From 4954e47f0e47d0899200124854f0be6b6ab635cc Mon Sep 17 00:00:00 2001
From: overlookmotel <theoverlookmotel@gmail.com>
Date: Sat, 16 May 2020 11:26:26 +0100
Subject: [PATCH] Better enforce symbol naming [fix]

---
 README.md          |  4 ++++
 lib/index.js       | 12 +++++++++---
 test/index.test.js | 18 +++++++++++++-----
 3 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/README.md b/README.md
index 292734e..a22f6aa 100644
--- a/README.md
+++ b/README.md
@@ -44,6 +44,10 @@ symbols.FOO // => Symbol(FOO)
 symbols.BAR // => Symbol(BAR)
 ```
 
+### Naming
+
+Names must only contain upper case letters (`A-Z`), digits (`0-9`), `_` or `$`. They must be valid JS identifiers (i.e. not start with a digit).
+
 ### Symbol store
 
 You can cache all Symbols by passing a `store` option. `store` should be a plain object.
diff --git a/lib/index.js b/lib/index.js
index 1512df7..291996e 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -6,10 +6,12 @@
 'use strict';
 
 // Modules
-const {isObject, isFullString, isArray} = require('is-it-type');
+const {isObject, isString, isFullString, isArray} = require('is-it-type');
 
 // Exports
 
+const NAME_REGEX = /^[A-Z_$][A-Z_$\d]*$/;
+
 module.exports = function makeSymbols(namespace, names, options) {
 	// Conform args
 	if (isArray(namespace)) {
@@ -26,8 +28,12 @@ module.exports = function makeSymbols(namespace, names, options) {
 	// Validate names
 	const namesSet = new Set();
 	for (const name of names) {
-		if (!isFullString(name)) throw new TypeError('names must be an array of strings');
-		if (name.toUpperCase() !== name) throw new Error('symbol names must be all capitalized');
+		if (!isString(name)) throw new TypeError('names must be an array of strings');
+		if (!NAME_REGEX.test(name)) {
+			throw new Error(
+				`'${name}' is not a valid symbol name - must be in SNAKE_CASE and a valid JS identifier`
+			);
+		}
 		if (namesSet.has(name)) {
 			throw new Error(`symbol names must be unique - '${name}' was duplicated`);
 		}
diff --git a/test/index.test.js b/test/index.test.js
index d40ba6b..8c45830 100644
--- a/test/index.test.js
+++ b/test/index.test.js
@@ -95,13 +95,21 @@ describe('throws error if', () => {
 		it('contains empty string', () => {
 			expect(() => {
 				makeSymbols('foo', ['BAR', '']);
-			}).toThrowWithMessage(TypeError, 'names must be an array of strings');
+			}).toThrowWithMessage(Error, "'' is not a valid symbol name - must be in SNAKE_CASE and a valid JS identifier");
 		});
 
-		it('contains a non-capitalized string', () => {
-			expect(() => {
-				makeSymbols('foo', ['BAR', 'Qux']);
-			}).toThrowWithMessage(Error, 'symbol names must be all capitalized');
+		describe('contains invalid string', () => {
+			it.each([
+				'qux',
+				'QUx',
+				'Q.UX',
+				'Q-UX',
+				'1QUX'
+			])('%s', (name) => {
+				expect(() => {
+					makeSymbols('foo', ['BAR', name]);
+				}).toThrowWithMessage(Error, `'${name}' is not a valid symbol name - must be in SNAKE_CASE and a valid JS identifier`);
+			});
 		});
 
 		it('contains duplicates', () => {