fix(router): prevent stale onmatch rejections from redirecting

api/router.js

@@ -95,7 +95,11 @@ module.exports = function($window, mountRedraw) {
 					else if (payload.onmatch) {
 						p.then(function () {
 							return payload.onmatch(data.params, path, matchedRoute)
-						}).then(update, path === fallbackRoute ? null : reject)
+						}).then(update, path === fallbackRoute ? null : function(e) {
+							// An obsolete resolver must not redirect a newer navigation.
+							if (update === lastUpdate) reject(e)
+							else console.error(e)
+						})
 					}
 					else update(/* "div" */)
 					return

api/tests/test-router-rejection.js

@@ -0,0 +1,139 @@
+"use strict"
+
+var o = require("ospec")
+var browserMock = require("../../test-utils/browserMock")
+var throttleMocker = require("../../test-utils/throttleMock")
+var m = require("../../render/hyperscript")
+var coreRenderer = require("../../render/render")
+var apiMountRedraw = require("../mount-redraw")
+var apiRouter = require("../router")
+
+o.spec("obsolete onmatch rejection", function() {
+	var $window, root, throttle, route, realError, errorSpy
+
+	function deferred() {
+		var resolve, reject
+		var promise = new Promise(function(a, b) { resolve = a; reject = b })
+		return {promise: promise, resolve: resolve, reject: reject}
+	}
+
+	function settle() {
+		return new Promise(function(resolve) { setTimeout(resolve, 20) }).then(function() {
+			throttle.fire()
+		})
+	}
+
+	o.beforeEach(function() {
+		$window = browserMock()
+		root = $window.document.body
+		throttle = throttleMocker()
+		route = apiRouter($window, apiMountRedraw(coreRenderer($window), throttle.schedule, console))
+		realError = console.error
+		errorSpy = console.error = o.spy()
+	})
+
+	o.afterEach(function() {
+		console.error = realError
+	})
+
+	function setup(old, next) {
+		$window.location.href = "#!/old"
+		route(root, "/home", {
+			"/home": {view: function() { return m("p", "home") }},
+			"/old": {onmatch: function() { return old.promise }},
+			"/next": next || {view: function() { return m("p", "next") }},
+		})
+	}
+
+	o("does not replace an already resolved newer route", function() {
+		var old = deferred()
+		var error = new Error("old load failed")
+		setup(old)
+		return settle().then(function() {
+			route.set("/next")
+			return settle()
+		}).then(function() {
+			o(route.get()).equals("/next")
+			old.reject(error)
+			return settle()
+		}).then(function() {
+			o(route.get()).equals("/next")
+			o(root.firstChild.firstChild.nodeValue).equals("next")
+			o($window.location.hash).equals("#!/next")
+			o(errorSpy.callCount).equals(1)
+			o(errorSpy.args[0]).equals(error)
+		})
+	})
+
+	o("does not cancel a pending newer route", function() {
+		var old = deferred()
+		var next = deferred()
+		setup(old, {onmatch: function() { return next.promise }})
+		return settle().then(function() {
+			route.set("/next")
+			return settle()
+		}).then(function() {
+			old.reject(new Error("old load failed"))
+			return settle()
+		}).then(function() {
+			o($window.location.hash).equals("#!/next")
+			next.resolve({view: function() { return m("p", "loaded") }})
+			return settle()
+		}).then(function() {
+			o(route.get()).equals("/next")
+			o(root.firstChild.firstChild.nodeValue).equals("loaded")
+		})
+	})
+
+	o("preserves a route.set before the new resolver runs", function() {
+		var old = deferred()
+		setup(old)
+		return settle().then(function() {
+			route.set("/next")
+			old.reject(new Error("old load failed"))
+			return settle()
+		}).then(function() {
+			o(route.get()).equals("/next")
+			o($window.location.hash).equals("#!/next")
+		})
+	})
+
+	o("does not cancel a newer navigation to the same path", function() {
+		var old = deferred()
+		var next = deferred()
+		var calls = 0
+		$window.location.href = "#!/old"
+		route(root, "/home", {
+			"/home": {view: function() { return m("p", "home") }},
+			"/old": {onmatch: function() { return ++calls === 1 ? old.promise : next.promise }},
+		})
+		return settle().then(function() {
+			route.set("/old")
+			return settle()
+		}).then(function() {
+			o(calls).equals(2)
+			old.reject(new Error("first load failed"))
+			return settle()
+		}).then(function() {
+			next.resolve({view: function() { return m("p", "reloaded") }})
+			return settle()
+		}).then(function() {
+			o(route.get()).equals("/old")
+			o(root.firstChild.firstChild.nodeValue).equals("reloaded")
+			o($window.location.hash).equals("#!/old")
+		})
+	})
+
+	o("still redirects a current rejected resolver to the fallback", function() {
+		var old = deferred()
+		setup(old)
+		return settle().then(function() {
+			old.reject(new Error("current load failed"))
+			return settle()
+		}).then(function() {
+			o(route.get()).equals("/home")
+			o(root.firstChild.firstChild.nodeValue).equals("home")
+			o(errorSpy.callCount).equals(1)
+		})
+	})
+})