Add another skip()

Author: jennybc

tests/testthat/test-expect-inheritance.R

@@ -132,5 +132,6 @@ test_that("can check with actual class", {
 })
 
 test_that("expect_s7_class validates its inputs", {
+  skip_if_not_installed("S7")
   expect_snapshot(expect_s7_class(1, 1), error = TRUE)
 })