Test coverage for #215

[chainsawriot]

#215 reduces the test coverage by 9.6%.

https://app.codecov.io/gh/ropensci/readODS/tree/v2.4

For R, The missing lines are those about the added progress bar functions

https://app.codecov.io/gh/ropensci/readODS/blob/v2.4/R%2Fread_ods.R

For C++, the missing lines are those raised exceptions

https://app.codecov.io/gh/ropensci/readODS/blob/v2.4/src%2Fread_ods_.cpp

[chainsawriot]

C++ exceptions might have to be tested this way

readODS/tests/testthat/test_read_ods.R

Lines 16 to 21 in 5f4c107

	test_that("exceptions in C++ (hard to test)", {
	tempzip <- tempfile(fileext = ".zip")
	suppressWarnings(zip::zip(tempzip, "../testthat/test_read_ods.R"))
	expect_error(read_ods(tempzip), "is not a correct ODS file")
	expect_error(read_ods(path = "../testdata/sum.ods", sheet = -1), "Cannot have sheet index less than 1")
	})