test(core): add tests for CSS ident tokens

package.json

@@ -7,6 +7,7 @@
   "scripts": {
     "dev": "npm run dev -w @penpot-export/cli",
     "build": "npm run build -w @penpot-export/core -w @penpot-export/cli",
+    "test": "npm run test --workspaces --if-present",
     "demo": "npm run generate-css -w demo"
   }
 }

packages/core/package.json

@@ -9,6 +9,8 @@
   ],
   "scripts": {
     "build": "tsc",
+    "pretest": "npm run build",
+    "test": "node --test",
     "format": "prettier -w ."
   },
   "dependencies": {

packages/core/src/lib/css/helpers.test.ts

@@ -0,0 +1,47 @@
+import assert from 'node:assert'
+import { describe, it } from 'node:test'
+
+import { textToCssIdentToken } from './helpers'
+
+describe('CSS helpers', () => {
+  describe('Transforming text to CSS ident tokens', () => {
+    describe('when input text includes ASCII printable characters', () => {
+      it('escapes all ASCII printable characters except ident code points (-, 0-9, A-Z, _, a-z)', () => {
+        const allAsciiPrintableCharacters =
+          '!"#$%&' +
+          "'" +
+          '()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[' +
+          '\\' +
+          ']^_`abcdefghijklmnopqrtuvwxyz{|}~'
+
+        const expect =
+          '\\!\\"\\#\\$\\%\\&' +
+          "\\'" +
+          '\\(\\)\\*\\+\\,-\\.\\/0123456789\\:\\;\\<\\=\\>\\?\\@ABCDEFGHIJKLMNOPQRSTUVWXYZ\\[' +
+          '\\\\' +
+          '\\]\\^_\\`abcdefghijklmnopqrtuvwxyz\\{\\|\\}\\~'
+
+        assert.ok(/^[\x20-\x7E]*$/.test(allAsciiPrintableCharacters))
+        assert.equal(textToCssIdentToken(allAsciiPrintableCharacters), expect)
+      })
+    })
+
+    describe('when input text does NOT start with a ident-start code point', () => {
+      it('escapes starting number', () => {
+        const expect = '\\0123456789'
+
+        assert.equal(textToCssIdentToken('0123456789'), expect)
+      })
+    })
+
+    describe('when input text starts with a hyphen', () => {
+      describe('when the following character is NOT an ident-start code point', () => {
+        it('escapes first number following a hyphen', () => {
+          const expect = '-\\0123456789'
+
+          assert.equal(textToCssIdentToken('-0123456789'), expect)
+        })
+      })
+    })
+  })
+})

packages/core/src/lib/css/helpers.ts

@@ -23,7 +23,7 @@ function escapeCssCharacter(char: string) {
  * letter:                  An uppercase letter or a lowercase letter.
  * non-ASCII code point:    A code point with a value equal to or greater than U+0080 <control>.
  */
-function textToCssIdentToken(str: string) {
+export function textToCssIdentToken(str: string) {
   const normalizedString = str.trim().replace(/\s/g, '_')
 
   const escapedString = normalizedString