feat: onComplete config option (#4322)

* feat: `onComplete` config option

* tests(e2e): add case for onComplete option

src/core/plugins/on-complete/index.js

@@ -0,0 +1,28 @@
+let engaged = false
+
+export default function() {
+
+  return {
+    statePlugins: {
+      spec: {
+        wrapActions: {
+          updateSpec: (ori) => (...args) => {
+            engaged = true
+            return ori(...args)
+          },
+          updateJsonSpec: (ori, system) => (...args) => {
+            const cb = system.getConfigs().onComplete
+            if(engaged && typeof cb === "function") {
+              // call `onComplete` on next tick, which allows React to
+              // reconcile the DOM before we notify the user
+              setTimeout(cb, 0)
+              engaged = false
+            }
+
+            return ori(...args)
+          }
+        }
+      }
+    }
+  }
+}

src/core/presets/base.js

@@ -13,6 +13,7 @@ import downloadUrlPlugin from "core/plugins/download-url"
 import configsPlugin from "core/plugins/configs"
 import deepLinkingPlugin from "core/plugins/deep-linking"
 import filter from "core/plugins/filter"
+import onComplete from "core/plugins/on-complete"
 
 import OperationContainer from "core/containers/OperationContainer"
 
@@ -159,6 +160,7 @@ export default function() {
     SplitPaneModePlugin,
     downloadUrlPlugin,
     deepLinkingPlugin,
-    filter
+    filter,
+    onComplete
   ]
 }