Let Promise:expect() throw rejection objects

CHANGELOG.md

@@ -9,6 +9,7 @@
 - Promise.async has been renamed to Promise.defer (Promise.async references same function for compatibility)
 - Improve test coverage for asynchronous and time-driven functions
 - Change Promise.is to be safe when dealing with tables that have an `__index` metamethod that creates an error.
+- Let Promise:expect() throw rejection objects
 
 # 2.5.1
 

lib/init.lua

@@ -932,13 +932,13 @@ end
 --[[
 	Calls awaitStatus internally, returns (isResolved, values...)
 ]]
-function Promise.prototype:await(...)
+function Promise.prototype:await()
-	return awaitHelper(self:awaitStatus(...))
+	return awaitHelper(self:awaitStatus())
 end
 
 local function expectHelper(status, ...)
 	if status ~= Promise.Status.Resolved then
-		error((...) == nil and "" or tostring((...)), 3)
+		error((...) == nil and "Expected Promise rejected with no value." or (...), 3)
 	end
 
 	return ...
@@ -948,8 +948,8 @@ end
 	Calls await and only returns if the Promise resolves.
 	Throws if the Promise rejects or gets cancelled.
 ]]
-function Promise.prototype:expect(...)
+function Promise.prototype:expect()
-	return expectHelper(self:awaitStatus(...))
+	return expectHelper(self:awaitStatus())
 end
 
 -- Backwards compatibility

lib/init.spec.lua

@@ -1161,4 +1161,32 @@ return function()
 			expect(promises[3]:getStatus()).to.equal(Promise.Status.Started)
 		end)
 	end)
+
+	describe("Promise:await", function()
+		it("should return the correct values", function()
+			local promise = Promise.resolve(5, 6, nil, 7)
+
+			local a, b, c, d, e = promise:await()
+
+			expect(a).to.equal(true)
+			expect(b).to.equal(5)
+			expect(c).to.equal(6)
+			expect(d).to.equal(nil)
+			expect(e).to.equal(7)
+		end)
+	end)
+
+	describe("Promise:expect", function()
+		it("should throw the correct values", function()
+			local rejectionValue = {}
+			local promise = Promise.reject(rejectionValue)
+
+			local success, value = pcall(function()
+				promise:expect()
+			end)
+
+			expect(success).to.equal(false)
+			expect(value).to.equal(rejectionValue)
+		end)
+	end)
 end