Added some basic tests

package.json

@@ -50,24 +50,28 @@
   },
   "homepage": "https://github.com/webextensions/copy-files-from-to#readme",
   "dependencies": {
-    "async": "3.0.1",
-    "chalk": "2.4.2",
-    "cjson": "0.5.0",
-    "cp-file": "7.0.0",
+    "async": "^3.0.1",
+    "chalk": "^2.4.2",
+    "cjson": "^0.5.0",
+    "cp-file": "^7.0.0",
     "fast-glob": "^3.0.1",
     "glob-parent": "^5.0.0",
     "is-glob": "^4.0.1",
     "is-utf8": "^0.2.1",
-    "lodash": "4.17.11",
+    "lodash": "^4.17.11",
     "md5": "^2.2.1",
-    "mkdirp": "0.5.1",
+    "mkdirp": "^0.5.1",
     "note-down": "0.2.2",
-    "request": "2.88.0",
-    "uglify-js": "3.6.0",
-    "yargs": "13.2.4"
+    "request": "^2.88.0",
+    "uglify-js": "^3.6.0",
+    "yargs": "^13.2.4"
   },
   "devDependencies": {
-    "eslint": "5.16.0",
-    "mocha": "6.1.4"
+    "chai": "^4.2.0",
+    "chai-files": "^1.4.0",
+    "eslint": "^5.16.0",
+    "mocha": "^6.1.4",
+    "rimraf": "^2.6.3",
+    "shelljs": "^0.8.3"
   }
 }

test/basic-usage/.gitignore

@@ -1,2 +1,2 @@
-node_modules/
-scripts/
+/node_modules/
+/scripts/