refactor: improve error traceback

packages/charm/test/effect.test.luau

@@ -408,17 +408,6 @@ test("should run cleanups outside any evaluation context", function()
 	assert(calls == 0, "should not run after b update")
 end)
 
-test.skip("infinite recursion should eventually throw", function()
-	local counter, setCounter = signal(0)
-
-	local success = pcall(function()
-		effect(function()
-			setCounter(counter() + 1)
-		end)
-	end)
-	assert(not success, "should have thrown")
-end)
-
 test("should not retrigger the effect if the cleanup modifies one of the dependencies", function()
 	local a, setA = signal(0)
 	local calls = {}

packages/charm/test/effectScope.test.luau

@@ -92,13 +92,4 @@ test("should dispose inner effects if created in an effect", function()
 	assert(triggers == 2, "ran after dispose")
 end)
 
-test("should disallow yielding", function()
-	local success = pcall(function()
-		effectScope(function()
-			coroutine.yield()
-		end)
-	end)
-	assert(not success, "should error on yield")
-end)
-
 return {}

packages/charm/test/errors.test.luau

@@ -0,0 +1,200 @@
+--!optimize 1
+
+local Charm = require("../src")
+local test = require("../../../tests/test")
+
+test("should disallow yielding", function()
+	local success = pcall(function()
+		Charm.effectScope(function()
+			coroutine.yield()
+		end)
+	end)
+	assert(not success, "should error on yield")
+end)
+
+test.describe("traceback", function()
+	local DEFAULT_ERROR = "Test error"
+
+	local function fail(message: string?)
+		error(message or DEFAULT_ERROR, 0)
+	end
+
+	local function indirectError(message: string?)
+		fail(message)
+	end
+
+	local function assertStackTrace(err: unknown, expectation: string?)
+		expectation = expectation or DEFAULT_ERROR
+		assert(type(err) == "string", "Expected error to be a string")
+		assert(string.find(err, expectation), `Expected error message to be "{expectation}", got: {err}`)
+		assert(string.find(err, "fail"), `Expected stack trace to contain fail, got: {err}`)
+		assert(string.find(err, "indirectError"), `Expected stack trace to contain indirectError, got: {err}`)
+	end
+
+	test("signal update", function()
+		local _, err = pcall(function()
+			local _, setSrc = Charm.signal(0)
+			setSrc(function()
+				indirectError()
+				return 1
+			end)
+		end)
+		assertStackTrace(err)
+	end)
+
+	test("atom update", function()
+		local _, err = pcall(function()
+			local src = Charm.atom(0)
+			src(function()
+				indirectError()
+				return 1
+			end)
+		end)
+		assertStackTrace(err)
+	end)
+
+	test("computed", function()
+		local _, err = pcall(function()
+			local src = Charm.computed(function()
+				indirectError()
+			end)
+			src()
+		end)
+		assertStackTrace(err)
+	end)
+
+	test("effect init", function()
+		local _, err = pcall(function()
+			Charm.effect(function()
+				indirectError()
+			end)
+		end)
+		assertStackTrace(err)
+	end)
+
+	test("effect run", function()
+		local _, err = pcall(function()
+			local src, setSrc = Charm.signal(0)
+			Charm.effect(function()
+				if src() == 1 then
+					indirectError()
+				end
+			end)
+			setSrc(1)
+		end)
+		assertStackTrace(err)
+	end)
+
+	test("effect cleanups", function()
+		local _, err = pcall(function()
+			local dispose = Charm.effect(function()
+				Charm.onCleanup(function()
+					indirectError("onCleanup")
+				end)
+				return function()
+					indirectError("returned cleanup")
+				end
+			end)
+			dispose()
+		end)
+		assertStackTrace(err, "onCleanup")
+		assertStackTrace(err, "returned cleanup")
+	end)
+
+	test("trigger", function()
+		local _, err = pcall(function()
+			Charm.trigger(function()
+				indirectError()
+			end)
+		end)
+		assertStackTrace(err)
+	end)
+
+	test("untracked", function()
+		local _, err = pcall(function()
+			Charm.effectScope(function()
+				Charm.untracked(function()
+					indirectError()
+				end)
+			end)
+		end)
+		assertStackTrace(err)
+	end)
+
+	test("batch", function()
+		local _, err = pcall(function()
+			Charm.batch(function()
+				indirectError()
+			end)
+		end)
+		assertStackTrace(err)
+	end)
+
+	test("subscribe getter", function()
+		local _, err = pcall(function()
+			Charm.subscribe(function()
+				indirectError()
+			end, function() end)
+		end)
+		assertStackTrace(err)
+	end)
+
+	test("subscribe callback", function()
+		local _, err = pcall(function()
+			local src, setSrc = Charm.signal(0)
+			Charm.subscribe(src, function()
+				indirectError()
+			end)
+			setSrc(1)
+		end)
+		assertStackTrace(err)
+	end)
+
+	test("listen getter", function()
+		local _, err = pcall(function()
+			Charm.listen(function()
+				indirectError()
+			end, function() end)
+		end)
+		assertStackTrace(err)
+	end)
+
+	test("listen callback", function()
+		local _, err = pcall(function()
+			local src, setSrc = Charm.signal(0)
+			Charm.listen(src, function()
+				indirectError()
+			end)
+			setSrc(1)
+		end)
+		assertStackTrace(err)
+	end)
+
+	test("mapped getter", function()
+		local _, err = pcall(function()
+			local src = Charm.mapped(function()
+				indirectError()
+				return { 1 }
+			end, function()
+				return 1
+			end)
+			src()
+		end)
+		assertStackTrace(err)
+	end)
+
+	test("mapped transform", function()
+		local _, err = pcall(function()
+			local src = Charm.mapped(function()
+				return { 1 }
+			end, function()
+				indirectError()
+				return 1
+			end)
+			src()
+		end)
+		assertStackTrace(err)
+	end)
+end)
+
+return {}

packages/charm/test/init.luau

@@ -12,6 +12,10 @@ test.describe("effectScope", function()
 	require("@self/effectScope.test")
 end)
 
+test.describe("error", function()
+	require("@self/errors.test")
+end)
+
 test.describe("gc", function()
 	require("@self/gc.test")
 end)

packages/charm/test/observe.test.luau

@@ -167,4 +167,32 @@ test("should allow disposal during removal", function()
 	assert(table.concat(edits) == "+1+2+3+4-1-2-3-4", `bad edits: {table.concat(edits)}`)
 end)
 
+test("should not hang on error after recursive update", function()
+	local items, setItems = signal({})
+
+	observe(items, function()
+		setItems({ {} })
+		error("test error")
+	end)
+
+	local success, err = pcall(function()
+		setItems({ {} })
+	end)
+	assert(not success, "should error")
+	assert(string.find(tostring(err), "test error"), `bad error: {err}`)
+end)
+
+test("should not hang on error after recursive init", function()
+	local items, setItems = signal({ {} })
+
+	local success, err = pcall(function()
+		observe(items, function()
+			setItems({ {} })
+			error("test error")
+		end)
+	end)
+	assert(not success, "should error")
+	assert(string.find(tostring(err), "test error"), `bad error: {err}`)
+end)
+
 return {}