Test userland assert and Node.js core assert

.travis.yml

@@ -2,10 +2,16 @@ language: node_js
 matrix:
   include:
   - node_js: 'stable'
+    env: TASK=test
   - node_js: 'node'
-    env: VERSION=v12.0.0-rc.1
+    env: TASK=test VERSION=v12.0.0-rc.1
     before_install: NVM_NODEJS_ORG_MIRROR=https://nodejs.org/download/rc nvm install $VERSION
-script: npm test
+  - node_js: 'stable'
+    env: TASK=test-native
+  - node_js: 'node'
+    env: TASK=test-native VERSION=v12.0.0-rc.1
+    before_install: NVM_NODEJS_ORG_MIRROR=https://nodejs.org/download/rc nvm install $VERSION
+script: npm run $TASK
 notifications:
   email:
     on_success: never

package.json

@@ -7,14 +7,17 @@
   "homepage": "https://github.com/browserify/commonjs-assert",
   "repository": "browserify/commonjs-assert",
   "scripts": {
-    "test": "node test.js"
+    "test": "node test.js",
+    "test-native": "cross-env TEST_NATIVE=true npm test"
   },
   "keywords": [
     "assert",
     "browser"
   ],
   "devDependencies": {
+    "cross-env": "^5.2.0",
     "glob": "^7.1.3",
+    "proxyquire": "^2.1.0",
     "tape": "^4.10.1"
   }
 }

test.js

@@ -1,13 +1,16 @@
 const test = require('tape');
 const glob = require('glob');
 const path = require('path');
+const proxyquire = require('proxyquire');
+
+const assert = require(process.env.TEST_NATIVE === 'true' ? 'assert' : '.');
 
 const testPaths = glob.sync('test/**/test-assert*.js');
 
 testPaths.forEach(testPath => {
   test(testPath, t => {
     t.doesNotThrow(() => {
-      require(path.resolve(__dirname, testPath));
+      proxyquire(path.resolve(__dirname, testPath), {assert});
     });
     t.end();
   });