dplyr::all_equal() vs testthat::expect_equal() in testing

library(testthat)
library(dplyr, warn.conflicts = FALSE)

# expect_equal() returns silently if they're the same
expect_equal(iris, iris)

# but with an error if they're not
expect_equal(iris, mtcars)
#> Error: `iris` not equal to `mtcars`.
#> Names: 5 string mismatches
#> Attributes: < Component "row.names": Modes: numeric, character >
#> Attributes: < Component "row.names": target is numeric, current is character >
#> Length mismatch: comparison on first 5 components
#> Component 1: Numeric: lengths (150, 32) differ
#> Component 2: Numeric: lengths (150, 32) differ
#> Component 3: Numeric: lengths (150, 32) differ
#> Component 4: Numeric: lengths (150, 32) differ
#> Component 5: 'current' is not a factor

# Test will fail because iris != mtcars and expect_equal() will return an *error* saying so
test_that("iris is iris and mtcars isn't iris, using expect_equal", {
  expect_equal(iris, iris)
  expect_equal(iris, mtcars)
})
#> Error: Test failed: 'iris is iris and mtcars isn't iris, using expect_equal'
#> * `iris` not equal to `mtcars`.
#> Names: 5 string mismatches
#> Attributes: < Component "row.names": Modes: numeric, character >
#> Attributes: < Component "row.names": target is numeric, current is character >
#> Length mismatch: comparison on first 5 components
#> Component 1: Numeric: lengths (150, 32) differ
#> Component 2: Numeric: lengths (150, 32) differ
#> Component 3: Numeric: lengths (150, 32) differ
#> Component 4: Numeric: lengths (150, 32) differ
#> Component 5: 'current' is not a factor

# all_equal() returns TRUE if they're the same
all_equal(iris, iris)
#> [1] TRUE

# and just a description of what's not the same if they're not
all_equal(iris, mtcars)
#> [1] "Cols in y but not x: `carb`, `am`, `vs`, `qsec`, `hp`, `drat`, `gear`, `disp`, `cyl`, `wt`, `mpg`. "
#> [2] "Cols in x but not y: `Species`, `Petal.Width`, `Petal.Length`, `Sepal.Width`, `Sepal.Length`. "

# test passes even though iris != mtcars because all_equal() only returns a strings saying they're not equal
test_that("iris is iris and mtcars isn't iris, using all_equal", {
  all_equal(iris, iris)
  all_equal(iris, mtcars)
})