add tests

Makes it *much* harder to accidentally break something.

coding_test.go

+package format
+
+import (
+	"errors"
+	"testing"
+
+	blocks "github.com/ipfs/go-block-format"
+	cid "github.com/ipfs/go-cid"
+	mh "github.com/multiformats/go-multihash"
+)
+
+func init() {
+	DefaultBlockDecoder[cid.Raw] = func(b blocks.Block) (Node, error) {
+		node := &EmptyNode{}
+		if b.RawData() != nil || !b.Cid().Equals(node.Cid()) {
+			return nil, errors.New("can only decode empty blocks")
+		}
+		return node, nil
+	}
+}
+
+func TestDecode(t *testing.T) {
+	id, err := cid.Prefix{
+		Version:  1,
+		Codec:    cid.Raw,
+		MhType:   mh.ID,
+		MhLength: 0,
+	}.Sum(nil)
+
+	if err != nil {
+		t.Fatalf("failed to create cid: %s", err)
+	}
+
+	block, err := blocks.NewBlockWithCid(nil, id)
+	if err != nil {
+		t.Fatalf("failed to create empty block: %s", err)
+	}
+	node, err := Decode(block)
+	if err != nil {
+		t.Fatalf("failed to decode empty node: %s", err)
+	}
+	if !node.Cid().Equals(id) {
+		t.Fatalf("empty node doesn't have the right cid")
+	}
+
+	if _, ok := node.(*EmptyNode); !ok {
+		t.Fatalf("empty node doesn't have the right type")
+	}
+
+}

format_test.go

+package format
+
+import (
+	"errors"
+	"testing"
+
+	cid "github.com/ipfs/go-cid"
+	mh "github.com/multiformats/go-multihash"
+)
+
+type EmptyNode struct{}
+
+var EmptyNodeError error = errors.New("dummy node")
+
+func (n *EmptyNode) Resolve([]string) (interface{}, []string, error) {
+	return nil, nil, EmptyNodeError
+}
+
+func (n *EmptyNode) Tree(string, int) []string {
+	return nil
+}
+
+func (n *EmptyNode) ResolveLink([]string) (*Link, []string, error) {
+	return nil, nil, EmptyNodeError
+}
+
+func (n *EmptyNode) Copy() Node {
+	return &EmptyNode{}
+}
+
+func (n *EmptyNode) Cid() *cid.Cid {
+	id, err := cid.Prefix{
+		Version:  1,
+		Codec:    cid.Raw,
+		MhType:   mh.ID,
+		MhLength: 0,
+	}.Sum(nil)
+
+	if err != nil {
+		panic("failed to create an empty cid!")
+	}
+	return id
+}
+
+func (n *EmptyNode) Links() []*Link {
+	return nil
+}
+
+func (n *EmptyNode) Loggable() map[string]interface{} {
+	return nil
+}
+
+func (n *EmptyNode) String() string {
+	return "[]"
+}
+
+func (n *EmptyNode) RawData() []byte {
+	return nil
+}
+
+func (n *EmptyNode) Size() (uint64, error) {
+	return 0, nil
+}
+
+func (n *EmptyNode) Stat() (*NodeStat, error) {
+	return &NodeStat{}, nil
+}
+
+func TestNodeType(t *testing.T) {
+	// Type assertion.
+	var _ Node = &EmptyNode{}
+}

package.json

@@ -9,15 +9,21 @@
   "gxDependencies": [
     {
       "author": "whyrusleeping",
-      "hash": "Qma4RJSuh7mMeJQYCqMbKzekn6EwBo7HEs5AQYjVRMQATB",
+      "hash": "QmTprEaAA2A9bst5XH7exuyi5KzNMK3SEDNN8rBDnKWcUS",
       "name": "go-cid",
-      "version": "0.7.16"
+      "version": "0.7.17"
     },
     {
       "author": "stebalien",
-      "hash": "QmXxGS5QsUxpR3iqL5DjmsYPHR1Yz74siRQ4ChJqWFosMh",
+      "hash": "QmVA4mafxbfH5aEvNz8fyoxC6J1xhAtw88B4GerPznSZBg",
       "name": "go-block-format",
-      "version": "0.1.2"
+      "version": "0.1.3"
+    },
+    {
+      "author": "multiformats",
+      "hash": "QmU9a9NV9RdPNwZQDYd5uKsm6N6LJLSvLbywDDYFbaaC6P",
+      "name": "go-multihash",
+      "version": "1.0.5"
     }
   ],
   "gxVersion": "0.10.0",