NOISSUE : Revert removal of errors Unwrap function (#3299)

Signed-off-by: Felix Gateru <felix.gateru@gmail.com>

pkg/errors/errors.go

@@ -98,6 +98,21 @@ func Wrap(wrapper, err error) error {
 	}
 }
 
+// Unwrap returns the wrapper and the error by separating the Wrapper from the error.
+func Unwrap(err error) (error, error) {
+	if err == nil {
+		return nil, nil
+	}
+	if ce, ok := err.(Error); ok {
+		if ce.Err() == nil {
+			return nil, New(ce.Msg())
+		}
+		return New(ce.Msg()), ce.Err()
+	}
+
+	return nil, err
+}
+
 func cast(err error) Error {
 	if err == nil {
 		return nil

pkg/errors/errors_test.go

@@ -276,6 +276,56 @@ func TestWrap(t *testing.T) {
 	}
 }
 
+func TestUnwrap(t *testing.T) {
+	cases := []struct {
+		desc    string
+		err     error
+		wrapper error
+		wrapped error
+	}{
+		{
+			desc:    "err 1 wraped err 2",
+			err:     errors.Wrap(err1, err2),
+			wrapper: err2,
+			wrapped: fmt.Errorf("%w: %w", err2, err1),
+		},
+		{
+			desc:    "nil wraps nil",
+			err:     errors.Wrap(nil, nil),
+			wrapper: nil,
+			wrapped: nil,
+		},
+		{
+			desc:    "nil wraps err0",
+			err:     errors.Wrap(nil, err0),
+			wrapper: nil,
+			wrapped: nil,
+		},
+		{
+			desc:    "nil wraps native error",
+			err:     errors.Wrap(nil, nat),
+			wrapper: nil,
+			wrapped: nil,
+		},
+		{
+			desc:    "native error wraps nil",
+			err:     errors.Wrap(nat, nil),
+			wrapper: nil,
+			wrapped: nat,
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.desc, func(t *testing.T) {
+			wrapper, wrapped := errors.Unwrap(c.err)
+			assert.Equal(t, c.wrapper, wrapper)
+			if c.wrapped != nil {
+				assert.Equal(t, c.wrapped.Error(), wrapped.Error())
+			}
+		})
+	}
+}
+
 func wrap(level int) error {
 	if level == 0 {
 		return errors.New(strconv.Itoa(level))