Extract helpers for expect_equals?

[hadley]

i.e. expect_attr_equal(), expect_element_equal(), expect_slot_equal().

This would let you do quick equality tests in a pipe for subcomponents. If you wanted to test for other things, you'd still need to manually extract

[hadley]

But this isn't particularly elegant because it requires special casing equality tests. You can almost already handle this problem with the tee pipe:

library(testthat)
library(magrittr)

x <- list(
  a = 1,
  b = 2
)

x %>%
  expect_type("list") %T>%
  {expect_equal(.$a, 1)} %T>%
  {expect_equal(.$b, 2)}

But it's not particularly elegant.

Ideally, the tree structure of the testing code would reflect the tree structure of the object.

[hadley]

Or maybe:

x %>%
  expect_type("list") %>%
  tee(
    expect_equal(.$a, 1), 
    expect_equal(.$b, 2)
  )

[krlmlr]

This looks very similar to what ensurer already does.

[krlmlr]

Also, wouldn't we want to use something like

x %>%
  expect_type("list") %>%
  tee(
    expect_equal(.data$a, 1), 
    expect_equal(.data$b, 2)
  )

(and optionally omit .data)?

[hadley]

I don't think so - tee() is very simple to implement if we rely on the existing magrittr semantics.