feat: handle creating and using forks (#10)

README.md

@@ -11,6 +11,7 @@ Features
 
 - Retrieves the repository’s default branch unless `base` branch is set
 - Makes multiple file changes using a single commit
+- Creates a fork if the authenticated user does not have write access to the repository
 - See [Todos](#todos) for more cool feature ideas! Pull requests welcome!
 
 ## Usage
@@ -42,8 +43,6 @@ octokit.createPullRequest({
 
 ## Todos
 
-- **Creates a fork if necessary**  
-  If the authenticated user does not have write access to the repository then create a fork first.
 - **Deleting files**  
   The challenge with deleting files is hat the [`base_tree` parameter](https://developer.github.com/v3/git/trees/#create-a-tree) cannot be used, meaning the entire tree has to be retrieved, changed, and sent again.
 - **Editing files** based on current content  

lib/create-pull-request.js

@@ -1,13 +1,37 @@
 module.exports = createPullRequest
 
-async function createPullRequest (octokit, { owner, repo, title, body, base, head, changes }) {
-  let response
+async function createPullRequest(
+  octokit,
+  { owner, repo, title, body, base, head, changes }
+) {
+  let response = await octokit.repos.get({ owner, repo })
 
   if (!base) {
-    response = await octokit.repos.get({ owner, repo })
     base = response.data.default_branch
   }
 
+  let fork = owner
+
+  if (!response.data.permissions.push) {
+    const user = await octokit.users.getAuthenticated()
+    const forks = await octokit.repos.listForks({
+      owner,
+      repo
+    })
+    const hasFork = forks.data.find(
+      fork => fork.owner.login === user.data.login
+    )
+
+    if (!hasFork) {
+      await octokit.repos.createFork({
+        owner,
+        repo
+      })
+    }
+
+    fork = user.data.login
+  }
+
   response = await octokit.repos.listCommits({
     owner,
     repo,
@@ -18,7 +42,7 @@ async function createPullRequest (octokit, { owner, repo, title, body, base, hea
   const treeSha = response.data[0].commit.tree.sha
 
   response = await octokit.git.createTree({
-    owner,
+    owner: fork,
     repo,
     base_tree: treeSha,
     tree: Object.keys(changes.files).map(path => {
@@ -32,7 +56,7 @@ async function createPullRequest (octokit, { owner, repo, title, body, base, hea
   const newTreeSha = response.data.sha
 
   response = await octokit.git.createCommit({
-    owner,
+    owner: fork,
     repo,
     message: changes.commit,
     tree: newTreeSha,
@@ -41,7 +65,7 @@ async function createPullRequest (octokit, { owner, repo, title, body, base, hea
   latestCommitSha = response.data.sha
 
   await octokit.git.createRef({
-    owner,
+    owner: fork,
     repo,
     sha: latestCommitSha,
     ref: `refs/heads/${head}`
@@ -50,7 +74,7 @@ async function createPullRequest (octokit, { owner, repo, title, body, base, hea
   response = await octokit.pulls.create({
     owner,
     repo,
-    head,
+    head: `${fork}:${head}`,
     base,
     title,
     body

test/create-fork-test.js

@@ -0,0 +1,39 @@
+const { test } = require('tap')
+
+const Octokit = require('@octokit/rest')
+  .plugin(require('..'))
+
+test('create fork', async t => {
+  const fixtures = require('./fixtures/create-fork')
+  const octokit = new Octokit()
+
+  octokit.hook.wrap('request', (_, options) => {
+    const currentFixtures = fixtures.shift()
+    const { baseUrl, method, url, request, headers, mediaType, ...params } = options
+
+    t.equal(currentFixtures.request.method, options.method)
+    t.equal(currentFixtures.request.url, options.url)
+
+    Object.keys(params).forEach(paramName => {
+      t.deepEqual(currentFixtures.request[paramName], params[paramName])
+    })
+    return currentFixtures.response
+  })
+
+  await octokit.createPullRequest({
+    owner: 'gr2m',
+    repo: 'pull-request-test',
+    title: 'One comes, one goes',
+    body: 'because',
+    head: 'test-branch-u7es0',
+    changes: {
+      files: {
+        'path/to/file1.txt': 'Content for file1',
+        'path/to/file2.txt': 'Content for file2'
+      },
+      commit: 'why'
+    }
+  })
+
+  t.equal(fixtures.length, 0)
+})