add integration tests

.travis.yml

@@ -0,0 +1,3 @@
+language: node_js
+node_js:
+  - "lts/*"

README.md

@@ -1,5 +1,7 @@
 # postcss-combine-media-query
 
+[![Build Status](https://travis-ci.com/SassNinja/postcss-combine-media-query.svg?branch=master)](https://travis-ci.com/SassNinja/postcss-combine-media-query)
+
 If you are used to write the media queries of your components within those components (what you should do instead of maintaining a large global media query file) you might end up with CSS that contains the same media query rule multiple times.
 
 ```css

package.json

@@ -5,7 +5,9 @@
   "author": "Kai Falkowski",
   "license": "MIT",
   "main": "index.js",
-  "scripts": {},
+  "scripts": {
+    "test": "jest"
+  },
   "keywords": [
     "postcss",
     "plugin",
@@ -16,10 +18,12 @@
     "combine",
     "optimization"
   ],
-  "peerDependencies": {
+  "dependencies": {
     "postcss": "^7.0.21"
   },
-  "devDependencies": {},
+  "devDependencies": {
+    "jest": "^24.9.0"
+  },
   "repository": {
     "type": "git",
     "url": "https://github.com/SassNinja/postcss-combine-media-query.git"

test/default.data.js

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+
+module.exports = `
+    .foo {
+        color: red;
+    }
+    @media (min-width: 1024px) {
+        .foo {
+            color: green;
+        }
+    }
+    @media (min-width: 1200px) {
+        .foo {
+            color: blue;
+        }
+    }
+    .bar {
+        font-size: 1rem;
+        @supports (display: grid) {
+            display: block;
+        }
+    }
+    @media (min-width: 1024px) {
+        .bar {
+            font-size: 2rem;
+            @supports (display: grid) {
+                display: grid;
+            }
+        }
+    }
+    @media screen and (min-width: 1024px) {
+        .bar {
+            content: 'similar but different query'
+        }
+    }
+`;

test/default.test.js

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+
+const postcss = require('postcss');
+const plugin = require('../index');
+const data = require('./default.data');
+
+let root;
+
+beforeAll(() => {
+    root = postcss([plugin()]).process(data).root;
+});
+
+test('should combine equal media rules', () => {
+    let count = 0;
+
+    root.walkAtRules('media', rule => {
+        count++;
+    });
+    expect(count).toBe(3);
+});
+
+test('should move all media rules to the end', () => {
+    let endsWithMedia = true;
+    let hasMedia = false;
+
+    root.nodes.forEach(node => {
+        if (node.name === 'media') {
+            hasMedia = true;
+        }
+        if (hasMedia && node.name !== 'media') {
+            endsWithMedia = false;
+        }
+        expect(endsWithMedia).toBe(true);
+    });
+});