test: add && backport tests from webpack core (#62)

* fix(package): mv uglify2 to `dependencies` && update `peerDependencies` (#45)

* refactor: apply to `webpack-defaults`

* chore(package): update `webpack-defaults v1.0.1...1.4.0`

* chore: rm `yarn.lock`

* ported uglifyjs unit tests from webpack core repo

.babelrc

@@ -5,7 +5,7 @@
       {
         "useBuiltIns": true,
         "targets": {
-          "node": 4.3
+          "node": "4.3"
         },
         "exclude": [
           "transform-async-to-generator",
@@ -17,13 +17,19 @@
   "plugins": [
     [
       "transform-object-rest-spread",
-      { "useBuiltIns": true }
+      {
+        "useBuiltIns": true
+      }
     ]
   ],
   "env": {
     "test": {
-      "presets": ["env"],
-      "plugins": ["transform-object-rest-spread"]
+      "presets": [
+        "env"
+      ],
+      "plugins": [
+        "transform-object-rest-spread"
+      ]
     }
   }
-}
+}

.eslintignore

@@ -1,3 +1,6 @@
+*.snap
 /node_modules
 /dist
 /examples/build
+/coverage/
+/test/stubs

codecov.yml

@@ -0,0 +1,17 @@
+codecov:
+  branch: master
+coverage:
+  precision: 2
+  round: down
+  range: "70...100"
+  status:
+    project:
+      default:
+        target: auto
+    patch:
+      default:
+        target: auto
+    changes:
+      default:
+        branches: null
+comment: off