Change writer tests so they only refer to the actually saved properties

.editorconfig

@@ -0,0 +1,14 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+indent_style = space
+indent_size = 3
+trim_trailing_whitespace = true
+
+[*.json]
+indent_size = 2
+
+[*.md]
+trim_trailing_whitespace = false

package.json

@@ -20,6 +20,7 @@
     "mkdirp": "~0.5.1"
   },
   "devDependencies": {
+    "@kwsites/file-exists": "^1.0.0",
     "expect.js": "^0.3.1",
     "mocha": "^6.1.4",
     "rimraf": "^2.6.3",
@@ -41,5 +42,8 @@
   "scripts": {
     "test": "mocha ./test/*.spec.js"
   },
+  "engines": {
+    "node": ">=6"
+  },
   "license": "MIT"
 }