--- /dev/null
+# selector-list-comma-space-before
+
+Require a single space or disallow whitespace before the commas of selector lists.
+
+```css
+ a ,b { color: pink; }
+/** ↑
+ * The space before this comma */
+```
+
+## Options
+
+`string`: `"always"|"never"|"always-single-line"|"never-single-line"`
+
+### `"always"`
+
+There *must always* be a single space before the commas.
+
+The following patterns are considered violations:
+
+```css
+a,b { color: pink; }
+```
+
+```css
+a, b { color: pink; }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a ,b { color: pink; }
+```
+
+```css
+a , b { color: pink; }
+```
+
+### `"never"`
+
+There *must never* be whitespace before the commas.
+
+The following patterns are considered violations:
+
+```css
+a ,b { color: pink; }
+```
+
+```css
+a , b { color: pink; }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a,b { color: pink; }
+```
+
+```css
+a, b { color: pink; }
+```
+
+### `"always-single-line"`
+
+There *must always* be a single space before the commas in single-line selector lists.
+
+The following patterns are considered violations:
+
+```css
+a,b { color: pink; }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a,
+b { color: pink; }
+```
+
+### `"never-single-line"`
+
+There *must never* be a single space before the commas in single-line selector lists.
+
+The following patterns are considered violations:
+
+```css
+a ,b { color: pink; }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a ,
+b { color: pink; }
+```