From a6221cc29a229990b32ad862b502b273375b10a4 Mon Sep 17 00:00:00 2001
From: Andrey Kogut <andrey.kogut@uvoteam.com>
Date: Fri, 31 Mar 2017 03:24:53 +0300
Subject: [PATCH] Fix #916: new observed derivations bocomes stale

---
 src/core/derivation.ts | 11 +++++++++++
 test/autorun.js        | 19 ++++++++++++++++++-
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/core/derivation.ts b/src/core/derivation.ts
index 8ea56c692..b0830e9b3 100644
--- a/src/core/derivation.ts
+++ b/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 +163,9 @@ function bindDependencies(derivation: IDerivation) {
 			if (i0 !== i) observing[i0] = dep;
 			i0++;
 		}
+		if (dep['dependenciesState'] > lowestNewObservingDerivationState) {
+			lowestNewObservingDerivationState = dep['dependenciesState'];
+		}
 	}
 	observing.length = i0;
 
@@ -187,6 +191,13 @@ 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) {
diff --git a/test/autorun.js b/test/autorun.js
index cd137d9da..bd4636698 100644
--- a/test/autorun.js
+++ b/test/autorun.js
@@ -84,4 +84,21 @@ test('autorun batches automatically', function(t) {
 	d1()
 	d2()
 	t.end();
-})
\ No newline at end of file
+})
+
+
+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();
+})