Give more informative message with `expect_named()`

[EmilHvitfeldt]

Currently expect_identical() gives a much more informative error when some is wrong compared to expect_named()

library(testthat)

x <- list(a = 1, b = 2, d = 3)

expect_identical(names(x), c("a", "b", "c"))
#> Error: names(x) not identical to c("a", "b", "c").
#> 1/3 mismatches
#> x[3]: "d"
#> y[3]: "c"
expect_named(x, c("a", "b", "c"))
#> Error: Names of `x` ('a', 'b', 'd') don't match 'a', 'b', 'c'

^{Created on 2025-07-01 with reprex v2.1.1}

[hadley]

Hmmm, the problem is that you might be using expect_named() with ignore.order = TRUE, so we can't change it in general. But maybe we could do better in the default case?

[EmilHvitfeldt]

hmm something similar could be done in the ignore.order = TRUE, but more custom. You only have problems, "in object, not in expected" and "in expected, not in object"

library(testthat)

x <- setNames(nm = 1:100)

expect_named(x, as.character(c(1:56, 58:100)), ignore.order = TRUE)
#> Error: Names of `x` ('1', '10', '100', '11', '12', '13', '14', '15', '16', '17', '18', '19', 
#> '2', '20', '21', '22', '23', '24', '25', '26', '27', '28', '29', '3', '30', '31', '32', '33', 
#> '34', '35', '36', '37', '38', '39', '4', '40', '41', '42', '43', '44', '45', '46', '47', '48', 
#> '49', '5', '50', '51', '52', '53', '54', '55', '56', '57', '58', '59', '6', '60', '61', '62',
#>  '63', '64', '65', '66', '67', '68', '69', '7', '70', '71', '72', '73', '74', '75', '76', '77', 
#> '78', '79', '8', '80', '81', '82', '83', '84', '85', '86', '87', '88', '89', '9', '90', '91', 
#> '92', '93', '94', '95', '96', '97', '98', '99') don't match '1', '10', '100', '11', '12', 
#> '13', '14', '15', '16', '17', '18', '19', '2', '20', '21', '22', '23', '24', '25', '26', '27', 
#> '28', '29', '3', '30', '31', '32', '33', '34', '35', '36', '37', '38', '39', '4', '40', '41', 
#> '42', '43', '44', '45', '46', '47', '48', '49', '5', '50', '51', '52', '53', '54', '55', '56', 
#> '58', '59', '6', '60', '61', '62', '63', '64', '65', '66', '67', '68', '69', '7', '70', '71', 
#> '72', '73', '74', '75', '76', '77', '78', '79', '8', '80', '81', '82', '83', '84', '85', '86',
#>  '87', '88', '89', '9', '90', '91', '92', '93', '94', '95', '96', '97', '98', '99'

^{Created on 2025-07-16 with reprex v2.1.1}

(don't mind the wonky formatting and wording)

#> Error: names of `x` doesn't match expectation.
#> Not expected:`57`

[EmilHvitfeldt]

if you think it is a worthwhile change i would be happy to contribute

[hadley]

Oh yeah, that makes sense. Maybe we could reuse some of the code from expect_contains()?