Play Solo & Test Server auto connect (#840)

When enabled, the `baseurl` of the session is written to
`workspace:SetAttribute("__Rojo_ConnectionUrl")` so that the test server
can connect to that session automatically.

This works for Play Solo and Local Test Server. It is marked
experimental for now (and disabled by default) since connecting during a
playtest session is... not polished. Rojo may overwrite things and cause
headaches. Further work can be done later.

plugin/src/App/init.lua

@@ -158,11 +158,29 @@ function App:init()
 			},
 		})
 	end
+
+	if self:isAutoConnectPlaytestServerAvailable() then
+		self:useRunningConnectionInfo()
+		self:startSession()
+	end
+	self.autoConnectPlaytestServerListener = Settings:onChanged("autoConnectPlaytestServer", function(enabled)
+		if enabled then
+			if self:isAutoConnectPlaytestServerWriteable() and self.serveSession ~= nil then
+				-- Write the existing session
+				local baseUrl = self.serveSession.__apiContext.__baseUrl
+				self:setRunningConnectionInfo(baseUrl)
+			end
+		else
+			self:clearRunningConnectionInfo()
+		end
+	end)
 end
 
 function App:willUnmount()
 	self.waypointConnection:Disconnect()
 	self.confirmationBindable:Destroy()
+	self.autoConnectPlaytestServerListener()
+	self:clearRunningConnectionInfo()
 end
 
 function App:addNotification(
@@ -278,10 +296,7 @@ function App:getHostAndPort()
 	local host = self.host:getValue()
 	local port = self.port:getValue()
 
-	local host = if #host > 0 then host else Config.defaultHost
-	local port = if #port > 0 then port else Config.defaultPort
-
-	return host, port
+	return if #host > 0 then host else Config.defaultHost, if #port > 0 then port else Config.defaultPort
 end
 
 function App:isSyncLockAvailable()
@@ -349,6 +364,49 @@ function App:releaseSyncLock()
 	Log.trace("Could not relase sync lock because it is owned by {}", lock.Value)
 end
 
+function App:isAutoConnectPlaytestServerAvailable()
+	return RunService:IsRunMode()
+		and RunService:IsServer()
+		and Settings:get("autoConnectPlaytestServer")
+		and workspace:GetAttribute("__Rojo_ConnectionUrl")
+end
+
+function App:isAutoConnectPlaytestServerWriteable()
+	return RunService:IsEdit() and Settings:get("autoConnectPlaytestServer")
+end
+
+function App:setRunningConnectionInfo(baseUrl: string)
+	if not self:isAutoConnectPlaytestServerWriteable() then
+		return
+	end
+
+	Log.trace("Setting connection info for play solo auto-connect")
+	workspace:SetAttribute("__Rojo_ConnectionUrl", baseUrl)
+end
+
+function App:clearRunningConnectionInfo()
+	if not RunService:IsEdit() then
+		-- Only write connection info from edit mode
+		return
+	end
+
+	Log.trace("Clearing connection info for play solo auto-connect")
+	workspace:SetAttribute("__Rojo_ConnectionUrl", nil)
+end
+
+function App:useRunningConnectionInfo()
+	local connectionInfo = workspace:GetAttribute("__Rojo_ConnectionUrl")
+	if not connectionInfo then
+		return
+	end
+
+	Log.trace("Using connection info for play solo auto-connect")
+	local host, port = string.match(connectionInfo, "^(.+):(.-)$")
+
+	self.setHost(host)
+	self.setPort(port)
+end
+
 function App:startSession()
 	local claimedLock, priorOwner = self:claimSyncLock()
 	if not claimedLock then
@@ -441,6 +499,7 @@ function App:startSession()
 			self:addNotification("Connecting to session...")
 		elseif status == ServeSession.Status.Connected then
 			self.knownProjects[details] = true
+			self:setRunningConnectionInfo(baseUrl)
 
 			local address = ("%s:%s"):format(host, port)
 			self:setState({
@@ -453,6 +512,7 @@ function App:startSession()
 		elseif status == ServeSession.Status.Disconnected then
 			self.serveSession = nil
 			self:releaseSyncLock()
+			self:clearRunningConnectionInfo()
 			self:setState({
 				patchData = {
 					patch = PatchSet.newEmpty(),
@@ -488,6 +548,12 @@ function App:startSession()
 			return "Accept"
 		end
 
+		-- Play solo auto-connect does not require confirmation
+		if self:isAutoConnectPlaytestServerAvailable() then
+			Log.trace("Accepting patch without confirmation because play solo auto-connect is enabled")
+			return "Accept"
+		end
+
 		local confirmationBehavior = Settings:get("confirmationBehavior")
 		if confirmationBehavior == "Initial" then
 			-- Only confirm if we haven't synced this project yet this session
@@ -603,7 +669,7 @@ function App:render()
 		value = self.props.plugin,
 	}, {
 		e(Theme.StudioProvider, nil, {
-			e(Tooltip.Provider, nil, {
+			tooltip = e(Tooltip.Provider, nil, {
 				gui = e(StudioPluginGui, {
 					id = pluginName,
 					title = pluginName,