chore: don't run tests on travis if only docs were changed (#3908)

build/docs-only.js

@@ -0,0 +1,19 @@
+import sh from 'shelljs';
+import path from 'path';
+
+
+export default function(commit, commitRange) {
+  const SINGLE_COMMIT = `git diff-tree --no-commit-id --name-only -r ${commit}`;
+  const COMMIT_RANGE = `git diff --name-only ${commitRange}`;
+
+  let command = SINGLE_COMMIT;
+
+  if (commitRange) {
+    command = COMMIT_RANGE
+  }
+
+  const output = sh.exec(command, {async: false, silent: true}).stdout;
+
+  const files = output.split('\n').filter(Boolean);
+  return files.every((file) => file.startsWith('docs') || path.extname(file) === '.md');
+};

build/grunt.js

@@ -1,6 +1,7 @@
 import {gruntCustomizer, gruntOptionsMaker} from './options-customizer.js';
 import chg from 'chg';
 import npmRun from 'npm-run';
+import isDocsOnly from './docs-only.js';
 
 module.exports = function(grunt) {
   require('time-grunt')(grunt);
@@ -550,13 +551,27 @@ module.exports = function(grunt) {
   grunt.registerTask('default', ['test']);
 
   // The test script includes coveralls only when the TRAVIS env var is set.
-  grunt.registerTask('test', [
-    'build',
-    'shell:noderequire',
-    'shell:browserify',
-    'shell:webpack',
-    'karma:defaults',
-    'test-a11y'].concat(process.env.TRAVIS && 'coveralls').filter(Boolean));
+  grunt.registerTask('test', function() {
+    const tasks = [
+      'build',
+      'shell:noderequire',
+      'shell:browserify',
+      'shell:webpack',
+      'karma:defaults',
+      'test-a11y'
+    ];
+
+    if (process.env.TRAVIS) {
+      if (isDocsOnly(process.env.TRAVIS_COMMIT, process.env.TRAVIS_COMMIT_RANGE)) {
+        grunt.log.write('Not running any tests because only docs were changed');
+        return;
+      }
+
+      tasks.concat(process.env.TRAVIS && 'coveralls').filter(Boolean);
+    }
+
+    grunt.task.run(tasks);
+  });
 
   // Run while developing
   grunt.registerTask('dev', ['connect:dev', 'concurrent:dev']);

package.json

@@ -112,6 +112,7 @@
     "remark-lint": "^5.2.0",
     "remark-toc": "^3.1.0",
     "remark-validate-links": "^5.0.0",
+    "shelljs": "^0.7.5",
     "sinon": "^1.16.1",
     "time-grunt": "^1.1.1",
     "uglify-js": "~2.7.3",