[Tests] improve the travis matrix

Author: ljharb

.travis.yml

@@ -1,4 +1,6 @@
 language: node_js
+os:
+ - linux
 node_js:
   - "12"
   - "10"
@@ -12,3 +14,21 @@ cache:
     - node_modules
 after_success:
   - npm run coveralls
+before_install:
+  - 'case "${TRAVIS_NODE_VERSION}" in 0.*) export NPM_CONFIG_STRICT_SSL=false ;; esac'
+  - 'nvm install-latest-npm'
+install:
+  - 'if [ "${TRAVIS_NODE_VERSION}" = "0.6" ] || [ "${TRAVIS_NODE_VERSION}" = "0.9" ]; then nvm install --latest-npm 0.8 && npm install && nvm use "${TRAVIS_NODE_VERSION}"; else npm install; fi;'
+script:
+  - 'if [ -n "${PRETEST-}" ]; then npm run pretest ; fi'
+  - 'if [ -n "${TEST-}" ]; then npm run tests-only ; fi'
+sudo: false
+env:
+  - TEST=true
+matrix:
+  fast_finish: true
+  include:
+    - node_js: "lts/*"
+      env: PRETEST=true
+  allow_failures:
+    - os: osx

package.json

@@ -10,7 +10,8 @@
     "coveralls": "cat ./reports/lcov.info | coveralls",
     "lint": "eslint .",
     "pretest": "npm run lint",
-    "test": "jest --coverage",
+    "test": "npm run tests-only --",
+    "tests-only": "jest --coverage",
     "test:watch": "npm test -- --watch"
   },
   "devDependencies": {