Simplify tidyr::separate.soma_adat() S3 method

- simplified code using `%||%`
- added expeanded error messages inside `stopifnot()`
- minor fix of unit test syntax
- fixes #72

R/tidyr-verbs.R

@@ -9,13 +9,12 @@ separate.soma_adat <- function(data, col, into, sep = "[^[:alnum:]]+",
                                fill = "warn", ...) {
   atts <- attributes(data)
   data <- rn2col(data, ".separate_rn")
-  # must do it this way b/c NextMethod() doesn't play nice with tidyeval
-  col2 <- tryCatch(col, error = function(e) NULL) # NULL if 'col' is lazyeval
-  if ( is.null(col2) ) col2 <- deparse(substitute(col))
+  # must do it this way b/c NextMethod() doesn't play nice with lazyeval
+  col2 <- tryCatch(eval(col), error = function(e) NULL) %||% deparse(substitute(col))
   stopifnot(
-    length(col2) == 1L,
-    is.character(col2),
-    col2 %in% names(data)
+    "`col` must be a `character(1)` or a symbol." = is.character(col2),
+    "`col` must have length = 1." = length(col2) == 1L,
+    "`col` must be a variable name in `data`." = col2 %in% names(data)
   )
   data  <- data.frame(data)
   .data <- tidyr::separate(data, col2, into, sep, remove, convert, extra, fill, ...)

tests/testthat/test-tidyr-verbs.R

@@ -1,7 +1,7 @@
 
 # Setup ----
 data   <- mock_adat()
-data$a <- LETTERS[1:6]
+data$a <- LETTERS[1:6L]
 data$d <- as.character(1:6)
 data$b <- paste0(data$a, "-", data$d)
 
@@ -12,7 +12,7 @@ test_that("separate() method produces expected output", {
   expect_s3_class(new, "soma_adat")
   expect_true(is_intact_attr(new))
   expect_equal(class(new), class(data))
-  expect_equal(dim(new), dim(data) + c(0, 1))   # 1 new column
+  expect_equal(dim(new), dim(data) + c(0, 1L))   # 1 new column
   expect_true("c" %in% names(new))
   expect_true("b" %in% names(new))
   expect_equal(rownames(new), rownames(data))
@@ -36,7 +36,7 @@ test_that("unite() method produces expected output", {
   expect_s3_class(new, "soma_adat")
   expect_true(is_intact_attr(new))
   expect_equal(class(new), class(data))
-  expect_equal(dim(new), dim(data) + c(0, -1))   # 1 less column
+  expect_equal(dim(new), dim(data) + c(0, -1L))   # 1 less column
   expect_true("combo" %in% names(new))
   expect_false("a" %in% names(new))
   expect_false("d" %in% names(new))