Adds a range validator

packages/metal-state/src/Config.js

@@ -62,6 +62,16 @@ const Config = {
 	 */
 	func: setPrimitiveValidators('func'),
 
+	/**
+	 * Creates `State` configuration object with a `rangeOf` validator.
+	 * @param {!Number} min The minimum value allowed.
+	 * @param {!Number} max The maximum value allowed.
+	 * @return {ConfigWithValidator} `State` configuration object.
+	 */
+	inRange(min, max) {
+		return this.validator(validators.inRange(min, max));
+	},
+
 	/**
 	 * Function that creates `State` object with an `instanceOf` validator.
 	 * @return {ConfigWithValidator} `State` configuration object.

packages/metal-state/src/validators.js

@@ -40,6 +40,30 @@ const validators = {
 		});
 	},
 
+	/**
+	 * Creates a validator that checks for a value within a range.
+	 * @param {!Number} min The minimum value allowed.
+	 * @param {!Number} max The maximum value allowed.
+	 * @return {!function()}
+	 */
+	inRange: function(min, max) {
+		const minResult = validators.number(min);
+		const maxResult = validators.number(max);
+		if (isInvalid(minResult)) {
+			return minResult;
+		}
+		if (isInvalid(maxResult)) {
+			return maxResult;
+		}
+		return maybe(value => {
+			const valueResult = validators.number(value);
+			if (isInvalid(valueResult)) {
+				return valueResult;
+			}
+			return value >= min && value <= max;
+		});
+	},
+
 	/**
 	 * Creates a validator that checks if a value is an instance of a given class.
 	 * @param {!function()} expectedClass Class to check value against.

packages/metal-state/test/Config.js

@@ -334,4 +334,12 @@ describe('Config', function() {
 		assert.isUndefined(config.config.required);
 		assert.isUndefined(config2.config.required);
 	});
+
+	it('should validate ranges', function() {
+		const config = Config.inRange(0, 100);
+		assert.ok(core.isObject(config));
+		assert.ok(config.config.validator(10));
+		assert.isFalse(config.config.validator(101));
+		assert.ok(config.config.validator('3') instanceof Error);
+	});
 });

packages/metal-state/test/validators.js

@@ -296,4 +296,22 @@ describe('validators', function() {
 
 		assert.equal(resultError, ERROR_MESSAGE);
 	});
+
+	it('should validate a range', function() {
+		const range1 = validators.inRange(0, 100);
+		assert.isTrue(range1(1));
+		assert.isFalse(range1(-1));
+
+		const range2 = validators.inRange('foo', null);
+		assert.ok(range2 instanceof Error);
+
+		const range3 = validators.inRange(1, 'bar');
+		assert.ok(range3 instanceof Error);
+
+		const range4 = validators.inRange(1, 10);
+		assert.isFalse(range4(-1));
+		assert.isFalse(range4(11));
+		assert.ok(range4('foo') instanceof Error);
+		assert.ok(range4({}) instanceof Error);
+	});
 });