Adds options to throw error if validator returns an Error instance

packages/metal-state/src/State.js

@@ -55,6 +55,14 @@ class State extends EventEmitter {
 		 */
 		this.scheduledBatchData_ = null;
 
+		/**
+		 * Throws exception when validator returns an `Error` instance.
+		 * @type {boolean}
+		 * @default false
+		 * @protected
+		 */
+		this.throwValidationError_ = false;
+
 		/**
 		 * Object that contains information about all this instance's state keys.
 		 * @type {!Object<string, !Object>}
@@ -96,6 +104,21 @@ class State extends EventEmitter {
 		}
 	}
 
+	/**
+	 * Logs an error if the `validatorReturn` is instance of `Error`.
+	 * @param {*} validatorReturn
+	 * @protected
+	 */
+	assertValidatorReturnInstanceOfError_(validatorReturn) {
+		if (validatorReturn instanceof Error) {
+			if (this.getThrowValidationError()) {
+				throw validatorReturn;
+			} else {
+				console.error(`Warning: ${validatorReturn}`);
+			}
+		}
+	}
+
 	/**
 	 * Checks that the given name is a valid state key name. If it's not, an error
 	 * will be thrown.
@@ -178,10 +201,7 @@ class State extends EventEmitter {
 				config.validator,
 				[value, name, this.context_]
 			);
-
-			if (validatorReturn instanceof Error) {
-				console.error(`Warning: ${validatorReturn}`);
-			}
+			this.assertValidatorReturnInstanceOfError_(validatorReturn);
 			return validatorReturn;
 		}
 		return true;
@@ -368,6 +388,15 @@ class State extends EventEmitter {
 		}
 	}
 
+	/**
+	 * Gets the configuration value for whether or not should throw error when
+	 * vaildator functions returns an `Error` instance.
+	 * @return {boolean}
+	 */
+	getThrowValidationError() {
+		return this.throwValidationError_;
+	}
+
 	/**
 	 * Merges the STATE static variable for the given constructor function.
 	 * @param  {!Function} ctor Constructor function.
@@ -607,6 +636,15 @@ class State extends EventEmitter {
 			(isObject(prevVal) || prevVal !== this.get(name));
 	}
 
+	/**
+	 * Sets the configuration value for whether or not should throw error when
+	 * vaildator functions returns an `Error` instance.
+	 * @param {boolean} throwValidationError
+	 */
+	setThrowValidationError(throwValidationError) {
+		this.throwValidationError_ = throwValidationError;
+	}
+
 	/**
 	 * Validates the initial value for the state property with the given name.
 	 * @param {string} name

packages/metal-state/test/State.js

@@ -390,6 +390,39 @@ describe('State', function() {
 		console.error = originalConsoleFn;
 	});
 
+	it('should throw error if validator returns an Error and throwValidationError is enabled', function() {
+		var state = new State();
+		state.setThrowValidationError(true);
+		state.configState(
+			{
+				key1: {
+					validator: function() {
+						return new Error();
+					}
+				}
+			}
+		);
+
+		assert.throws(() => state.key1 = 1);
+	});
+
+	it('should not throw error if validator returns an Error and throwValidationError is disabled', function() {
+		var state = new State();
+		state.setThrowValidationError(false);
+		state.configState(
+			{
+				key1: {
+					validator: function() {
+						return new Error();
+					}
+				}
+			}
+		);
+
+		assert.doesNotThrow(() => state.key1 = 1);
+		assert.strictEqual(1, state.key1);
+	});
+
 	it('should change state new value through setter', function() {
 		var state = new State();
 		state.configState({