add tests for Zalgo behavior (#27)

#26 (comment)

package.json

@@ -44,6 +44,7 @@
     "npm-run-all": "^1.6.0",
     "object-assign": "^4.1.0",
     "own-enumerable-keys": "^1.0.0",
+    "pull-defer": "^0.2.2",
     "pull-delay": "^1.0.1",
     "sheet-router": "^3.0.1",
     "standard": "^7.0.1",

test/zalgo.js

@@ -0,0 +1,91 @@
+const test = require('tape')
+const defer = require('pull-defer')
+const extend = require('extend')
+const inu = require('../')
+const pull = inu.pull
+
+test('infinite loop if sync dispatch, model always new, and effect needs to run async', function (t) {
+  var i = 0
+  var ended = false
+  const app = {
+    init: function () {
+      return { model: {}, effect: 'INIT' }
+    },
+    update: function (model, action) {
+      switch (action) {
+        case 'TICK':
+          return { model: {}, effect: 'NEXT' }
+        case 'DONE':
+          return { model: false }
+      }
+      return { model: model }
+    },
+    view: function (model, dispatch) {
+      if (ended) return
+      if (i++ > 1000) {
+        ended = true
+        t.ok(true)
+        return t.end()
+      }
+      if (model) return dispatch('TICK')
+      t.ok(false)
+    },
+    run: function (effect) {
+      switch (effect) {
+        case 'NEXT':
+          const deferred = defer.source()
+          process.nextTick(function () {
+            deferred.resolve(pull.values(['DONE']))
+          })
+          return deferred
+      }
+    }
+  }
+  const sources = inu.start(app)
+})
+
+test('no infinite loop if async dispatch, model always new, and effect needs to run async', function (t) {
+  var i = 0
+  var ended = false
+  const app = {
+    init: function () {
+      return { model: {}, effect: 'INIT' }
+    },
+    update: function (model, action) {
+      switch (action) {
+        case 'TICK':
+          return { model: {}, effect: 'NEXT' }
+        case 'DONE':
+          return { model: false }
+      }
+      return { model: model }
+    },
+    view: function (model, dispatch) {
+      if (ended) return
+      if (i++ > 1000) {
+        ended = true
+        t.ok(false)
+        return t.end()
+      }
+      if (model) {
+        process.nextTick(() => {
+          return dispatch('TICK')
+        })
+        return
+      }
+      t.ok(true)
+      t.end()
+    },
+    run: function (effect) {
+      switch (effect) {
+        case 'NEXT':
+          const deferred = defer.source()
+          process.nextTick(function () {
+            deferred.resolve(pull.values(['DONE']))
+          })
+          return deferred
+      }
+    }
+  }
+  const sources = inu.start(app)
+})