Remove extra synchronization in Promise.all

lib/init.lua

@@ -205,15 +205,9 @@ function Promise.all(promises)
 		-- Keep a count of resolved promises because just checking the resolved
 		-- values length wouldn't account for promises that resolve with nil.
 		local resolvedCount = 0
-		local rejected = false
 
 		-- Called when a single value is resolved and resolves if all are done.
 		local function resolveOne(i, ...)
-			if rejected then
-				-- Bail out if this promise has already been rejected.
-				return
-			end
-
 			resolvedValues[i] = ...
 			resolvedCount = resolvedCount + 1
 
@@ -230,9 +224,7 @@ function Promise.all(promises)
 					resolveOne(i, ...)
 				end,
 				function(...)
-					if not rejected then
-						reject(...)
-					end
+					reject(...)
 				end
 			)
 		end

lib/init.spec.lua

@@ -388,5 +388,36 @@ return function()
 			expect(first).to.equal("baz")
 			expect(second).to.equal("qux")
 		end)
+
+		it("should only reject once", function()
+			local rejectA
+			local rejectB
+
+			local a = Promise.new(function(_, reject)
+				rejectA = reject
+			end)
+
+			local b = Promise.new(function(_, reject)
+				rejectB = reject
+			end)
+
+			local combinedPromise = Promise.all({a, b})
+
+			expect(combinedPromise:getStatus()).to.equal(Promise.Status.Started)
+
+			rejectA("foo", "bar")
+
+			expect(combinedPromise:getStatus()).to.equal(Promise.Status.Rejected)
+
+			rejectB("baz", "qux")
+
+			local resultLength, result = pack(combinedPromise:_unwrap())
+			local success, first, second = unpack(result, 1, resultLength)
+
+			expect(resultLength).to.equal(3)
+			expect(success).to.equal(false)
+			expect(first).to.equal("foo")
+			expect(second).to.equal("bar")
+		end)
 	end)
 end