Ensure writing deptree works for bzr, hg

The main fix here is avoiding creating an empty directory for the
destination, as copyDir() doesn't like that. Instead, we create only
up to the parent dir.

The other bit is ensuring the source repos exist in the cache before
attempting to export them, for both bzr and hg.

Addresses golang/dep#144

Author: sdboyer

result.go

@@ -48,7 +48,9 @@ func WriteDepTree(basedir string, l Lock, sm SourceManager, sv bool) error {
 	for _, p := range l.Projects() {
 		to := path.Join(basedir, string(p.Ident().ProjectRoot))
 
-		err := os.MkdirAll(to, 0777)
+		// Only make the parent dir, as some source implementations will balk on
+		// trying to write to an empty but existing dir.
+		err := os.MkdirAll(filepath.Dir(to), 0777)
 		if err != nil {
 			return err
 		}

result_test.go

@@ -1,8 +1,10 @@
 package gps
 
 import (
+	"io/ioutil"
 	"os"
 	"path"
+	"path/filepath"
 	"testing"
 )
 
@@ -43,26 +45,54 @@ func TestWriteDepTree(t *testing.T) {
 		t.Skip("Skipping dep tree writing test in short mode")
 	}
 
-	r := basicResult
+	tmp, err := ioutil.TempDir("", "writetree")
+	if err != nil {
+		t.Errorf("Failed to create temp dir: %s", err)
+		t.FailNow()
+	}
+	defer os.RemoveAll(tmp)
 
-	tmp := path.Join(os.TempDir(), "vsolvtest")
-	os.RemoveAll(tmp)
+	r := solution{
+		att: 1,
+		p: []LockedProject{
+			pa2lp(atom{
+				id: pi("github.com/sdboyer/testrepo"),
+				v:  NewBranch("master").Is(Revision("4d59fb584b15a94d7401e356d2875c472d76ef45")),
+			}, nil),
+			pa2lp(atom{
+				id: pi("launchpad.net/govcstestbzrrepo"),
+				v:  NewVersion("1.0.0").Is(Revision("[email protected]")),
+			}, nil),
+			pa2lp(atom{
+				id: pi("bitbucket.org/sdboyer/withbm"),
+				v:  NewVersion("v1.0.0").Is(Revision("aa110802a0c64195d0a6c375c9f66668827c90b4")),
+			}, nil),
+		},
+	}
 
 	sm, clean := mkNaiveSM(t)
 	defer clean()
 
 	// nil lock/result should err immediately
-	err := WriteDepTree(path.Join(tmp, "export"), nil, sm, true)
+	err = WriteDepTree(tmp, nil, sm, true)
 	if err == nil {
 		t.Errorf("Should error if nil lock is passed to WriteDepTree")
 	}
 
-	err = WriteDepTree(path.Join(tmp, "export"), r, sm, true)
+	err = WriteDepTree(tmp, r, sm, true)
 	if err != nil {
 		t.Errorf("Unexpected error while creating vendor tree: %s", err)
 	}
 
-	// TODO(sdboyer) add more checks
+	if _, err = os.Stat(filepath.Join(tmp, "github.com", "sdboyer", "testrepo")); err != nil {
+		t.Errorf("Directory for github.com/sdboyer/testrepo does not exist")
+	}
+	if _, err = os.Stat(filepath.Join(tmp, "launchpad.net", "govcstestbzrrepo")); err != nil {
+		t.Errorf("Directory for launchpad.net/govcstestbzrrepo does not exist")
+	}
+	if _, err = os.Stat(filepath.Join(tmp, "bitbucket.org", "sdboyer", "withbm")); err != nil {
+		t.Errorf("Directory for bitbucket.org/sdboyer/withbm does not exist")
+	}
 }
 
 func BenchmarkCreateVendorTree(b *testing.B) {

source.go

@@ -432,5 +432,8 @@ func (bs *baseVCSSource) toRevOrErr(v Version) (r Revision, err error) {
 }
 
 func (bs *baseVCSSource) exportVersionTo(v Version, to string) error {
+	if err := bs.ensureCacheExistence(); err != nil {
+		return err
+	}
 	return bs.crepo.exportVersionTo(v, to)
 }