadLists(masterlistPath.string(), userlistPath_.string()));
 
-  auto metadata = db_->GetPluginMetadata(blankEsm, false);
+  auto metadata = db_->GetPluginMetadata(blankEsm, false).value();
 
   std::set<File> expectedLoadAfter({
       File(masterFile),
@@ -589,7 +587,7 @@ TEST_P(
   ASSERT_NO_THROW(GenerateMasterlist());
   ASSERT_NO_THROW(db_->LoadLists(masterlistPath.string(), ""));
 
-  auto metadata = db_->GetPluginMetadata(blankEsm, false, true);
+  auto metadata = db_->GetPluginMetadata(blankEsm, false, true).value();
 
   EXPECT_TRUE(metadata.GetMessages().empty());
 }
@@ -602,9 +600,7 @@ TEST_P(
   ASSERT_NO_THROW(
       db_->LoadLists(masterlistPath.string(), userlistPath_.string()));
 
-  auto metadata = db_->GetPluginUserMetadata(blankDifferentEsm);
-
-  EXPECT_TRUE(metadata.HasNameOnly());
+  EXPECT_FALSE(db_->GetPluginUserMetadata(blankDifferentEsm));
 }
 
 TEST_P(DatabaseInterfaceTest,
@@ -614,7 +610,7 @@ TEST_P(DatabaseInterfaceTest,
   ASSERT_NO_THROW(
       db_->LoadLists(masterlistPath.string(), userlistPath_.string()));
 
-  auto metadata = db_->GetPluginUserMetadata(blankEsm);
+  auto metadata = db_->GetPluginUserMetadata(blankEsm).value();
 
   std::set<File> expectedLoadAfter({
       File(blankDifferentEsm),
@@ -630,7 +626,7 @@ TEST_P(
   ASSERT_NO_THROW(
       db_->LoadLists(masterlistPath.string(), userlistPath_.string()));
 
-  auto metadata = db_->GetPluginMetadata(blankEsm, false, true);
+  auto metadata = db_->GetPluginMetadata(blankEsm, false, true).value();
 
   EXPECT_TRUE(metadata.GetMessages().empty());
 }
@@ -648,7 +644,7 @@ TEST_P(
 
   db_->SetPluginUserMetadata(newMetadata);
 
-  auto metadata = db_->GetPluginUserMetadata(blankDifferentEsp);
+  auto metadata = db_->GetPluginUserMetadata(blankDifferentEsp).value();
 
   std::set<File> expectedLoadAfter({
       File(blankDifferentEsm),
@@ -669,7 +665,7 @@ TEST_P(DatabaseInterfaceTest,
 
   db_->SetPluginUserMetadata(newMetadata);
 
-  auto metadata = db_->GetPluginMetadata(blankEsm);
+  auto metadata = db_->GetPluginMetadata(blankEsm).value();
 
   std::set<File> expectedLoadAfter({
       File(masterFile),
@@ -686,8 +682,7 @@ TEST_P(DatabaseInterfaceTest,
 
   db_->DiscardPluginUserMetadata(blankEsm);
 
-  auto metadata = db_->GetPluginUserMetadata(blankEsm);
-  EXPECT_TRUE(metadata.HasNameOnly());
+  EXPECT_FALSE(db_->GetPluginUserMetadata(blankEsm));
 }
 
 TEST_P(
@@ -700,7 +695,7 @@ TEST_P(
 
   db_->DiscardPluginUserMetadata(blankEsm);
 
-  auto metadata = db_->GetPluginMetadata(blankEsm);
+  auto metadata = db_->GetPluginMetadata(blankEsm).value();
 
   std::set<File> expectedLoadAfter({
       File(masterFile),
@@ -719,7 +714,7 @@ TEST_P(DatabaseInterfaceTest,
 
   auto metadata = db_->GetPluginUserMetadata(blankDifferentEsp);
 
-  EXPECT_FALSE(metadata.HasNameOnly());
+  EXPECT_TRUE(metadata);
 }
 
 TEST_P(DatabaseInterfaceTest,
@@ -770,13 +765,10 @@ TEST_P(
 
   db_->DiscardAllUserMetadata();
 
-  auto metadata = db_->GetPluginUserMetadata(blankEsm);
-  EXPECT_TRUE(metadata.HasNameOnly());
+  EXPECT_FALSE(db_->GetPluginUserMetadata(blankEsm));
+  EXPECT_FALSE(db_->GetPluginUserMetadata(blankDifferentEsp));
 
-  metadata = db_->GetPluginUserMetadata(blankDifferentEsp);
-  EXPECT_TRUE(metadata.HasNameOnly());
-
-  metadata = db_->GetPluginMetadata(blankEsm);
+  auto metadata = db_->GetPluginMetadata(blankEsm).value();
 
   std::set<File> expectedLoadAfter({
       File(masterFile),

src/tests/api/interface/game_interface_test.h

@@ -89,11 +89,11 @@ TEST_P(
 
   // Check that one plugin's header has been read.
   ASSERT_NO_THROW(handle_->GetPlugin(masterFile));
-  auto plugin = handle_->GetPlugin(masterFile);
-  EXPECT_EQ("5.0", plugin->GetVersion());
+  auto plugin = handle_->GetPlugin(masterFile).value();
+  EXPECT_EQ("5.0", plugin->GetVersion().value());
 
   // Check that only the header has been read.
-  EXPECT_EQ(0, plugin->GetCRC());
+  EXPECT_FALSE(plugin->GetCRC());
 }
 
 TEST_P(GameInterfaceTest,
@@ -103,15 +103,15 @@ TEST_P(GameInterfaceTest,
 
   // Check that one plugin's header has been read.
   ASSERT_NO_THROW(handle_->GetPlugin(masterFile));
-  auto plugin = handle_->GetPlugin(masterFile);
-  EXPECT_EQ("5.0", plugin->GetVersion());
+  auto plugin = handle_->GetPlugin(masterFile).value();
+  EXPECT_EQ("5.0", plugin->GetVersion().value());
 
   // Check that not only the header has been read.
-  EXPECT_EQ(blankEsmCrc, plugin->GetCRC());
+  EXPECT_EQ(blankEsmCrc, plugin->GetCRC().value());
 }
 
-TEST_P(GameInterfaceTest, getPluginThatIsNotCachedShouldThrow) {
-  EXPECT_THROW(handle_->GetPlugin(blankEsm), std::invalid_argument);
+TEST_P(GameInterfaceTest, getPluginThatIsNotCachedShouldReturnAnEmptyOptional) {
+  EXPECT_FALSE(handle_->GetPlugin(blankEsm));
 }
 
 TEST_P(GameInterfaceTest,

src/tests/api/internals/game/game_cache_test.h

@@ -86,7 +86,7 @@ TEST_P(GameCacheTest, addingAPluginThatDoesNotExistShouldSucceed) {
                           game_.GetLoadOrderHandler(),
                           blankEsm,
                           true));
-  EXPECT_EQ(blankEsm, cache_.GetPlugin(blankEsm)->GetName());
+  EXPECT_EQ(blankEsm, cache_.GetPlugin(blankEsm).value()->GetName());
 }
 
 TEST_P(GameCacheTest,
@@ -97,7 +97,7 @@ TEST_P(GameCacheTest,
                           game_.GetLoadOrderHandler(),
                           blankEsm,
                           true));
-  EXPECT_EQ(0, cache_.GetPlugin(blankEsm)->GetCRC());
+  EXPECT_FALSE(cache_.GetPlugin(blankEsm).value()->GetCRC());
 
   cache_.AddPlugin(Plugin(game_.Type(),
                           game_.DataPath(),
@@ -105,11 +105,11 @@ TEST_P(GameCacheTest,
                           game_.GetLoadOrderHandler(),
                           blankEsm,
                           false));
-  EXPECT_EQ(blankEsmCrc, cache_.GetPlugin(blankEsm)->GetCRC());
+  EXPECT_EQ(blankEsmCrc, cache_.GetPlugin(blankEsm).value()->GetCRC().value());
 }
 
-TEST_P(GameCacheTest, gettingAPluginThatIsNotCachedShouldThrow) {
-  EXPECT_THROW(cache_.GetPlugin(blankEsm), std::invalid_argument);
+TEST_P(GameCacheTest, gettingAPluginThatIsNotCachedShouldReturnAnEmptyOptional) {
+  EXPECT_FALSE(cache_.GetPlugin(blankEsm));
 }
 
 TEST_P(GameCacheTest, gettingAPluginShouldBeCaseInsensitive) {
@@ -119,7 +119,7 @@ TEST_P(GameCacheTest, gettingAPluginShouldBeCaseInsensitive) {
                           game_.GetLoadOrderHandler(),
                           blankEsm,
                           true));
-  EXPECT_EQ(blankEsm, cache_.GetPlugin(blankEsm)->GetName());
+  EXPECT_EQ(blankEsm, cache_.GetPlugin(blankEsm).value()->GetName());
 }
 
 TEST_P(GameCacheTest,

src/tests/api/internals/game/game_test.h

@@ -108,11 +108,11 @@ TEST_P(
 
   // Check that one plugin's header has been read.
   ASSERT_NO_THROW(game.GetPlugin(masterFile));
-  auto plugin = game.GetPlugin(masterFile);
-  EXPECT_EQ("5.0", plugin->GetVersion());
+  auto plugin = game.GetPlugin(masterFile).value();
+  EXPECT_EQ("5.0", plugin->GetVersion().value());
 
   // Check that only the header has been read.
-  EXPECT_EQ(0, plugin->GetCRC());
+  EXPECT_FALSE(plugin->GetCRC());
 }
 
 TEST_P(GameTest, loadPluginsWithANonPluginShouldNotAddItToTheLoadedPlugins) {
@@ -149,11 +149,11 @@ TEST_P(GameTest,
 
   // Check that one plugin's header has been read.
   ASSERT_NO_THROW(game.GetPlugin(blankEsm));
-  auto plugin = game.GetPlugin(blankEsm);
-  EXPECT_EQ("5.0", plugin->GetVersion());
+  auto plugin = game.GetPlugin(blankEsm).value();
+  EXPECT_EQ("5.0", plugin->GetVersion().value());
 
   // Check that not only the header has been read.
-  EXPECT_EQ(blankEsmCrc, plugin->GetCRC());
+  EXPECT_EQ(blankEsmCrc, plugin->GetCRC().value());
 }
 
 TEST_P(GameTest,

src/tests/api/internals/metadata_list_test.h

@@ -280,13 +280,9 @@ TEST_P(MetadataListTest, setGroupsShouldReplaceExistingGroups) {
 
 TEST_P(
     MetadataListTest,
-    findPluginShouldReturnAnEmptyPluginObjectIfTheGivenPluginIsNotInTheMetadataList) {
+    findPluginShouldReturnAnEmptyOptionalIfTheGivenPluginIsNotInTheMetadataList) {
   MetadataList metadataList;
-  PluginMetadata plugin =
-      metadataList.FindPlugin(PluginMetadata(blankDifferentEsm));
-
-  EXPECT_EQ(blankDifferentEsm, plugin.GetName());
-  EXPECT_TRUE(plugin.HasNameOnly());
+  EXPECT_FALSE(metadataList.FindPlugin(blankDifferentEsm));
 }
 
 TEST_P(
@@ -296,7 +292,7 @@ TEST_P(
   ASSERT_NO_THROW(metadataList.Load(metadataPath));
 
   PluginMetadata plugin =
-      metadataList.FindPlugin(PluginMetadata(blankDifferentEsp));
+      metadataList.FindPlugin(blankDifferentEsp).value();
 
   EXPECT_EQ(blankDifferentEsp, plugin.GetName());
   EXPECT_EQ(std::set<File>({
@@ -312,14 +308,13 @@ TEST_P(
 TEST_P(MetadataListTest, addPluginShouldStoreGivenSpecificPluginMetadata) {
   MetadataList metadataList;
   ASSERT_NO_THROW(metadataList.Load(metadataPath));
-  ASSERT_TRUE(
-      metadataList.FindPlugin(PluginMetadata(blankDifferentEsm)).HasNameOnly());
+  ASSERT_FALSE(metadataList.FindPlugin(blankDifferentEsm));
 
   PluginMetadata plugin(blankDifferentEsm);
   plugin.SetGroup("group1");
   metadataList.AddPlugin(plugin);
 
-  plugin = metadataList.FindPlugin(plugin);
+  plugin = metadataList.FindPlugin(plugin.GetName()).value();
 
   EXPECT_EQ(blankDifferentEsm, plugin.GetName());
   EXPECT_EQ("group1", plugin.GetGroup());
@@ -333,7 +328,8 @@ TEST_P(MetadataListTest, addPluginShouldStoreGivenRegexPluginMetadata) {
   plugin.SetGroup("group1");
   metadataList.AddPlugin(plugin);
 
-  plugin = metadataList.FindPlugin(PluginMetadata(blankPluginDependentEsp));
+  plugin =
+      metadataList.FindPlugin(blankPluginDependentEsp).value();
 
   EXPECT_EQ("group1", plugin.GetGroup());
 }
@@ -342,9 +338,8 @@ TEST_P(MetadataListTest, addPluginShouldThrowIfAMatchingPluginAlreadyExists) {
   MetadataList metadataList;
   ASSERT_NO_THROW(metadataList.Load(metadataPath));
 
-  PluginMetadata plugin = metadataList.FindPlugin(PluginMetadata(blankEsm));
+  PluginMetadata plugin = metadataList.FindPlugin(blankEsm).value();
   ASSERT_EQ(blankEsm, plugin.GetName());
-  ASSERT_FALSE(plugin.HasNameOnly());
 
   EXPECT_THROW(metadataList.AddPlugin(PluginMetadata(blankEsm)),
                std::invalid_argument);
@@ -355,15 +350,13 @@ TEST_P(MetadataListTest,
   MetadataList metadataList;
   ASSERT_NO_THROW(metadataList.Load(metadataPath));
 
-  PluginMetadata plugin = metadataList.FindPlugin(PluginMetadata(blankEsp));
+  PluginMetadata plugin = metadataList.FindPlugin(blankEsp).value();
   ASSERT_EQ(blankEsp, plugin.GetName());
   ASSERT_FALSE(plugin.HasNameOnly());
 
   metadataList.ErasePlugin(plugin);
 
-  plugin = metadataList.FindPlugin(plugin);
-  EXPECT_EQ(blankEsp, plugin.GetName());
-  EXPECT_TRUE(plugin.HasNameOnly());
+  EXPECT_FALSE(metadataList.FindPlugin(plugin.GetName()));
 }
 
 TEST_P(
@@ -378,7 +371,7 @@ TEST_P(
   MetadataList metadataList;
   ASSERT_NO_THROW(metadataList.Load(metadataPath));
 
-  PluginMetadata plugin = metadataList.FindPlugin(PluginMetadata(blankEsm));
+  PluginMetadata plugin = metadataList.FindPlugin(blankEsm).value();
   ASSERT_EQ(
       std::vector<Message>({
           Message(MessageType::warn, "This is a warning."),
@@ -387,19 +380,19 @@ TEST_P(
       }),
       plugin.GetMessages());
 
-  plugin = metadataList.FindPlugin(PluginMetadata(blankEsp));
+  plugin = metadataList.FindPlugin(blankEsp).value();
   ASSERT_EQ(blankEsp, plugin.GetName());
   ASSERT_FALSE(plugin.HasNameOnly());
 
   EXPECT_NO_THROW(metadataList.EvalAllConditions(evaluator));
 
-  plugin = metadataList.FindPlugin(PluginMetadata(blankEsm));
+  plugin = metadataList.FindPlugin(blankEsm).value();
   EXPECT_EQ(std::vector<Message>({
                 Message(MessageType::warn, "This is a warning."),
             }),
             plugin.GetMessages());
 
-  plugin = metadataList.FindPlugin(PluginMetadata(blankEsp));
+  plugin = metadataList.FindPlugin(blankEsp).value();
   EXPECT_EQ(blankEsp, plugin.GetName());
   EXPECT_TRUE(plugin.GetDirtyInfo().empty());
 }