feat: finite/ensure

README.md

@@ -115,6 +115,18 @@ coerceToFinite(Infinity); // null
 coerceToFinite(null); // null
 ```
 
+##### `finite/ensure`
+
+If given argument is a finite number coercible value (via [`finite/coerce`](#finitecoerce)) returns result number.
+Otherwise `TypeError` is thrown.
+
+```javascript
+const ensureFinite = require("type/finite/ensure");
+
+ensureFinite(12); // "12"
+ensureFinite(null); // Thrown TypeError: null is not a number
+```
+
 #### Object
 
 _Object_ is assumed to be any non-primitive JavaScript value

finite/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 finite number", arguments[1]);
+};

test/finite/ensure.js

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