build: use nyc for coverage testing

.eslintignore

@@ -1,2 +1,3 @@
+.nyc_output
 coverage
 node_modules

.gitignore

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

.travis.yml

@@ -56,16 +56,18 @@ before_install:
     # Skip updating shrinkwrap / lock
     npm config set shrinkwrap false
   # Setup Node.js version-specific dependencies
-  - |
-    # Configure istanbul for coverage
-    if node_version_lt '0.10'; then npm_remove_module_re '^istanbul$'
-    fi
   - |
     # Configure mocha for testing
     if   node_version_lt '0.10'; then npm_use_module 'mocha' '2.5.3'
     elif node_version_lt '4.0' ; then npm_use_module 'mocha' '3.5.3'
     elif node_version_lt '6.0' ; then npm_use_module 'mocha' '5.2.0'
     fi
+  - |
+    # Configure nyc for testing
+    if   node_version_lt '0.10'; then npm_remove_module_re '^nyc$'
+    elif 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'
+    fi
   - |
     # Configure supertest for http calls
     if   node_version_lt '0.10'; then npm_use_module 'supertest' '1.1.0'
@@ -100,7 +102,7 @@ script:
 after_script:
   - |
     # Upload coverage to coveralls if exists
-    if [[ -e ./coverage/lcov.info ]]; then
+    if [[ -d .nyc_output ]]; then
       npm install --save-dev coveralls@2
-      coveralls < ./coverage/lcov.info
+      nyc report --reporter=text-lcov | coveralls
     fi

package.json

@@ -26,8 +26,8 @@
     "eslint-plugin-node": "8.0.1",
     "eslint-plugin-promise": "4.1.1",
     "eslint-plugin-standard": "4.0.0",
-    "istanbul": "0.4.5",
     "mocha": "6.1.4",
+    "nyc": "14.0.0",
     "supertest": "4.0.2"
   },
   "engines": {
@@ -36,8 +36,8 @@
   "scripts": {
     "lint": "eslint --plugin markdown --ext js,md .",
     "test": "mocha --check-leaks --reporter spec --bail test/",
-    "test-cov": "istanbul cover node_modules/mocha/bin/_mocha -- --check-leaks --reporter dot test/",
-    "test-travis": "istanbul cover node_modules/mocha/bin/_mocha --report lcovonly -- --check-leaks --reporter spec test/"
+    "test-cov": "nyc --reporter=html --reporter=text npm test",
+    "test-travis": "nyc --reporter=text npm test"
   },
   "files": [
     "HISTORY.md",