fix test runner

Author: developit

.gitignore

@@ -2,7 +2,7 @@
 /test-reports
 /node_modules
 /npm-debug.log
+package-lock.json
 .DS_Store
 .idea
-.reify-cache
 flow-typed

package.json

@@ -8,7 +8,7 @@
   "umd:main": "dist/mitt.umd.js",
   "scripts": {
     "bump": "standard-version",
-    "testonly": "mocha --require reify/node --require flow-remove-types/register test/**/*.js",
+    "testonly": "mocha --require esm --require flow-remove-types/register test/**/*.js",
     "lint": "eslint src test",
     "test": "flow && npm run lint && npm run testonly",
     "build": "npm-run-all --silent clean -p rollup -p minify:* -s docs size",
@@ -73,13 +73,13 @@
     "chai": "^3.5.0",
     "documentation": "^4.0.0-beta4",
     "eslint": "^3.13.1",
+    "esm": "^3.2.25",
     "flow-bin": "^0.38.0",
     "flow-remove-types": "^1.2.0",
     "gzip-size-cli": "^1.0.0",
     "mocha": "^3.2.0",
     "npm-run-all": "^2.1.1",
     "pretty-bytes-cli": "^2.0.0",
-    "reify": "^0.8.3",
     "rimraf": "^2.5.2",
     "rollup": "^0.41.4",
     "rollup-plugin-buble": "^0.15.0",