Use lerna run to test only what was changed since master

.travis.yml

@@ -3,3 +3,10 @@ language: node_js
 node_js:
   - "lts/*"
   - "stable"
+cache:
+  yarn: true
+  directories:
+    - "node_modules"
+script:
+  - npm run lint
+  - npm test

package.json

@@ -4,8 +4,10 @@
     "lerna": "3.4.2"
   },
   "scripts": {
-    "lint": "node ./scripts/run-in-packages npm run lint",
-    "test": "node ./scripts/run-in-packages npm run test"
+    "lint": "lerna run lint --since master -- --color",
+    "lint:all": "lerna run lint -- --color",
+    "test": "lerna run test --since master -- --colors",
+    "test:all": "lerna run test -- --colors"
   },
   "workspaces": [
     "packages/*"

scripts/run-in-packages.js

@@ -1,21 +0,0 @@
-const path = require("path");
-const { readdirSync, statSync } = require('fs');
-const { execSync } = require("child_process");
-
-const execArgs = { stdio: "inherit", env: process.env };
-const command = process.argv.slice(2).join(' ');
-
-const getDirectories = srcPath => readdirSync(srcPath)
-  .filter(file => statSync(path.join(srcPath, file)).isDirectory());
-
-if (!command) {
-  console.error('No command specified.')
-} else {
-  const cwd = process.cwd();
-  getDirectories('packages').forEach(packageName => {
-    console.log(packageName, path.resolve(__dirname, "../packages/" + packageName));
-    process.chdir(path.resolve(__dirname, "../packages/" + packageName));
-    execSync(command, execArgs);
-  });
-  process.chdir(cwd);
-}