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context("Extracting substrings")
alphabet <- str_c(letters, collapse = "")
test_that("correct substring extracted", {
expect_that(str_sub(alphabet, 1, 3), equals("abc"))
expect_that(str_sub(alphabet, 24, 26), equals("xyz"))
})
test_that("arguments expanded to longest", {
alphabet <- str_c(letters, collapse = "")
expect_that(
str_sub(alphabet, c(1, 24), c(3, 26)),
equals(c("abc", "xyz")))
expect_that(
str_sub(c("abc", "xyz"), 2, 2),
equals(c("b", "y")))
})
test_that("specifying only end subsets from start", {
expect_that(str_sub(alphabet, end = 3), equals(c("abc")))
})
test_that("specifying only start subsets to end", {
expect_that(str_sub(alphabet, 24), equals(c("xyz")))
})
test_that("specifying -1 as end selects entire string", {
expect_that(
str_sub("ABCDEF", c(4, 5), c(5, -1)),
equals(c("DE", "EF"))
)
expect_that(
str_sub("ABCDEF", c(4, 5), c(-1, -1)),
equals(c("DEF", "EF"))
)
})
test_that("negative values select from end", {
expect_that(str_sub("ABCDEF", 1, -4), equals("ABC"))
expect_that(str_sub("ABCDEF", -3), equals("DEF"))
})
test_that("missing arguments give missing results", {
expect_that(str_sub(NA), equals(NA_character_))
expect_that(str_sub(NA, 1, 3), equals(NA_character_))
expect_that(str_sub(c(NA, "NA"), 1, 3), equals(c(NA, "NA")))
expect_that(str_sub("test", NA, NA), equals(NA_character_))
expect_that(str_sub(c(NA, "test"), NA, NA), equals(rep(NA_character_, 2)))
})
test_that("replacement works", {
x <- "BBCDEF"
str_sub(x, 1, 1) <- "A"
expect_that(x, equals("ABCDEF"))
str_sub(x, -1, -1) <- "K"
expect_that(x, equals("ABCDEK"))
str_sub(x, -2, -1) <- "EFGH"
expect_that(x, equals("ABCDEFGH"))
str_sub(x, 2, -2) <- ""
expect_that(x, equals("AH"))
})
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