feat(since): defined a script to run tests on only packages that have changed since HEAD

in order to optimize the verification done with the local git hook

Author: travi

src/lerna-test.js

@@ -23,7 +23,11 @@ suite('lerna scaffolder', () => {
       await scaffold({projectRoot, packageManager}),
       {
         devDependencies: ['lerna'],
-        scripts: {bootstrap: 'lerna bootstrap', 'test:packages': 'lerna run --parallel test'},
+        scripts: {
+          bootstrap: 'lerna bootstrap',
+          'test:packages': 'lerna run --parallel test',
+          'test:packages:since': 'lerna run --parallel test --since HEAD'
+        },
         badges: {
           contribution: {
             lerna: {

src/lerna.js

@@ -8,7 +8,11 @@ export default function ({projectRoot, packageManager}) {
 
   return {
     devDependencies: ['lerna'],
-    scripts: {bootstrap: 'lerna bootstrap', 'test:packages': 'lerna run --parallel test'},
+    scripts: {
+      bootstrap: 'lerna bootstrap',
+      'test:packages': 'lerna run --parallel test',
+      'test:packages:since': 'lerna run --parallel test --since HEAD'
+    },
     badges: {
       contribution: {
         lerna: {

test/integration/features/step_definitions/lerna-steps.js

@@ -9,5 +9,6 @@ Then('lerna will be configured', async function () {
   assert.include(devDependencies, 'lerna');
   assert.equal(scripts.bootstrap, 'lerna bootstrap');
   assert.equal(scripts['test:packages'], 'lerna run --parallel test');
+  assert.equal(scripts['test:packages:since'], 'lerna run --parallel test --since HEAD');
   assert.deepEqual(lernaConfig, {version: 'independent', packages: ['packages/*'], npmClient: this.packageManager});
 });