Create git repository with initial commit (#1288)

* Create git repo with initial commit

* Fixe commit message

* Added the git repo to the docs

* Bail if we are in a mercurial repository

* Removed Chore from commit mesage

* Create repo after installing react and react-dom

* Removed docs

* Commit changes when ejecting

* Update after review

* git add -A instead of git add . after code review

packages/react-scripts/scripts/init.js

@@ -17,10 +17,49 @@ process.on('unhandledRejection', err => {
 const fs = require('fs-extra');
 const path = require('path');
 const chalk = require('chalk');
+const execSync = require('child_process').execSync;
 const spawn = require('react-dev-utils/crossSpawn');
 const { defaultBrowsers } = require('react-dev-utils/browsersHelper');
 const os = require('os');
 
+function insideGitRepository() {
+  try {
+    execSync('git rev-parse --is-inside-work-tree', { stdio: 'ignore' });
+    return true;
+  } catch (e) {
+    return false;
+  }
+}
+
+function insideMercurialRepository() {
+  try {
+    execSync('hg --cwd . root', { stdio: 'ignore' });
+    return true;
+  } catch (e) {
+    return false;
+  }
+}
+
+function gitInit() {
+  try {
+    execSync('git --version', { stdio: 'ignore' });
+
+    if (insideGitRepository() || insideMercurialRepository()) {
+      return false;
+    }
+
+    execSync('git init', { stdio: 'ignore' });
+    execSync('git add -A', { stdio: 'ignore' });
+    execSync('git commit -m "Initial commit from Create React App"', {
+      stdio: 'ignore',
+    });
+
+    return true;
+  } catch (e) {
+    return false;
+  }
+}
+
 module.exports = function(
   appPath,
   appName,
@@ -134,6 +173,10 @@ module.exports = function(
     }
   }
 
+  if (gitInit()) {
+    console.log('Initialized git repository');
+  }
+
   // Display the most elegant way to cd.
   // This needs to handle an undefined originalDirectory for
   // backward compatibility with old global-cli's.