feat(directive injector): DiCircularDependencyError -> _CircularDependencyError

And make _CircularDependencyError extends CircularDependencyError
so that catching CircularDependencyError catches any circular dep
error

Author: vicb

lib/core_dom/directive_injector.dart

@@ -26,14 +26,14 @@ final SOURCE_LIGHT_DOM_KEY = new Key(SourceLightDom);
 final TEMPLATE_LOADER_KEY = new Key(TemplateLoader);
 final SHADOW_ROOT_KEY = new Key(ShadowRoot);
 
-final int NO_CONSTRUCTION = 0;
+const int NO_CONSTRUCTION = 0;
 
 // Maximum parent directive injectors that would be traversed.
-final int MAX_TREE_DEPTH = 1 << 30;
+const int MAX_TREE_DEPTH = 1 << 30;
 
 // Maximum number of concurrent constructions a directive injector would
 // support before throwing an error.
-final int MAX_CONSTRUCTION_DEPTH = 50;
+const int MAX_CONSTRUCTION_DEPTH = 50;
 
 const int VISIBILITY_LOCAL                    = -1;
 const int VISIBILITY_DIRECT_CHILD             = -2;
@@ -114,7 +114,7 @@ class DirectiveInjector implements DirectiveBinder {
       , COMPONENT_DIRECTIVE_INJECTOR_KEY
       , KEEP_ME_LAST
       ];
-  
+
   final DirectiveInjector _parent;
   final Injector _appInjector;
   final Node _node;
@@ -323,8 +323,8 @@ class DirectiveInjector implements DirectiveBinder {
 
   dynamic _new(Key k, List<Key> paramKeys, Function fn) {
     if (_constructionDepth > MAX_CONSTRUCTION_DEPTH) {
-      _constructionDepth = NO_CONSTRUCTION;
-      throw new DiCircularDependencyError(key);
+      _constructionDepth = 0;
+      throw new _CircularDependencyError(k);
     }
     bool isFirstConstruction = (_constructionDepth++ == NO_CONSTRUCTION);
     var oldTag = _TAG_GET.makeCurrent();
@@ -433,7 +433,7 @@ class TemplateDirectiveInjector extends DirectiveInjector {
     if (_destLightDom != null) _destLightDom.addViewPort(viewPort);
     return viewPort;
   }
-  
+
 }
 
 class ComponentDirectiveInjector extends DirectiveInjector {
@@ -478,8 +478,8 @@ class ComponentDirectiveInjector extends DirectiveInjector {
 
 // For efficiency we run through the maximum resolving depth and unwind
 // instead of setting 'resolving' key per type.
-class DiCircularDependencyError extends ResolvingError {
-  DiCircularDependencyError(key) : super(key);
+class _CircularDependencyError extends CircularDependencyError {
+  _CircularDependencyError(key) : super(key);
 
   // strips the cyclical part of the chain.
   List<Key> get stripCycle {
@@ -494,6 +494,12 @@ class DiCircularDependencyError extends ResolvingError {
     return rkeys;
   }
 
-  String get resolveChain => stripCycle.join(' -> ');
-  String toString() => "circular dependency (${resolveChain})";
+  String get resolveChain {
+    StringBuffer buffer = new StringBuffer()
+        ..write("(resolving ")
+        ..write(stripCycle.join(' -> '))
+        ..write(")");
+    return buffer.toString();
+  }
+
 }

test/core_dom/directive_injector_spec.dart

@@ -113,8 +113,10 @@ void main() {
           addDirective(_TypeC0);
           addDirective(_TypeC1, Visibility.CHILDREN);
           addDirective(_TypeC2, Visibility.CHILDREN);
-          expect(() => injector.get(_TypeC0)).toThrow(
-              'circular dependency (_TypeC0 -> _TypeC1 -> _TypeC2 -> _TypeC1)');
+          expect(() => injector.get(_TypeC0)).toThrowWith(
+              where: (e) => e is CircularDependencyError,
+              message: 'Cannot resolve a circular dependency! '
+                       '(resolving _TypeC0 -> _TypeC1 -> _TypeC2 -> _TypeC1)');
         });
 
         it('should throw circular dependency error accross injectors', () {
@@ -124,8 +126,10 @@ void main() {
           addDirective(_TypeC0, Visibility.LOCAL, childInjector);
           addDirective(_TypeC1, Visibility.CHILDREN);
           addDirective(_TypeC2, Visibility.CHILDREN);
-          expect(() => childInjector.get(_TypeC0)).toThrow(
-              'circular dependency (_TypeC0 -> _TypeC1 -> _TypeC2 -> _TypeC1)');
+          expect(() => childInjector.get(_TypeC0)).toThrowWith(
+              where: (e) => e is CircularDependencyError,
+              message: 'Cannot resolve a circular dependency! '
+                       '(resolving _TypeC0 -> _TypeC1 -> _TypeC2 -> _TypeC1)');
         });
       });