locked down the signature of Repo#sync with unit tests and an accurat…

…e representation in the README

README.md

@@ -143,14 +143,14 @@ Commit some changes.
 ### `Repo#checkout(treeish, callback)`
 `git checkout <treeish>`
 
-### `Repo#sync([remote_name, ]branch, callback)`
+### `Repo#sync([[remote, ]branch, ]callback)`
 Sync the current branch with the remote, keeping all local changes intact.
 
 The following steps are carried out: `stash`, `pull`, `push`, `stash pop`. If there were no changes to stash, the last `stash pop` is not executed.
 
-  * `remote_name`  - `String`
-  * `branch`       - `String`
-  * `callback`     - Receives `(err)`.
+  * `remote`   - `String` (defaults to `origin`).
+  * `branch`   - `String` (defaults to `master`).
+  * `callback` - Receives `(err)`.
 
 
 ## Commit

package.json

@@ -25,6 +25,7 @@
 , "devDependencies":
   { "should":        "1.2.x"
   , "mocha":         "1.x.x"
+  , "sinon":         "1.6.x"
   , "coffee-script": "1.6.x"
   }
 

src/repo.coffee

@@ -299,18 +299,26 @@ module.exports = class Repo
 
   # Public: Sync the current branch with the remote.
   #
+  # Arguments: ([[remote_name, ]branch_name, ]callback)
+  #
+  # remote_name - String (optional).
+  # branch_name - String.
   # callback - Receives `(err)`.
   #
-  sync: (remote_name, branch, callback) ->
-    [remote_name, callback, branch] = ['origin', branch, remote_name] if !callback
-    [remote_name, callback, branch] = ['origin', remote_name, []]     if !branch
+  sync: (remote_name, branch_name, callback) ->
+
+    # handle 'curried' arguments
+    [remote, branch] = [remote_name, branch_name]                     if typeof callback    is "function"
+    [remote, branch, callback] = ["origin", remote_name, branch_name] if typeof branch_name is "function"
+    [remote, branch, callback] = ["origin", "master", remote_name]    if typeof remote_name is "function"
+
     @status (err, status) =>
       return callback err if err
       @git "stash", {}, ["save"], (err) =>
         return callback err if err
-        @git "pull", {}, [remote_name, branch], (err) =>
+        @git "pull", {}, [remote, branch], (err) =>
           return callback err if err
-          @git "push", {}, [remote_name, branch], (err) =>
+          @git "push", {}, [remote, branch], (err) =>
             return callback err if err
             if not status?.clean
               @git "stash", {}, ["pop"], (err) =>

test/repo.test.coffee

@@ -1,4 +1,5 @@
 should   = require 'should'
+sinon    = require 'sinon'
 fs       = require 'fs'
 fixtures = require './fixtures'
 git      = require '../src'
@@ -13,6 +14,43 @@ Status   = require '../src/status'
 {exec}      = require 'child_process'
 
 describe "Repo", ->
+  describe "#sync", ->
+    describe "when passed curried arguments", ->
+      repo  = fixtures.branched
+      remote = branch = ""
+
+      before ->
+        sinon.stub repo, "git", (command, opts, args, callback) ->
+          if command is "pull"
+            remote = args[0]
+            branch = args[1]
+          callback? null
+        sinon.stub repo, "status", (callback) ->
+          callback? null, clean: no
+
+      after ->
+        repo.git.restore()
+        repo.status.restore()
+
+      it "passes through the correct parameters when nothing is omitted", (done) ->
+        repo.sync "github", "my-branch", ->
+          remote.should.eql "github"
+          branch.should.eql "my-branch"
+          done()
+
+      it "passes through the correct parameters when remote_name is omitted", (done) ->
+        repo.sync "my-branch", ->
+          remote.should.eql "origin"
+          branch.should.eql "my-branch"
+          done()
+
+      it "passes through the correct parameters when remote_name and branch are omitted", (done) ->
+        repo.sync ->
+          remote.should.eql "origin"
+          branch.should.eql "master"
+          done()
+
+
   describe "#identify", ->
     describe "when asked to set the identity's name and email", ->
       repo  = fixtures.branched