config: adds branches to config for tracking branches against remotes, updates clone to track when cloning a branch. Fixes #313

Signed-off-by: Jeremy Chambers <jeremy@thehipbot.com>

4 files changed, 284 insertions, 5 deletions

diff --git a/config/branch.go b/config/branch.go
new file mode 100644
index 0000000..e18073c
--- /dev/null
+++ b/config/branch.go
@@ -0,0 +1,71 @@
+package config
+
+import (
+	"errors"
+
+	"gopkg.in/src-d/go-git.v4/plumbing"
+	format "gopkg.in/src-d/go-git.v4/plumbing/format/config"
+)
+
+var (
+	errBranchEmptyName    = errors.New("branch config: empty name")
+	errBranchInvalidMerge = errors.New("branch config: invalid merge")
+)
+
+// Branch contains information on the
+// local branches and which remote to track
+type Branch struct {
+	// Name of branch
+	Name string
+	// Remote name of remote to track
+	Remote string
+	// Merge is the local refspec for the branch
+	Merge plumbing.ReferenceName
+
+	raw *format.Subsection
+}
+
+// Validate validates fields of branch
+func (b *Branch) Validate() error {
+	if b.Name == "" {
+		return errBranchEmptyName
+	}
+
+	if b.Merge != "" && !b.Merge.IsBranch() {
+		return errBranchInvalidMerge
+	}
+
+	return nil
+}
+
+func (b *Branch) marshal() *format.Subsection {
+	if b.raw == nil {
+		b.raw = &format.Subsection{}
+	}
+
+	b.raw.Name = b.Name
+
+	if b.Remote == "" {
+		b.raw.RemoveOption(remoteSection)
+	} else {
+		b.raw.SetOption(remoteSection, b.Remote)
+	}
+
+	if b.Merge == "" {
+		b.raw.RemoveOption(mergeKey)
+	} else {
+		b.raw.SetOption(mergeKey, string(b.Merge))
+	}
+
+	return b.raw
+}
+
+func (b *Branch) unmarshal(s *format.Subsection) error {
+	b.raw = s
+
+	b.Name = b.raw.Name
+	b.Remote = b.raw.Options.Get(remoteSection)
+	b.Merge = plumbing.ReferenceName(b.raw.Options.Get(mergeKey))
+
+	return b.Validate()
+}
diff --git a/config/branch_test.go b/config/branch_test.go
new file mode 100644
index 0000000..d74122e
--- /dev/null
+++ b/config/branch_test.go
@@ -0,0 +1,76 @@
+package config
+
+import (
+	. "gopkg.in/check.v1"
+	"gopkg.in/src-d/go-git.v4/plumbing"
+)
+
+type BranchSuite struct{}
+
+var _ = Suite(&BranchSuite{})
+
+func (b *BranchSuite) TestValidateName(c *C) {
+	goodBranch := Branch{
+		Name:   "master",
+		Remote: "some_remote",
+		Merge:  "refs/heads/master",
+	}
+	badBranch := Branch{
+		Remote: "some_remote",
+		Merge:  "refs/heads/master",
+	}
+	c.Assert(goodBranch.Validate(), IsNil)
+	c.Assert(badBranch.Validate(), NotNil)
+}
+
+func (b *BranchSuite) TestValidateMerge(c *C) {
+	goodBranch := Branch{
+		Name:   "master",
+		Remote: "some_remote",
+		Merge:  "refs/heads/master",
+	}
+	badBranch := Branch{
+		Name:   "master",
+		Remote: "some_remote",
+		Merge:  "blah",
+	}
+	c.Assert(goodBranch.Validate(), IsNil)
+	c.Assert(badBranch.Validate(), NotNil)
+}
+
+func (b *BranchSuite) TestMarshall(c *C) {
+	expected := []byte(`[core]
+	bare = false
+[branch "branch-tracking-on-clone"]
+	remote = fork
+	merge = refs/heads/branch-tracking-on-clone
+`)
+
+	cfg := NewConfig()
+	cfg.Branches["branch-tracking-on-clone"] = &Branch{
+		Name:   "branch-tracking-on-clone",
+		Remote: "fork",
+		Merge:  plumbing.ReferenceName("refs/heads/branch-tracking-on-clone"),
+	}
+
+	actual, err := cfg.Marshal()
+	c.Assert(err, IsNil)
+	c.Assert(string(actual), Equals, string(expected))
+}
+
+func (b *BranchSuite) TestUnmarshall(c *C) {
+	input := []byte(`[core]
+	bare = false
+[branch "branch-tracking-on-clone"]
+	remote = fork
+	merge = refs/heads/branch-tracking-on-clone
+`)
+
+	cfg := NewConfig()
+	err := cfg.Unmarshal(input)
+	c.Assert(err, IsNil)
+	branch := cfg.Branches["branch-tracking-on-clone"]
+	c.Assert(branch.Name, Equals, "branch-tracking-on-clone")
+	c.Assert(branch.Remote, Equals, "fork")
+	c.Assert(branch.Merge, Equals, plumbing.ReferenceName("refs/heads/branch-tracking-on-clone"))
+}
diff --git a/config/config.go b/config/config.go
index 87a847d..c730015 100644
--- a/config/config.go
+++ b/config/config.go
@@ -25,7 +25,7 @@ type ConfigStorer interface {
 }
 
 var (
-	ErrInvalid               = errors.New("config invalid remote")
+	ErrInvalid               = errors.New("config invalid key in remote or branch")
 	ErrRemoteConfigNotFound  = errors.New("remote config not found")
 	ErrRemoteConfigEmptyURL  = errors.New("remote config: empty URL")
 	ErrRemoteConfigEmptyName = errors.New("remote config: empty name")
@@ -55,7 +55,9 @@ type Config struct {
 	// Submodules list of repository submodules, the key of the map is the name
 	// of the submodule, should equal to Submodule.Name.
 	Submodules map[string]*Submodule
-
+	// Branches list of branches, the key is the branch name and should
+	// equal Branch.Name
+	Branches map[string]*Branch
 	// Raw contains the raw information of a config file. The main goal is
 	// preserve the parsed information from the original format, to avoid
 	// dropping unsupported fields.
@@ -67,6 +69,7 @@ func NewConfig() *Config {
 	config := &Config{
 		Remotes:    make(map[string]*RemoteConfig),
 		Submodules: make(map[string]*Submodule),
+		Branches:   make(map[string]*Branch),
 		Raw:        format.New(),
 	}
 
@@ -87,12 +90,23 @@ func (c *Config) Validate() error {
 		}
 	}
 
+	for name, b := range c.Branches {
+		if b.Name != name {
+			return ErrInvalid
+		}
+
+		if err := b.Validate(); err != nil {
+			return err
+		}
+	}
+
 	return nil
 }
 
 const (
 	remoteSection    = "remote"
 	submoduleSection = "submodule"
+	branchSection    = "branch"
 	coreSection      = "core"
 	packSection      = "pack"
 	fetchKey         = "fetch"
@@ -100,6 +114,7 @@ const (
 	bareKey          = "bare"
 	worktreeKey      = "worktree"
 	windowKey        = "window"
+	mergeKey         = "merge"
 
 	// DefaultPackWindow holds the number of previous objects used to
 	// generate deltas. The value 10 is the same used by git command.
@@ -121,6 +136,11 @@ func (c *Config) Unmarshal(b []byte) error {
 		return err
 	}
 	c.unmarshalSubmodules()
+
+	if err := c.unmarshalBranches(); err != nil {
+		return err
+	}
+
 	return c.unmarshalRemotes()
 }
 
@@ -172,12 +192,27 @@ func (c *Config) unmarshalSubmodules() {
 	}
 }
 
+func (c *Config) unmarshalBranches() error {
+	bs := c.Raw.Section(branchSection)
+	for _, sub := range bs.Subsections {
+		b := &Branch{}
+
+		if err := b.unmarshal(sub); err != nil {
+			return err
+		}
+
+		c.Branches[b.Name] = b
+	}
+	return nil
+}
+
 // Marshal returns Config encoded as a git-config file.
 func (c *Config) Marshal() ([]byte, error) {
 	c.marshalCore()
 	c.marshalPack()
 	c.marshalRemotes()
 	c.marshalSubmodules()
+	c.marshalBranches()
 
 	buf := bytes.NewBuffer(nil)
 	if err := format.NewEncoder(buf).Encode(c.Raw); err != nil {
@@ -245,6 +280,33 @@ func (c *Config) marshalSubmodules() {
 	}
 }
 
+func (c *Config) marshalBranches() {
+	s := c.Raw.Section(branchSection)
+	newSubsections := make(format.Subsections, 0, len(c.Branches))
+	added := make(map[string]bool)
+	for _, subsection := range s.Subsections {
+		if branch, ok := c.Branches[subsection.Name]; ok {
+			newSubsections = append(newSubsections, branch.marshal())
+			added[subsection.Name] = true
+		}
+	}
+
+	branchNames := make([]string, 0, len(c.Branches))
+	for name := range c.Branches {
+		branchNames = append(branchNames, name)
+	}
+
+	sort.Strings(branchNames)
+
+	for _, name := range branchNames {
+		if !added[name] {
+			newSubsections = append(newSubsections, c.Branches[name].marshal())
+		}
+	}
+
+	s.Subsections = newSubsections
+}
+
 // RemoteConfig contains the configuration for a given remote repository.
 type RemoteConfig struct {
 	// Name of the remote
diff --git a/config/config_test.go b/config/config_test.go
index 1f120c0..5cd713e 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -1,6 +1,9 @@
 package config
 
-import . "gopkg.in/check.v1"
+import (
+	. "gopkg.in/check.v1"
+	"gopkg.in/src-d/go-git.v4/plumbing"
+)
 
 type ConfigSuite struct{}
 
@@ -47,7 +50,8 @@ func (s *ConfigSuite) TestUnmarshall(c *C) {
 	c.Assert(cfg.Submodules["qux"].Name, Equals, "qux")
 	c.Assert(cfg.Submodules["qux"].URL, Equals, "https://github.com/foo/qux.git")
 	c.Assert(cfg.Submodules["qux"].Branch, Equals, "bar")
-
+	c.Assert(cfg.Branches["master"].Remote, Equals, "origin")
+	c.Assert(cfg.Branches["master"].Merge, Equals, plumbing.ReferenceName("refs/heads/master"))
 }
 
 func (s *ConfigSuite) TestMarshall(c *C) {
@@ -65,6 +69,9 @@ func (s *ConfigSuite) TestMarshall(c *C) {
 	url = git@github.com:mcuadros/go-git.git
 [submodule "qux"]
 	url = https://github.com/foo/qux.git
+[branch "master"]
+	remote = origin
+	merge = refs/heads/master
 `)
 
 	cfg := NewConfig()
@@ -87,6 +94,12 @@ func (s *ConfigSuite) TestMarshall(c *C) {
 		URL:  "https://github.com/foo/qux.git",
 	}
 
+	cfg.Branches["master"] = &Branch{
+		Name:   "master",
+		Remote: "origin",
+		Merge:  "refs/heads/master",
+	}
+
 	b, err := cfg.Marshal()
 	c.Assert(err, IsNil)
 
@@ -118,6 +131,29 @@ func (s *ConfigSuite) TestUnmarshallMarshall(c *C) {
 	c.Assert(string(output), DeepEquals, string(input))
 }
 
+func (s *ConfigSuite) TestValidateConfig(c *C) {
+	config := &Config{
+		Remotes: map[string]*RemoteConfig{
+			"bar": {
+				Name: "bar",
+				URLs: []string{"http://foo/bar"},
+			},
+		},
+		Branches: map[string]*Branch{
+			"bar": {
+				Name: "bar",
+			},
+			"foo": {
+				Name:   "foo",
+				Remote: "origin",
+				Merge:  plumbing.ReferenceName("refs/heads/foo"),
+			},
+		},
+	}
+
+	c.Assert(config.Validate(), IsNil)
+}
+
 func (s *ConfigSuite) TestValidateInvalidRemote(c *C) {
 	config := &Config{
 		Remotes: map[string]*RemoteConfig{
@@ -128,7 +164,7 @@ func (s *ConfigSuite) TestValidateInvalidRemote(c *C) {
 	c.Assert(config.Validate(), Equals, ErrRemoteConfigEmptyURL)
 }
 
-func (s *ConfigSuite) TestValidateInvalidKey(c *C) {
+func (s *ConfigSuite) TestValidateInvalidRemoteKey(c *C) {
 	config := &Config{
 		Remotes: map[string]*RemoteConfig{
 			"bar": {Name: "foo"},
@@ -157,10 +193,44 @@ func (s *ConfigSuite) TestRemoteConfigValidateDefault(c *C) {
 	c.Assert(fetch[0].String(), Equals, "+refs/heads/*:refs/remotes/foo/*")
 }
 
+func (s *ConfigSuite) TestValidateInvalidBranchKey(c *C) {
+	config := &Config{
+		Branches: map[string]*Branch{
+			"foo": {
+				Name:   "bar",
+				Remote: "origin",
+				Merge:  plumbing.ReferenceName("refs/heads/bar"),
+			},
+		},
+	}
+
+	c.Assert(config.Validate(), Equals, ErrInvalid)
+}
+
+func (s *ConfigSuite) TestValidateInvalidBranch(c *C) {
+	config := &Config{
+		Branches: map[string]*Branch{
+			"bar": {
+				Name:   "bar",
+				Remote: "origin",
+				Merge:  plumbing.ReferenceName("refs/heads/bar"),
+			},
+			"foo": {
+				Name:   "foo",
+				Remote: "origin",
+				Merge:  plumbing.ReferenceName("baz"),
+			},
+		},
+	}
+
+	c.Assert(config.Validate(), Equals, errBranchInvalidMerge)
+}
+
 func (s *ConfigSuite) TestRemoteConfigDefaultValues(c *C) {
 	config := NewConfig()
 
 	c.Assert(config.Remotes, HasLen, 0)
+	c.Assert(config.Branches, HasLen, 0)
 	c.Assert(config.Submodules, HasLen, 0)
 	c.Assert(config.Raw, NotNil)
 	c.Assert(config.Pack.Window, Equals, DefaultPackWindow)