fix(debugger): fix an infinite loop issue

src/reactionRunner.js

@@ -5,6 +5,7 @@ import {
 } from './store'
 
 let runningReaction
+let isDebugging = false
 
 export function runAsReaction (reaction, fn, context, args) {
   // do not build reactive relations, if the reaction is unobserved
@@ -30,9 +31,7 @@ export function runAsReaction (reaction, fn, context, args) {
 // register the currently running reaction to be queued again on obj.key mutations
 export function registerRunningReactionForOperation (operation) {
   if (runningReaction) {
-    if (runningReaction.debugger) {
-      runningReaction.debugger(operation)
-    }
+    debugOperation(runningReaction, operation)
     registerReactionForOperation(runningReaction, operation)
   }
 }
@@ -43,9 +42,7 @@ export function queueReactionsForOperation (operation) {
 }
 
 function queueReaction (reaction) {
-  if (reaction.debugger) {
-    reaction.debugger(this)
-  }
+  debugOperation(reaction, this)
   // queue the reaction for later execution or run it immediately
   if (typeof reaction.scheduler === 'function') {
     reaction.scheduler(reaction)
@@ -56,6 +53,17 @@ function queueReaction (reaction) {
   }
 }
 
+function debugOperation (reaction, operation) {
+  if (reaction.debugger && !isDebugging) {
+    try {
+      isDebugging = true
+      reaction.debugger(operation)
+    } finally {
+      isDebugging = false
+    }
+  }
+}
+
 export function hasRunningReaction () {
   return runningReaction !== undefined
 }

tests/debug.test.js

@@ -169,4 +169,17 @@ describe('debugger', () => {
       }
     ])
   })
+
+  it('should not cause infinite loops', () => {
+    let receiverDummy
+    const rawCounter = { num: 0 }
+    const counter = observable(rawCounter)
+    const debugSpy = spy(({ receiver }) => (receiverDummy = receiver.num))
+    observe(() => counter.num, {
+      debugger: debugSpy
+    })
+
+    expect(receiverDummy).to.equal(0)
+    expect(debugSpy.callCount).to.equal(1)
+  })
 })

tests/utils.js

@@ -1,6 +1,6 @@
 export function spy (fn) {
   function spyFn () {
-    fn()
+    fn.apply(this, arguments)
     spyFn.callCount++
     spyFn.lastArgs = Array.from(arguments)
     spyFn.args.push(spyFn.lastArgs)