tests/testthat/test-20-extensions.R

In neuroconductor/RNifti: Fast R and C++ Access to NIfTI Images

test_that("NIfTI extensions can be written and read", {
    image <- readNifti(system.file("extdata", "example.nii.gz", package="RNifti"))
    comments <- c("A first comment", "A second comment")
    rawComments <- lapply(comments, function(x) structure(c(charToRaw(x), rep(as.raw(0L), 16 - (nchar(x)+8) %% 16)), code=6L))
    
    expect_equal(extensions(image), list())
    extension(image, "comment") <- comments[1]
    expect_equal(extensions(image), rawComments[1])
    expect_equal(extension(image,comment), rawComments[[1]])
    expect_equal(extension(image,"comment",mode="character"), comments[1])
    extension(image, comment) <- comments[2]
    expect_equal(extensions(image), rawComments)
    expect_equal(extension(image,"comment",mode="character"), as.list(comments))
})

test_that("NIfTI extensions persist through a write/read cycle", {
    image <- readNifti(system.file("extdata", "example.nii.gz", package="RNifti"), internal=TRUE)
    tempPath <- paste(tempfile(), "nii.gz", sep=".")
    
    comments <- c("A first comment", "A second comment")
    rawComments <- lapply(comments, function(x) structure(c(charToRaw(x), rep(as.raw(0L), 16 - (nchar(x)+8) %% 16)), code=6L))
    rawDouble <- writeBin(1000, raw())
    extensions <- c(rawComments, list(structure(rawDouble, code=20L)))
    
    extensions(image) <- rawComments
    extension(image, "b_value") <- 1000
    writeNifti(image, tempPath)
    rereadImage <- readNifti(tempPath)
    expect_equal(extensions(rereadImage), extensions)
})