build: mocha@6.0.2

.travis.yml

@@ -38,6 +38,14 @@ before_install:
         fs.writeFileSync("package.json", JSON.stringify(p, null, 2) + "\n");
       ' "$@"
     }
+    function npm_use_module () {
+      node -e '
+        fs = require("fs");
+        p = JSON.parse(fs.readFileSync("package.json", "utf8"));
+        p.devDependencies[process.argv[1]] = process.argv[2];
+        fs.writeFileSync("package.json", JSON.stringify(p, null, 2) + "\n");
+      ' "$@"
+    }
     function v () {
       tr '.' '\n' <<< "${1}" \
         | awk '{ printf "%03d", $0 }' \
@@ -56,6 +64,12 @@ before_install:
     # Configure istanbul for coverage
     if node_version_lt '0.10'; then npm_remove_module_re '^istanbul$'
     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
   # Update Node.js modules
   - |
     # Prune & rebuild node_modules

package.json

@@ -25,7 +25,7 @@
     "eslint-plugin-promise": "4.0.1",
     "eslint-plugin-standard": "4.0.0",
     "istanbul": "0.4.5",
-    "mocha": "2.5.3",
+    "mocha": "6.0.2",
     "readable-stream": "2.3.6",
     "safe-buffer": "5.1.2"
   },