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, 69 insertions, 0 deletions

diff --git a/plumbing/difftree/internal/merkletrie/frame_test.go b/plumbing/difftree/internal/merkletrie/frame_test.go
new file mode 100644
index 0000000..0ef036a
--- /dev/null
+++ b/plumbing/difftree/internal/merkletrie/frame_test.go
@@ -0,0 +1,69 @@
+package merkletrie
+
+import . "gopkg.in/check.v1"
+
+type FrameSuite struct{}
+
+var _ = Suite(&FrameSuite{})
+
+func (s *FrameSuite) TestNewFrameFromLeaf(c *C) {
+	n := newNode(
+		[]byte("hash"),
+		"key",
+		[]*node{},
+	)
+
+	frame := newFrame("foo", n)
+
+	expectedString := `base="foo/key", stack=[]`
+	c.Assert(frame.String(), Equals, expectedString)
+
+	obtainedTopNode, obtainedTopOK := frame.top()
+	c.Assert(obtainedTopNode, IsNil)
+	c.Assert(obtainedTopOK, Equals, false)
+
+	obtainedPopNode, obtainedPopOK := frame.top()
+	c.Assert(obtainedPopNode, IsNil)
+	c.Assert(obtainedPopOK, Equals, false)
+}
+
+func (s *FrameSuite) TestNewFrameFromParent(c *C) {
+	leaf0 := newNode([]byte("leaf0 hash"), "leaf0 key", []*node{})
+	leaf1 := newNode([]byte("leaf1 hash"), "leaf1 key", []*node{})
+	leaf2 := newNode([]byte("leaf2 hash"), "leaf2 key", []*node{})
+	leaf3 := newNode([]byte("leaf3 hash"), "leaf3 key", []*node{})
+	parent := newNode(
+		[]byte("parent hash"),
+		"parent key",
+		[]*node{leaf3, leaf0, leaf2, leaf1}, // not alphabetically sorted
+	)
+
+	frame := newFrame("foo", parent)
+
+	expectedString := `base="foo/parent key", stack=["leaf3 key", "leaf2 key", "leaf1 key", "leaf0 key"]`
+	c.Assert(frame.String(), Equals, expectedString)
+
+	checkTopAndPop(c, frame, leaf0, true)
+	checkTopAndPop(c, frame, leaf1, true)
+	checkTopAndPop(c, frame, leaf2, true)
+	checkTopAndPop(c, frame, leaf3, true)
+	checkTopAndPop(c, frame, nil, false)
+}
+
+func checkTopAndPop(c *C, f *frame, expectedNode *node, expectedOK bool) {
+	n, ok := f.top()
+	if expectedNode == nil {
+		c.Assert(n, IsNil)
+	} else {
+		c.Assert(n, DeepEquals, expectedNode)
+	}
+	c.Assert(ok, Equals, expectedOK)
+
+	n, ok = f.pop()
+	if expectedNode == nil {
+		c.Assert(n, IsNil)
+	} else {
+		c.Assert(n, DeepEquals, expectedNode)
+	}
+	c.Assert(ok, Equals, expectedOK)
+}