feat(injector): handle construction errors

- Detect cyclic deps
- Handle initialization errors

modules/di/src/exceptions.js

@@ -50,6 +50,24 @@ export class AsyncBindingError extends ProviderError {
   }
 }
 
+export class CyclicDependencyError extends ProviderError {
+  constructor(key:Key){
+    super(key, function(keys:List) {
+      return `Cannot instantiate cyclic dependency!${constructResolvingPath(keys)}`;
+    });
+  }
+}
+
+export class InstantiationError extends ProviderError {
+  constructor(originalException, key:Key){
+    super(key, function(keys:List) {
+      var first = stringify(ListWrapper.first(keys).token);
+      return `Error during instantiation of ${first}!${constructResolvingPath(keys)}.`+
+        ` ORIGINAL ERROR: ${originalException}`;
+    });
+  }
+}
+
 export class InvalidBindingError extends DIError {
   constructor(binding){
     this.message = `Invalid binding ${binding}`;

modules/di/src/injector.js

@@ -1,10 +1,13 @@
 import {Map, List, MapWrapper, ListWrapper} from 'facade/collection';
 import {Binding, BindingBuilder, bind} from './binding';
-import {ProviderError, NoProviderError, InvalidBindingError, AsyncBindingError} from './exceptions';
+import {ProviderError, NoProviderError, InvalidBindingError,
+  AsyncBindingError, CyclicDependencyError, InstantiationError} from './exceptions';
 import {Type, isPresent, isBlank} from 'facade/lang';
 import {Future, FutureWrapper} from 'facade/async';
 import {Key} from './key';
 
+var _creating = new Object();
+
 export class Injector {
   constructor(bindings:List) {
     var flatten = _flattenBindings(bindings);
@@ -44,6 +47,9 @@ export class Injector {
     if (key.token === Injector) return this._injector(returnFuture);
 
     var instance = this._get(this._instances, keyId);
+    if (instance === _creating) {
+      throw new CyclicDependencyError(key);
+    }
     if (isPresent(instance)) return instance;
 
     var binding = this._get(this._bindings, keyId);
@@ -73,6 +79,8 @@ export class Injector {
   }
 
   _instantiate(key:Key, binding:Binding, returnFuture) {
+    ListWrapper.set(this._instances, key.id, _creating);
+
     if (binding.providedAsFuture && !returnFuture) {
       throw new AsyncBindingError(key);
     }
@@ -85,14 +93,20 @@ export class Injector {
   }
 
   _instantiateSync(key:Key, binding:Binding) {
+    var deps;
+    try {
+      deps = ListWrapper.map(binding.dependencies, d => this._getByKey(d.key, d.asFuture));
+    } catch (e) {
+      if (e instanceof ProviderError) e.addKey(key);
+      throw e;
+    }
+
     try {
-      var deps = ListWrapper.map(binding.dependencies, d => this._getByKey(d.key, d.asFuture));
       var instance = binding.factory(deps);
       ListWrapper.set(this._instances, key.id, instance);
       return instance;
     } catch (e) {
-      if (e instanceof ProviderError) e.addKey(key);
+      throw new InstantiationError(e, key);
-      throw e;
     }
   }
 
@@ -101,11 +115,6 @@ export class Injector {
     var futures = ListWrapper.map(binding.dependencies, d => this._getByKey(d.key, true));
     return FutureWrapper.wait(futures).
       then(binding.factory).
-      catch(function(e) {
-        console.log('sdfsdfsd', e)
-        //e.addKey(key)
-        //return e;
-      }).
       then(function(instance) {
         ListWrapper.set(instances, key.id, instance);
         return instance

modules/di/test/di/injector_spec.js

@@ -2,6 +2,11 @@ import {describe, it, iit, expect, beforeEach} from 'test_lib/test_lib';
 import {Injector, Inject, bind} from 'di/di';
 
 class Engine {}
+class BrokenEngine {
+  constructor() {
+    throw "Broken Engine";
+  }
+}
 class DashboardSoftware {}
 class Dashboard {
   constructor(software: DashboardSoftware){}
@@ -33,6 +38,10 @@ class CarWithInject {
   }
 }
 
+class CyclicEngine {
+  constructor(car:Car){}
+}
+
 class NoAnnotations {
   constructor(secretDependency){}
 }
@@ -151,5 +160,29 @@ export function main() {
       expect(() => injector.get(CarWithDashboard)).
         toThrowError('No provider for DashboardSoftware! (CarWithDashboard -> Dashboard -> DashboardSoftware)');
     });
+
+    it('should throw when trying to instantiate a cyclic dependency', function() {
+      var injector = new Injector([
+        Car,
+        bind(Engine).toClass(CyclicEngine)
+      ]);
+
+      expect(() => injector.get(Car))
+        .toThrowError('Cannot instantiate cyclic dependency! (Car -> Engine -> Car)');
+    });
+
+    it('should show the full path when error happens in a constructor', function() {
+      var injector = new Injector([
+        Car,
+        bind(Engine).toClass(BrokenEngine)
+      ]);
+
+      try {
+        injector.get(Car);
+        throw "Must throw";
+      } catch (e) {
+        expect(e.message).toContain("Error during instantiation of Engine! (Car -> Engine)");
+      }
+    });
   });
 }