Add new method "Is" in httperror.go

httperror.go

@@ -73,6 +73,20 @@ func (he *HTTPError) Error() string {
 	return fmt.Sprintf("code=%d, message=%v, err=%v", he.Code, msg, he.err.Error())
 }
 
+// Is checks if this error is equal to the target error.
+func (he *HTTPError) Is(target error) bool {
+	if he == target {
+		return true
+	}
+	switch t := target.(type) {
+	case *HTTPError:
+		return he.Code == t.Code
+	case *httpError:
+		return he.Code == t.code
+	}
+	return false
+}
+
 // Wrap eturns new HTTPError with given errors wrapped inside
 func (he HTTPError) Wrap(err error) error {
 	return &HTTPError{

httperror_test.go

@@ -65,3 +65,55 @@ func TestNewHTTPError(t *testing.T) {
 
 	assert.Equal(t, err2, err)
 }
+
+func TestHTTPError_Is(t *testing.T) {
+	var testCases = []struct {
+		name   string
+		err    *HTTPError
+		target error
+		expect bool
+	}{
+		{
+			name:   "ok, same instance",
+			err:    &HTTPError{Code: http.StatusNotFound},
+			target: &HTTPError{Code: http.StatusNotFound},
+			expect: true,
+		},
+		{
+			name:   "ok, different instance, same code",
+			err:    &HTTPError{Code: http.StatusNotFound},
+			target: &HTTPError{Code: http.StatusNotFound, Message: "different"},
+			expect: true,
+		},
+		{
+			name:   "ok, target is sentinel error",
+			err:    &HTTPError{Code: http.StatusNotFound},
+			target: ErrNotFound,
+			expect: true,
+		},
+		{
+			name:   "nok, different code",
+			err:    &HTTPError{Code: http.StatusNotFound},
+			target: &HTTPError{Code: http.StatusInternalServerError},
+			expect: false,
+		},
+		{
+			name:   "nok, target is sentinel error with different code",
+			err:    &HTTPError{Code: http.StatusNotFound},
+			target: ErrInternalServerError,
+			expect: false,
+		},
+		{
+			name:   "nok, target is different error type",
+			err:    &HTTPError{Code: http.StatusNotFound},
+			target: errors.New("some error"),
+			expect: false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			assert.Equal(t, tc.expect, errors.Is(tc.err, tc.target))
+		})
+	}
+}