build: use nyc for coverage testing

.gitignore

@@ -1,3 +1,4 @@
+.nyc_output/
 node_modules/
 coverage/
 npm-debug.log

.travis.yml

@@ -58,6 +58,12 @@ before_install:
     elif node_version_lt '6.0'; then npm_use_module 'mocha' '5.2.0'
     elif node_version_lt '8.0'; then npm_use_module 'mocha' '6.2.2'
     fi
+  - |
+    # Configure nyc for testing
+    if   node_version_lt '4.0'; then npm_use_module 'nyc' '10.3.2'
+    elif node_version_lt '6.0'; then npm_use_module 'nyc' '11.9.0'
+    elif node_version_lt '8.0'; then npm_use_module 'nyc' '14.1.1'
+    fi
   # Update Node.js modules
   - |
     # Prune & rebuild node_modules
@@ -68,15 +74,13 @@ before_install:
 script:
   - |
     # Run test script
-    npm run-script test-travis
+    npm run-script test-ci
   - |
     # Run linting, depending on eslint install
     if npm_module_installed 'eslint'; then npm run-script lint
     fi
 after_script:
   - |
     # Upload coverage to coveralls
-    if [[ -f ./coverage/lcov.info ]]; then
-      npm install --save-dev coveralls@2.13.3
-      coveralls < ./coverage/lcov.info
-    fi
+    npm install --save-dev coveralls@2
+    nyc report --reporter=text-lcov | coveralls

package.json

@@ -25,9 +25,9 @@
   "devDependencies": {
     "eslint": "6.8.0",
     "eslint-plugin-markdown": "1.0.2",
-    "istanbul": "0.4.5",
     "mkdirp": "0.5.4",
     "mocha": "7.1.1",
+    "nyc": "15.0.1",
     "pend": "1.2.0",
     "require-all": "3.0.0",
     "rimraf": "2.6.3",
@@ -45,7 +45,7 @@
   "scripts": {
     "lint": "eslint --plugin markdown --ext js,md .",
     "test": "mocha --reporter spec --bail --check-leaks test/",
-    "test-cov": "istanbul cover node_modules/mocha/bin/_mocha -- --reporter dot --check-leaks test/",
-    "test-travis": "istanbul cover node_modules/mocha/bin/_mocha --report lcovonly -- --reporter spec --check-leaks test/"
+    "test-ci": "nyc --reporter=text npm test",
+    "test-cov": "nyc --reporter=html --reporter=text npm test"
   }
 }