add test file simple_signal2.test.ts, which shows that my current w…

…ay of traversing in `Context.fireUpdateCycle` and `Context.propagateSignalUpdate` are not ordered topologically.

- expected traversal: A, B, D, G, C, E, H, F, I, J
- actual traversal: A, B, D, G, C, E, H,I, J, F
- reason: F gets skipped in the middle because it is already visited once from either B or D, but its resolution is delayed because of unvisited dependencies C and E. however, when C and E are visited, they propagate forward to H and then I. in I's perspective, F has been resolved, since it has been visited. however, the reality is that while it has been visited, it was awaiting dependency resolution of C and E, and it hasn't been resolved yet. the forward propagation model is indeed problematic. you should either stick backward resolution or forward propagation, but not both at the same time.

test/simple_signal2.test.ts

@@ -0,0 +1,40 @@
+import { DEBUG } from "../src/deps.ts"
+import { Context } from "../src/context.ts"
+import { EffectSignal_Factory, LazySignal_Factory, MemoSignal_Factory, StateSignal_Factory } from "../src/signal.ts"
+
+const
+	ctx = new Context(),
+	createState = ctx.addClass(StateSignal_Factory),
+	createMemo = ctx.addClass(MemoSignal_Factory),
+	createLazy = ctx.addClass(LazySignal_Factory),
+	createEffect = ctx.addClass(EffectSignal_Factory),
+	setFn = ctx.dynamic.setFn
+
+const
+	[, A, setA] = createState(1, { equals: false, name: "A" }),
+	[, B] = createMemo((id) => A(id), { equals: false, name: "B" }),
+	[, C] = createMemo((id) => A(id), { equals: false, name: "C" }),
+	[, D] = createMemo((id) => B(id), { equals: false, name: "D" }),
+	[, E] = createMemo((id) => C(id), { equals: false, name: "E" }),
+	[, F] = createMemo((id) => B(id) + C(id) + D(id) + E(id), { equals: false, name: "F" }),
+	[, G] = createMemo((id) => D(id), { equals: false, name: "G" }),
+	[, H] = createMemo((id) => E(id), { equals: false, name: "H" }),
+	[, I] = createMemo((id) => F(id) + G(id) + H(id), { equals: false, name: "I" }),
+	[, J] = createMemo((id) => I(id), { equals: false, name: "J" })
+
+// @ts-ignore: enums can't be modified, but we want to control our logging here
+// DEBUG.LOG = 1
+// I()
+// J()
+
+Deno.test("test1", () => {
+	// @ts-ignore: enums can't be modified, but we want to control our logging here
+	DEBUG.LOG = 1
+	I()
+	J()
+})
+
+Deno.test("test2", () => {
+	DEBUG.LOG = 1
+	setA(2)
+})