Add better error handling for filesystem

server/filesystem/errors_test.go

@@ -1,13 +1,45 @@
 package filesystem
 
 import (
-	. "github.com/franela/goblin"
+	"io"
 	"testing"
+
+	"emperror.dev/errors"
+	. "github.com/franela/goblin"
 )
 
+type stackTracer interface {
+	StackTrace() errors.StackTrace
+}
+
 func TestFilesystem_PathResolutionError(t *testing.T) {
 	g := Goblin(t)
 
+	g.Describe("NewFilesystemError", func() {
+		g.It("includes a stack trace for the error", func() {
+			err := newFilesystemError(ErrCodeUnknownError, nil)
+
+			_, ok := err.(stackTracer)
+			g.Assert(ok).IsTrue()
+		})
+
+		g.It("properly wraps the underlying error cause", func() {
+			underlying := io.EOF
+			err := newFilesystemError(ErrCodeUnknownError, underlying)
+
+			_, ok := err.(stackTracer)
+			g.Assert(ok).IsTrue()
+
+			_, ok = err.(*Error)
+			g.Assert(ok).IsFalse()
+
+			fserr, ok := errors.Unwrap(err).(*Error)
+			g.Assert(ok).IsTrue()
+			g.Assert(fserr.Unwrap()).IsNotNil()
+			g.Assert(fserr.Unwrap()).Equal(underlying)
+		})
+	})
+
 	g.Describe("NewBadPathResolutionError", func() {
 		g.It("is can detect itself as an error correctly", func() {
 			err := NewBadPathResolution("foo", "bar")
@@ -18,6 +50,7 @@ func TestFilesystem_PathResolutionError(t *testing.T) {
 
 		g.It("returns <empty> if no destination path is provided", func() {
 			err := NewBadPathResolution("foo", "")
+			g.Assert(err).IsNotNil()
 			g.Assert(err.Error()).Equal("filesystem: server path [foo] resolves to a location outside the server root: <empty>")
 		})
 	})