Add dry-run for syncthingctl edit

cli/application.cpp

@@ -678,6 +678,11 @@ void Application::editConfig(const ArgumentOccurrence &)
         cerr << Phrases::Error << "New config object seems empty." << Phrases::EndFlush;
         return;
     }
+    // handle "dry-run" case
+    if (m_args.dryRun.isPresent()) {
+        cout << newConfig.data() << flush;
+        return;
+    }
 
     // post new config
     using namespace TestUtilities;

cli/args.cpp

@@ -22,6 +22,7 @@ Args::Args()
     , rescanPwd("rescan", 'r', "rescans the current working directory")
     , pausePwd("pause", 'p', "pauses the current working directory")
     , resumePwd("resume", '\0', "resumes the current working directory")
+    , dryRun("dry-run", '\0', "writes the altered configuration to stdout instead of posting it to Syncthing")
     , dir("dir", 'd', "specifies a directory by ID", { "ID" })
     , dev("dev", '\0', "specifies a device by ID or name", { "ID/name" })
     , allDirs("all-dirs", '\0', "applies the operation for all directories")
@@ -47,7 +48,7 @@ Args::Args()
     waitForIdle.setExample(PROJECT_NAME " wait-for-idle --timeout 1800000 --at-least 5000 && systemctl poweroff\n" PROJECT_NAME
                                         " wait-for-idle --dir dir1 --dir dir2 --dev dev1 --dev dev2 --at-least 5000");
     pwd.setSubArguments({ &statusPwd, &rescanPwd, &pausePwd, &resumePwd });
-    edit.setSubArguments({ &editor });
+    edit.setSubArguments({ &editor, &dryRun });
 
     rescan.setValueNames({ "dir ID" });
     rescan.setRequiredValueCount(Argument::varValueCount);

cli/args.h

@@ -14,6 +14,7 @@ struct Args {
     NoColorArgument noColor;
     OperationArgument status, log, stop, restart, rescan, rescanAll, pause, resume, waitForIdle, pwd, cat, edit;
     OperationArgument statusPwd, rescanPwd, pausePwd, resumePwd;
+    ConfigValueArgument dryRun;
     ConfigValueArgument dir, dev, allDirs, allDevs;
     ConfigValueArgument atLeast, timeout;
     ConfigValueArgument editor;