feat: ensure/number

README.md

@@ -49,10 +49,10 @@ Restricted string coercion. Returns string presentation for every value that fol
 For all other values `null` is returned
 
 ```javascript
-const stringCoerce = require("type/string/coerce");
+const coerceToString = require("type/string/coerce");
 
-stringCoerce(12); // "12"
-stringCoerce(undefined); // null
+coerceToString(12); // "12"
+coerceToString(undefined); // null
 ```
 
 ##### `string/ensure`
@@ -82,11 +82,23 @@ Restricted number coercion. Returns number presentation for every value that fol
 For all other values `null` is returned
 
 ```javascript
-const numberCoerce = require("type/number/coerce");
+const coerceToNumber = require("type/number/coerce");
 
-numberCoerce("12"); // 12
-numberCoerce({}); // null
-numberCoerce(null); // null
+coerceToNumber("12"); // 12
+coerceToNumber({}); // null
+coerceToNumber(null); // null
+```
+
+##### `number/ensure`
+
+If given argument is a number coercible value (via [`number/coerce`](#numbercoerce)) returns result number.
+Otherwise `TypeError` is thrown.
+
+```javascript
+const ensureNumber = require("type/number/ensure");
+
+ensureNumber(12); // "12"
+ensureNumber(null); // Thrown TypeError: null is not a number
 ```
 
 #### Object

number/ensure.js

@@ -0,0 +1,10 @@
+"use strict";
+
+var resolveException = require("../lib/resolve-exception")
+  , coerce           = require("./coerce");
+
+module.exports = function (value/*, options*/) {
+	var coerced = coerce(value);
+	if (coerced !== null) return coerced;
+	return resolveException(value, "%v is not a number", arguments[1]);
+};

test/number/ensure.js

@@ -0,0 +1,17 @@
+"use strict";
+
+var assert       = require("chai").assert
+  , ensureNumber = require("../../number/ensure");
+
+describe("number/ensure", function () {
+	it("Should return coerced value", function () { assert.equal(ensureNumber("12.23"), 12.23); });
+	it("Should crash on no value", function () {
+		try {
+			ensureNumber(null);
+			throw new Error("Unexpected");
+		} catch (error) {
+			assert.equal(error.name, "TypeError");
+			assert.equal(error.message, "null is not a number");
+		}
+	});
+});