Add onTargetEvent to test debugger stub.

circle.yml

@@ -0,0 +1,20 @@
+dependencies:
+  override:
+    - curl -L https://atom.io/download/deb -o atom-amd64.deb
+    - sudo dpkg --install atom-amd64.deb || true
+    - sudo apt-get update
+    - sudo apt-get -f install
+    - node --version
+    - npm --version
+    - atom --version
+    - npm prune
+    - npm install
+    - apm rebuild
+
+test:
+  override:
+    - apm test
+
+machine:
+  node:
+    version: 6.3.0

spec/debugger-stub.js

@@ -25,6 +25,10 @@ export default class DebbugerStub {
     return this.emitter.on('breakpoint', callback)
   }
 
+  onTargetEvent(callback) {
+    return this.emitter.on('target', callback)
+  }
+
   /* For tests */
   emitSessionEvent(notification) {
     this.emitter.emit('session', notification)