Truncate the printed output when expect_equal_to_reference() fails

[jennybc]

I used expect_equal_to_reference() for a deeply nested list. When this test fails, it prints >1K lines of this form:

Component X: Component Y: target is blah, current is yo

[hadley]

Could you please provide a small reprex?

[jennybc]

library(testthat)
library(purrr)

x <- list(
  list(fruit = "apple", color = "red"),
  list(fruit = "grape", color = "green")
)

expect_equal_to_reference(x, "x.rds")

x <- x %>%
  map(function(x) {
    x$color <- sample(colors(), 1)
    x
  })
x
#> [[1]]
#> [[1]]$fruit
#> [1] "apple"
#> 
#> [[1]]$color
#> [1] "dodgerblue"
#> 
#> 
#> [[2]]
#> [[2]]$fruit
#> [1] "grape"
#> 
#> [[2]]$color
#> [1] "plum"

expect_equal_to_reference(x, "x.rds")
#> Error: `x` not equal to reference from `x.rds`.
#> Component 1: Component 2: 1 string mismatch
#> Component 2: Component 2: 1 string mismatch

I think you get one line of Component 2: Component 2: 1 string mismatch for every mismatch, no matter how many thousands there are.

My original context was roundtripping JSON: does the R object I get from httr::content() on a request match what I get after writing that list out to JSON and reading it back in. Apparently the answer is no and this is how I learned that. At very great length.