feat: add state sync

src/__tests__/sync/server.spec.luau

@@ -0,0 +1,40 @@
+local atom = require(script.Parent.Parent.Parent.atom)
+local sync = require(script.Parent.Parent.Parent.sync)
+
+return function()
+	local target: Player = {} :: any
+
+	it("sends state to new players", function()
+		local a = atom(1)
+		local server = sync.server({ atoms = { a = a }, interval = -1 })
+		local player: Player, payload: sync.SyncPayload
+
+		server:onSync(function(...)
+			player, payload = ...
+		end)
+
+		server:hydrate(target)
+
+		expect(player).to.equal(target)
+		expect(payload.type).to.equal("set")
+		expect(payload.data.a).to.equal(1)
+	end)
+
+	it("sends state patches", function()
+		local a = atom({ b = 1, c = 2 })
+		local server = sync.server({ atoms = { a = a }, interval = -1 })
+		local player: Player, payload: sync.SyncPayload
+
+		server:onSync(function(...)
+			player, payload = ...
+		end)
+
+		a({ b = 1, c = 5 })
+		server:flush(target)
+
+		expect(player).to.equal(target)
+		expect(payload.type).to.equal("patch")
+		expect(payload.data.a.b).to.never.be.ok()
+		expect(payload.data.a.c).to.equal(5)
+	end)
+end