Add condition field to SimpleMessage

The LOOT application uses a SimpleMessage with a condition just as often as without it, so this simplifies that usage.

include/loot/struct/simple_message.h

@@ -40,6 +40,9 @@ struct SimpleMessage {
    * [GitHub Flavored Markdown](https://help.github.com/articles/github-flavored-markdown).
    */
   std::string text;
+
+  /** @brief The message's condition string. */
+  std::string condition;
 };
 }
 

src/api/metadata/message.cpp

@@ -80,6 +80,7 @@ SimpleMessage Message::ToSimpleMessage(const std::string& language) const {
   simpleMessage.type = GetType();
   simpleMessage.language = content.GetLanguage();
   simpleMessage.text = content.GetText();
+  simpleMessage.condition = GetCondition();
 
   return simpleMessage;
 }

src/tests/api/internals/metadata/message_test.h

@@ -143,13 +143,14 @@ TEST_P(MessageTest, toSimpleMessageShouldSelectTextAndLanguageUsingGetContent) {
     MessageContent("content1", german),
     MessageContent("content2"),
     MessageContent("content3", french),
-  }));
+  }), "condition1");
 
   SimpleMessage simpleMessage = message.ToSimpleMessage(french);
 
   EXPECT_EQ(MessageType::warn, simpleMessage.type);
   EXPECT_EQ("content3", simpleMessage.text);
   EXPECT_EQ(french, simpleMessage.language);
+  EXPECT_EQ("condition1", simpleMessage.condition);
 }
 
 TEST_P(MessageTest, emittingAsYamlShouldOutputNoteMessageTypeCorrectly) {