move plumbing from top level package to plumbing (#183)

* plumbing: rename Object -> EncodedObject.

* plumbing/storer: rename ObjectStorer -> EncodedObjectStorer.

* move difftree to plumbing/difftree.

* move diff -> utils/diff

* make Object/Tag/Blob/Tree/Commit/File depend on storer.

* Object and its implementations now depend only on
  storer.EncodedObjectStorer, not git.Repository.
* Tests are decoupled accordingly.

* move Object/Commit/File/Tag/Tree to plumbing/object.

* move Object/Commit/File/Tag/Tree to plumbing/object.
* move checkClose to utils/ioutil.

* move RevListObjects to plumbing/revlist.Objects.

* move DiffTree to plumbing/difftree package.

* rename files with plural nouns to singular

* plumbing/object: add GetBlob/GetCommit/GetTag/GetTree.

1 files changed, 430 insertions, 0 deletions

diff --git a/plumbing/difftree/difftree_test.go b/plumbing/difftree/difftree_test.go
new file mode 100644
index 0000000..c95e879
--- /dev/null
+++ b/plumbing/difftree/difftree_test.go
@@ -0,0 +1,430 @@
+package git
+
+import (
+	"sort"
+	"testing"
+
+	"gopkg.in/src-d/go-git.v4/fixtures"
+	"gopkg.in/src-d/go-git.v4/plumbing"
+	"gopkg.in/src-d/go-git.v4/plumbing/format/packfile"
+	"gopkg.in/src-d/go-git.v4/plumbing/object"
+	"gopkg.in/src-d/go-git.v4/plumbing/storer"
+	"gopkg.in/src-d/go-git.v4/storage/filesystem"
+	"gopkg.in/src-d/go-git.v4/storage/memory"
+
+	. "gopkg.in/check.v1"
+)
+
+func Test(t *testing.T) { TestingT(t) }
+
+type DiffTreeSuite struct {
+	fixtures.Suite
+	Storer  storer.EncodedObjectStorer
+	Fixture *fixtures.Fixture
+	cache   map[string]storer.EncodedObjectStorer
+}
+
+func (s *DiffTreeSuite) SetUpSuite(c *C) {
+	s.Suite.SetUpSuite(c)
+	s.Fixture = fixtures.Basic().One()
+	sto, err := filesystem.NewStorage(s.Fixture.DotGit())
+	c.Assert(err, IsNil)
+	s.Storer = sto
+	s.cache = make(map[string]storer.EncodedObjectStorer)
+}
+
+func (s *DiffTreeSuite) tree(c *C, h plumbing.Hash) *object.Tree {
+	t, err := object.GetTree(s.Storer, h)
+	c.Assert(err, IsNil)
+	return t
+}
+
+func (s *DiffTreeSuite) commitFromStorer(c *C, sto storer.EncodedObjectStorer,
+	h plumbing.Hash) *object.Commit {
+
+	commit, err := object.GetCommit(sto, h)
+	c.Assert(err, IsNil)
+	return commit
+}
+
+func (s *DiffTreeSuite) storageFromPackfile(f *fixtures.Fixture) storer.EncodedObjectStorer {
+	sto, ok := s.cache[f.URL]
+	if ok {
+		return sto
+	}
+
+	sto = memory.NewStorage()
+
+	pf := f.Packfile()
+
+	defer pf.Close()
+
+	n := packfile.NewScanner(pf)
+	d, err := packfile.NewDecoder(n, sto)
+	if err != nil {
+		panic(err)
+	}
+
+	_, err = d.Decode()
+	if err != nil {
+		panic(err)
+	}
+
+	s.cache[f.URL] = sto
+	return sto
+}
+
+var _ = Suite(&DiffTreeSuite{})
+
+func (s *DiffTreeSuite) TestActionString(c *C) {
+	expected := "Insert"
+	action := Insert
+	obtained := action.String()
+	c.Assert(obtained, Equals, expected)
+
+	expected = "Delete"
+	action = Delete
+	obtained = action.String()
+	c.Assert(obtained, Equals, expected)
+
+	expected = "Modify"
+	action = Modify
+	obtained = action.String()
+	c.Assert(obtained, Equals, expected)
+
+	action = 37
+	c.Assert(func() { _ = action.String() },
+		PanicMatches, "unsupported action: 37")
+}
+
+func (s *DiffTreeSuite) TestChangeFilesInsert(c *C) {
+	tree := s.tree(c, plumbing.NewHash("a8d315b2b1c615d43042c3a62402b8a54288cf5c"))
+
+	change := &Change{Action: Insert}
+	change.To.Name = "json/long.json"
+	change.To.Tree = tree
+	change.To.TreeEntry.Hash = plumbing.NewHash("49c6bb89b17060d7b4deacb7b338fcc6ea2352a9")
+
+	from, to, err := change.Files()
+	c.Assert(err, IsNil)
+	c.Assert(from, IsNil)
+	c.Assert(to.ID(), Equals, change.To.TreeEntry.Hash)
+}
+
+func (s *DiffTreeSuite) TestChangeFilesDelete(c *C) {
+	tree := s.tree(c, plumbing.NewHash("a8d315b2b1c615d43042c3a62402b8a54288cf5c"))
+
+	change := &Change{Action: Delete}
+	change.From.Name = "json/long.json"
+	change.From.Tree = tree
+	change.From.TreeEntry.Hash = plumbing.NewHash("49c6bb89b17060d7b4deacb7b338fcc6ea2352a9")
+
+	from, to, err := change.Files()
+	c.Assert(err, IsNil)
+	c.Assert(to, IsNil)
+	c.Assert(from.ID(), Equals, change.From.TreeEntry.Hash)
+}
+
+func (s *DiffTreeSuite) TestChangeFilesModify(c *C) {
+	tree := s.tree(c, plumbing.NewHash("a8d315b2b1c615d43042c3a62402b8a54288cf5c"))
+
+	change := &Change{Action: Modify}
+	change.To.Name = "json/long.json"
+	change.To.Tree = tree
+	change.To.TreeEntry.Hash = plumbing.NewHash("49c6bb89b17060d7b4deacb7b338fcc6ea2352a9")
+	change.From.Name = "json/long.json"
+	change.From.Tree = tree
+	change.From.TreeEntry.Hash = plumbing.NewHash("9a48f23120e880dfbe41f7c9b7b708e9ee62a492")
+
+	from, to, err := change.Files()
+	c.Assert(err, IsNil)
+	c.Assert(to.ID(), Equals, change.To.TreeEntry.Hash)
+	c.Assert(from.ID(), Equals, change.From.TreeEntry.Hash)
+}
+
+func (s *DiffTreeSuite) TestChangeString(c *C) {
+	expected := "<Action: Insert, Path: foo>"
+	change := &Change{Action: Insert}
+	change.From.Name = "foo"
+
+	obtained := change.String()
+	c.Assert(obtained, Equals, expected)
+}
+
+func (s *DiffTreeSuite) TestChangesString(c *C) {
+	expected := "[]"
+	changes := newEmpty()
+	obtained := changes.String()
+	c.Assert(obtained, Equals, expected)
+
+	expected = "[<Action: Modify, Path: bla>]"
+	changes = make([]*Change, 1)
+	changes[0] = &Change{Action: Modify}
+	changes[0].From.Name = "bla"
+
+	obtained = changes.String()
+	c.Assert(obtained, Equals, expected)
+
+	expected = "[<Action: Modify, Path: bla>, <Action: Insert, Path: foo/bar>]"
+	changes = make([]*Change, 2)
+	changes[0] = &Change{Action: Modify}
+	changes[0].From.Name = "bla"
+	changes[1] = &Change{Action: Insert}
+	changes[1].From.Name = "foo/bar"
+	obtained = changes.String()
+	c.Assert(obtained, Equals, expected)
+}
+
+type expectChange struct {
+	Action Action
+	Name   string
+}
+
+func (s *DiffTreeSuite) TestDiffTree(c *C) {
+	for i, t := range []struct {
+		repository string         // the repo name as in localRepos
+		commit1    string         // the commit of the first tree
+		commit2    string         // the commit of the second tree
+		expected   []expectChange // the expected list of []changeExpect
+	}{{
+		"https://github.com/dezfowler/LiteMock.git",
+		"",
+		"",
+		[]expectChange{},
+	}, {
+		"https://github.com/dezfowler/LiteMock.git",
+		"b7965eaa2c4f245d07191fe0bcfe86da032d672a",
+		"b7965eaa2c4f245d07191fe0bcfe86da032d672a",
+		[]expectChange{},
+	}, {
+		"https://github.com/dezfowler/LiteMock.git",
+		"",
+		"b7965eaa2c4f245d07191fe0bcfe86da032d672a",
+		[]expectChange{
+			{Action: Insert, Name: "README"},
+		},
+	}, {
+		"https://github.com/dezfowler/LiteMock.git",
+		"b7965eaa2c4f245d07191fe0bcfe86da032d672a",
+		"",
+		[]expectChange{
+			{Action: Delete, Name: "README"},
+		},
+	}, {
+		"https://github.com/githubtraining/example-branches.git",
+		"",
+		"f0eb272cc8f77803478c6748103a1450aa1abd37",
+		[]expectChange{
+			{Action: Insert, Name: "README.md"},
+		},
+	}, {
+		"https://github.com/githubtraining/example-branches.git",
+		"f0eb272cc8f77803478c6748103a1450aa1abd37",
+		"",
+		[]expectChange{
+			{Action: Delete, Name: "README.md"},
+		},
+	}, {
+		"https://github.com/githubtraining/example-branches.git",
+		"f0eb272cc8f77803478c6748103a1450aa1abd37",
+		"f0eb272cc8f77803478c6748103a1450aa1abd37",
+		[]expectChange{},
+	}, {
+		"https://github.com/github/gem-builder.git",
+		"",
+		"9608eed92b3839b06ebf72d5043da547de10ce85",
+		[]expectChange{
+			{Action: Insert, Name: "README"},
+			{Action: Insert, Name: "gem_builder.rb"},
+			{Action: Insert, Name: "gem_eval.rb"},
+		},
+	}, {
+		"https://github.com/github/gem-builder.git",
+		"9608eed92b3839b06ebf72d5043da547de10ce85",
+		"",
+		[]expectChange{
+			{Action: Delete, Name: "README"},
+			{Action: Delete, Name: "gem_builder.rb"},
+			{Action: Delete, Name: "gem_eval.rb"},
+		},
+	}, {
+		"https://github.com/github/gem-builder.git",
+		"9608eed92b3839b06ebf72d5043da547de10ce85",
+		"9608eed92b3839b06ebf72d5043da547de10ce85",
+		[]expectChange{},
+	}, {
+		"https://github.com/toqueteos/ts3.git",
+		"",
+		"764e914b75d6d6df1fc5d832aa9840f590abf1bb",
+		[]expectChange{
+			{Action: Insert, Name: "README.markdown"},
+			{Action: Insert, Name: "examples/bot.go"},
+			{Action: Insert, Name: "examples/raw_shell.go"},
+			{Action: Insert, Name: "helpers.go"},
+			{Action: Insert, Name: "ts3.go"},
+		},
+	}, {
+		"https://github.com/toqueteos/ts3.git",
+		"764e914b75d6d6df1fc5d832aa9840f590abf1bb",
+		"",
+		[]expectChange{
+			{Action: Delete, Name: "README.markdown"},
+			{Action: Delete, Name: "examples/bot.go"},
+			{Action: Delete, Name: "examples/raw_shell.go"},
+			{Action: Delete, Name: "helpers.go"},
+			{Action: Delete, Name: "ts3.go"},
+		},
+	}, {
+		"https://github.com/toqueteos/ts3.git",
+		"764e914b75d6d6df1fc5d832aa9840f590abf1bb",
+		"764e914b75d6d6df1fc5d832aa9840f590abf1bb",
+		[]expectChange{},
+	}, {
+		"https://github.com/github/gem-builder.git",
+		"9608eed92b3839b06ebf72d5043da547de10ce85",
+		"6c41e05a17e19805879689414026eb4e279f7de0",
+		[]expectChange{
+			{Action: Modify, Name: "gem_eval.rb"},
+		},
+	}, {
+		"https://github.com/github/gem-builder.git",
+		"6c41e05a17e19805879689414026eb4e279f7de0",
+		"89be3aac2f178719c12953cc9eaa23441f8d9371",
+		[]expectChange{
+			{Action: Modify, Name: "gem_eval.rb"},
+			{Action: Insert, Name: "gem_eval_test.rb"},
+			{Action: Insert, Name: "security.rb"},
+			{Action: Insert, Name: "security_test.rb"},
+		},
+	}, {
+		"https://github.com/github/gem-builder.git",
+		"89be3aac2f178719c12953cc9eaa23441f8d9371",
+		"597240b7da22d03ad555328f15abc480b820acc0",
+		[]expectChange{
+			{Action: Modify, Name: "gem_eval.rb"},
+		},
+	}, {
+		"https://github.com/github/gem-builder.git",
+		"597240b7da22d03ad555328f15abc480b820acc0",
+		"0260380e375d2dd0e1a8fcab15f91ce56dbe778e",
+		[]expectChange{
+			{Action: Modify, Name: "gem_eval.rb"},
+			{Action: Modify, Name: "gem_eval_test.rb"},
+			{Action: Insert, Name: "lazy_dir.rb"},
+			{Action: Insert, Name: "lazy_dir_test.rb"},
+			{Action: Modify, Name: "security.rb"},
+			{Action: Modify, Name: "security_test.rb"},
+		},
+	}, {
+		"https://github.com/github/gem-builder.git",
+		"0260380e375d2dd0e1a8fcab15f91ce56dbe778e",
+		"597240b7da22d03ad555328f15abc480b820acc0",
+		[]expectChange{
+			{Action: Modify, Name: "gem_eval.rb"},
+			{Action: Modify, Name: "gem_eval_test.rb"},
+			{Action: Delete, Name: "lazy_dir.rb"},
+			{Action: Delete, Name: "lazy_dir_test.rb"},
+			{Action: Modify, Name: "security.rb"},
+			{Action: Modify, Name: "security_test.rb"},
+		},
+	}, {
+		"https://github.com/github/gem-builder.git",
+		"0260380e375d2dd0e1a8fcab15f91ce56dbe778e",
+		"ca9fd470bacb6262eb4ca23ee48bb2f43711c1ff",
+		[]expectChange{
+			{Action: Modify, Name: "gem_eval.rb"},
+			{Action: Modify, Name: "security.rb"},
+			{Action: Modify, Name: "security_test.rb"},
+		},
+	}, {
+		"https://github.com/github/gem-builder.git",
+		"fe3c86745f887c23a0d38c85cfd87ca957312f86",
+		"b7e3f636febf7a0cd3ab473b6d30081786d2c5b6",
+		[]expectChange{
+			{Action: Modify, Name: "gem_eval.rb"},
+			{Action: Modify, Name: "gem_eval_test.rb"},
+			{Action: Insert, Name: "git_mock"},
+			{Action: Modify, Name: "lazy_dir.rb"},
+			{Action: Modify, Name: "lazy_dir_test.rb"},
+			{Action: Modify, Name: "security.rb"},
+		},
+	}, {
+		"https://github.com/rumpkernel/rumprun-xen.git",
+		"1831e47b0c6db750714cd0e4be97b5af17fb1eb0",
+		"51d8515578ea0c88cc8fc1a057903675cf1fc16c",
+		[]expectChange{
+			{Action: Modify, Name: "Makefile"},
+			{Action: Modify, Name: "netbsd_init.c"},
+			{Action: Modify, Name: "rumphyper_stubs.c"},
+			{Action: Delete, Name: "sysproxy.c"},
+		},
+	}, {
+		"https://github.com/rumpkernel/rumprun-xen.git",
+		"1831e47b0c6db750714cd0e4be97b5af17fb1eb0",
+		"e13e678f7ee9badd01b120889e0ec5fdc8ae3802",
+		[]expectChange{
+			{Action: Modify, Name: "app-tools/rumprun"},
+		},
+	}} {
+		f := fixtures.ByURL(t.repository).One()
+		sto := s.storageFromPackfile(f)
+
+		var tree1, tree2 *object.Tree
+		var err error
+		if t.commit1 != "" {
+			tree1, err = s.commitFromStorer(c, sto,
+				plumbing.NewHash(t.commit1)).Tree()
+			c.Assert(err, IsNil,
+				Commentf("subtest %d: unable to retrieve tree from commit %s and repo %s: %s", i, t.commit1, t.repository, err))
+		}
+
+		if t.commit2 != "" {
+			tree2, err = s.commitFromStorer(c, sto,
+				plumbing.NewHash(t.commit2)).Tree()
+			c.Assert(err, IsNil,
+				Commentf("subtest %d: unable to retrieve tree from commit %s and repo %s", i, t.commit2, t.repository, err))
+		}
+
+		obtained, err := DiffTree(tree1, tree2)
+		c.Assert(err, IsNil,
+			Commentf("subtest %d: unable to calculate difftree: %s", i, err))
+		c.Assert(equalChanges(obtained, t.expected), Equals, true,
+			Commentf("subtest:%d\nrepo=%s\ncommit1=%s\ncommit2=%s\nexpected=%s\nobtained=%s",
+				i, t.repository, t.commit1, t.commit2, t.expected, obtained))
+
+		assertChanges(obtained, c)
+	}
+}
+
+func assertChanges(a Changes, c *C) {
+	for _, changes := range a {
+		switch changes.Action {
+		case Insert:
+			c.Assert(changes.From.Tree, IsNil)
+			c.Assert(changes.To.Tree, NotNil)
+		case Delete:
+			c.Assert(changes.From.Tree, NotNil)
+			c.Assert(changes.To.Tree, IsNil)
+		case Modify:
+			c.Assert(changes.From.Tree, NotNil)
+			c.Assert(changes.To.Tree, NotNil)
+		}
+	}
+}
+
+func equalChanges(a Changes, b []expectChange) bool {
+	if len(a) != len(b) {
+		return false
+	}
+
+	sort.Sort(a)
+
+	for i, va := range a {
+		vb := b[i]
+		if va.Action != vb.Action || va.name() != vb.Name {
+			return false
+		}
+	}
+
+	return true
+}