fseval: not nanosecond for mock test

while testing on osx, it seems that it doesn't support nanoseconds so it
fails this check because the mockFsEval returns the nsec precision, but
the actual expected results is:

		        "old": "1337888911.288518233"
			"new": "1337888911.000000000"

Ideally there will be a way to detect when the fs supports nsecs

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

fseval_test.go

@@ -1,6 +1,7 @@
 package mtree
 
 import (
+	"encoding/json"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -8,7 +9,7 @@ import (
 	"time"
 )
 
-var mockTime = time.Unix(1337888823, 88288518233)
+var mockTime = time.Unix(1337888823, 0)
 
 // Here be some dodgy testing. In particular, we have to mess around with some
 // of the FsEval functions. In particular, we change all of the FileInfos to a
@@ -155,6 +156,11 @@ func TestCheckFsEval(t *testing.T) {
 		t.Fatal(err)
 	}
 	if len(res) > 0 {
+		buf, err := json.MarshalIndent(res, "", "  ")
+		if err != nil {
 			t.Errorf("%#v", res)
+		} else {
+			t.Errorf("%s", buf)
+		}
 	}
 }