Ensure that STATE configuration from static hints are properly configured with multiple levels of class inheritance

packages/metal-state/src/State.js

@@ -280,8 +280,13 @@ class State extends EventEmitter {
 		if (ctor !== State) {
 			let defineContext;
 			if (this.obj_ === this) {
-				defineContext = ctor.hasConfiguredState_ ? false : ctor.prototype;
-				ctor.hasConfiguredState_ = true;
+				const staticKey = State.STATE_STATIC_HINT_CONFIGURED;
+
+				ctor[staticKey] = ctor[staticKey] || {};
+
+				defineContext = ctor[staticKey][ctor.name] ? false :
+					ctor.prototype;
+				ctor[staticKey][ctor.name] = true;
 			}
 			this.configState(State.getStateStatic(ctor), defineContext);
 		}
@@ -676,8 +681,20 @@ class State extends EventEmitter {
 	}
 }
 
+/**
+ * Constant used as key on State instance for storing property definition.
+ * @type {!string}
+ */
 State.STATE_REF_KEY = '__METAL_STATE_REF_KEY__';
 
+/**
+ * Constant used as key on class constructors that extend form State, stores
+ * which constructors have had their static STATE configured so that
+ * configuration of STATE is not repeated.
+ * @type {!string}
+ */
+State.STATE_STATIC_HINT_CONFIGURED = '__METAL_STATE_STATIC_HINT_CONFIGURED__';
+
 /**
  * Constants that represent the states that a state key can be in.
  * @type {!Object}

packages/metal-state/test/State.js

@@ -1041,6 +1041,32 @@ describe('State', function() {
 			assert.strictEqual('foo2', test2.key1);
 			assert.strictEqual('foo1', test1.key1);
 		});
+
+		it('should configure static STATE with multiple levels of class inheritance', function() {
+			var Test = createTestClass();
+			Test.STATE = {
+				key1: {
+				}
+			};
+
+			class Child extends Test {
+			}
+			Child.STATE = {
+				key2: {
+				}
+			};
+
+			var test = new Test({
+				key1: 'foo1'
+			});
+			assert.strictEqual('foo1', test.key1);
+
+			var child = new Child({
+				key2: 'foo2'
+			});
+			assert.strictEqual('foo1', test.key1);
+			assert.strictEqual('foo2', child.key2);
+		});
 	});
 
 	describe('Separate object', function() {