Fix #31

lib/init.lua

@@ -1221,7 +1221,7 @@ function Promise.prototype:_resolve(...)
 
 	-- We assume that these callbacks will not throw errors.
 	for _, callback in ipairs(self._queuedResolve) do
-		callback(...)
+		coroutine.wrap(callback)(...)
 	end
 
 	self:_finalize()
@@ -1239,7 +1239,7 @@ function Promise.prototype:_reject(...)
 	if not isEmpty(self._queuedReject) then
 		-- We assume that these callbacks will not throw errors.
 		for _, callback in ipairs(self._queuedReject) do
-			callback(...)
+			coroutine.wrap(callback)(...)
 		end
 	else
 		-- At this point, no one was able to observe the error.
@@ -1286,7 +1286,7 @@ function Promise.prototype:_finalize()
 		-- Purposefully not passing values to callbacks here, as it could be the
 		-- resolved values, or rejected errors. If the developer needs the values,
 		-- they should use :andThen or :catch explicitly.
-		callback(self._status)
+		coroutine.wrap(callback)(self._status)
 	end
 
 	-- Clear references to other Promises to allow gc

lib/init.spec.lua

@@ -261,6 +261,30 @@ return function()
 			expect(promise._values[1]).to.equal(5)
 		end)
 
+		it("should run andThens on a new thread", function()
+			local bindable = Instance.new("BindableEvent")
+
+			local resolve
+			local parentPromise = Promise.new(function(_resolve)
+				resolve = _resolve
+			end)
+
+			local deadlockedPromise = parentPromise:andThen(function()
+				bindable.Event:Wait()
+				return 5
+			end)
+
+			local successfulPromise = parentPromise:andThen(function()
+				return "foo"
+			end)
+
+			expect(parentPromise:getStatus()).to.equal(Promise.Status.Started)
+			resolve()
+			expect(successfulPromise:getStatus()).to.equal(Promise.Status.Resolved)
+			expect(successfulPromise._values[1]).to.equal("foo")
+			expect(deadlockedPromise:getStatus()).to.equal(Promise.Status.Started)
+		end)
+
 		it("should chain onto resolved promises", function()
 			local args
 			local argsLength