Fix error handling and get tests back to working

server/filesystem/errors_test.go

@@ -0,0 +1,24 @@
+package filesystem
+
+import (
+	. "github.com/franela/goblin"
+	"testing"
+)
+
+func TestFilesystem_PathResolutionError(t *testing.T) {
+	g := Goblin(t)
+
+	g.Describe("NewBadPathResolutionError", func() {
+		g.It("is can detect itself as an error correctly", func() {
+			err := NewBadPathResolution("foo", "bar")
+			g.Assert(IsBadPathResolutionError(err)).IsTrue()
+			g.Assert(err.Error()).Equal("filesystem: server path [foo] resolves to a location outside the server root: bar")
+			g.Assert(IsBadPathResolutionError(ErrIsDirectory)).IsFalse()
+		})
+
+		g.It("returns <empty> if no destination path is provided", func() {
+			err := NewBadPathResolution("foo", "")
+			g.Assert(err.Error()).Equal("filesystem: server path [foo] resolves to a location outside the server root: <empty>")
+		})
+	})
+}