Merge branch 'andykog-fix-916', fixes #916

CHANGELOG.md

@@ -1,3 +1,7 @@
+# 3.1.8
+
+* Fixed edge case where `autorun` was not triggered again if a computed value was invalidated by the reaction itself, see [#916](https://github.com/mobxjs/mobx/issues/916)
+
 # 3.1.7
 
 * Reverted ES2015 module changes, as they broke with webpack 2 (will be re-released later)

src/core/derivation.ts

@@ -148,6 +148,7 @@ function bindDependencies(derivation: IDerivation) {
 
 	const prevObserving = derivation.observing;
 	const observing = derivation.observing = derivation.newObserving!;
+	let lowestNewObservingDerivationState = IDerivationState.UP_TO_DATE;
 
 	derivation.newObserving = null; // newObserving shouldn't be needed outside tracking
 
@@ -162,6 +163,12 @@ function bindDependencies(derivation: IDerivation) {
 			if (i0 !== i) observing[i0] = dep;
 			i0++;
 		}
+
+		// Upcast is 'safe' here, because if dep is IObservable, `dependenciesState` will be undefined,
+		// not hitting the condition
+		if ((dep as any as IDerivation).dependenciesState > lowestNewObservingDerivationState) {
+			lowestNewObservingDerivationState = (dep as any as IDerivation).dependenciesState;
+		}
 	}
 	observing.length = i0;
 
@@ -187,6 +194,13 @@ function bindDependencies(derivation: IDerivation) {
 			addObserver(dep, derivation);
 		}
 	}
+
+	// Some new observed derivations might become stale during this derivation computation
+	// so say had no chance to propagate staleness (#916)
+	if (lowestNewObservingDerivationState !== IDerivationState.UP_TO_DATE) {
+		derivation.dependenciesState = lowestNewObservingDerivationState;
+		derivation.onBecomeStale();
+	}
 }
 
 export function clearObserving(derivation: IDerivation) {

test/autorun.js

@@ -84,4 +84,21 @@ test('autorun batches automatically', function(t) {
 	d1()
 	d2()
 	t.end();
-})
+})
+
+
+test('autorun tracks invalidation of unbound dependencies', function(t) {
+	var a = m.observable(0);
+	var b = m.observable(0);
+	var c = m.computed(() => a.get() + b.get());
+	var values = [];
+
+	m.autorun(() => {
+		values.push(c.get());
+		b.set(100);
+	});
+
+	a.set(1);
+	t.deepEqual(values, [0, 100, 101]);
+	t.end();
+})