Add support for providing a default line-height for each font-size

__tests__/plugins/fontSize.test.js

@@ -0,0 +1,30 @@
+import invokePlugin from '../util/invokePlugin'
+import plugin from '../../src/plugins/fontSize'
+
+test('font-size utilities can include a default line-height', () => {
+  const config = {
+    theme: {
+      fontSize: {
+        sm: '12px',
+        md: ['16px', '24px'],
+        lg: ['20px', '28px'],
+      },
+    },
+    variants: {
+      fontSize: ['responsive'],
+    },
+  }
+
+  const { utilities } = invokePlugin(plugin(), config)
+
+  expect(utilities).toEqual([
+    [
+      {
+        '.text-sm': { 'font-size': '12px' },
+        '.text-md': { 'font-size': '16px', 'line-height': '24px' },
+        '.text-lg': { 'font-size': '20px', 'line-height': '28px' },
+      },
+      ['responsive'],
+    ],
+  ])
+})