test(coverage): switch to nyc for coverage from both tests

.gitignore

@@ -12,6 +12,7 @@ lib-cov
 
 # Coverage directory used by tools like istanbul
 coverage
+.nyc_output
 
 # Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
 .grunt

index.js

@@ -205,6 +205,7 @@ function invalidExtras(data, msg) {
 
 function recordName(record) {
   /* eslint no-underscore-dangle: 0 */
+  /* istanbul ignore next */
   return record._name || record.constructor.name || 'Record';
 }
 

package.json

@@ -4,9 +4,11 @@
   "description": "Transit serialisation for Immutable.js",
   "main": "index.js",
   "scripts": {
-    "test": "npm install --no-save immutable@3 && mocha && npm install --no-save immutable@^4.0.0-rc.12 && mocha",
+    "test:3": "npm install --no-save immutable@^3.7.4 && mocha",
+    "test:4": "npm install --no-save immutable@^4.0.0-rc.12 && mocha",
+    "test": "npm run test:3 && npm run test:4",
     "lint": "eslint .",
-    "coverage": "istanbul cover _mocha --"
+    "coverage": "nyc npm test && nyc report --reporter=lcov --reporter=json"
   },
   "repository": {
     "type": "git",
@@ -28,8 +30,8 @@
     "coveralls": "^2.11.2",
     "eslint": "^0.24.1",
     "immutable": ">=3.7.4",
-    "istanbul": "^0.3.14",
     "mocha": "^2.2.5",
+    "nyc": "^14.1.1",
     "transit-js": "^0.8.807"
   }
 }