postcss-css-variables no warnings or messages.

app.css

:root {
	--font-family: 'Wingdings', 'Comic Sans', 'Papyrus', sans-serif;
}

body {
	font-family: var(--font-family);
	color: var(--black);
}

index.js

var postcss = require('postcss');
var readFile = require('fs').readFileSync;

var css = readFile('./app.css');

postcss([require('postcss-css-variables')])
.process(css).
then(function(results) {
	console.log(results.messages);
	console.log(results.warnings());
	console.log(results.css);
});

package.json

{
  "name": "postcss-variables-no-warnigns",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "postcss": "^5.0.15",
    "postcss-css-variables": "^0.5.1"
  }
}