```
expect_setequal(letters, rev(letters))
show_failure(expect_setequal(letters[-1], rev(letters)))
x <- list(b = 2, a = 1)
expect_mapequal(x, list(a = 1, b = 2))
show_failure(expect_mapequal(x, list(a = 1)))
show_failure(expect_mapequal(x, list(a = 1, b = "x")))
show_failure(expect_mapequal(x, list(a = 1, b = 2, c = 3)))
```

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