Merge pull request #103 from selkamand/99-calling-created-assertions-…

…without-any-arguments-makes-i

fix: assertions now provide informative errors when mandatory argumen…

R/assert_create.R

@@ -83,6 +83,10 @@ assert_create <- function(func, default_error_msg = NULL){
   # Create body of assertion function
   body = quote({
 
+    # Check mandatory arguments are all supplied
+    if(required_args_are_missing())
+      cli::cli_abort('mandatory argument/s were not supplied')
+
     # Setup some variables ( these will be useful later)
     if(is.null(arg_name))
       arg_name <- deparse(match.call()[[2]])

R/utils.R

@@ -110,3 +110,14 @@ func_arg_count <- function(func, dots = c("throw_error", "count_as_0", "count_as
 #   lgl <- unlist(args) == substitute()
 #   return(lgl)
 # }
+
+required_args_are_missing <- function (fun = sys.function(-1), ncall = 3) {
+  f_args <- formals(fun)
+  f_args <- f_args[vapply(f_args, is.symbol, FUN.VALUE = TRUE)]
+  f_args <- names(f_args)
+  f_args <- setdiff(f_args, "...")
+  test <- vapply(f_args,
+                 function(x) missingArg(as.name(x), envir = parent.frame(ncall), eval = TRUE),
+                 FUN.VALUE = TRUE)
+  return(any(test))
+}

tests/testthat/test-assert_create.R

@@ -110,7 +110,14 @@ cli::test_that_cli(configs = "plain", "assertion function works as expected with
   expect_snapshot(assert_between_min_and_max(2, min = 3, max = 5), error = TRUE)
 })
 
+cli::test_that_cli(configs = "plain", "created assertion() functions throw informative error when mandatory arguments are not supplied", {
+  f1 <- function(bob, billy) { return(TRUE) }
+  assert_f1 <- assertions::assert_create(f1, default_error_msg = 'this is an error message')
 
+  expect_error(assert_f1(), regexp = "mandatory argument/s were not supplied", fixed=TRUE)
+  expect_error(assert_f1(bob = 'a'), regexp = "mandatory argument/s were not supplied", fixed=TRUE)
+  expect_true(assert_f1('a', 'b'))
+})
 
 # Test Creation of Assertion Chains  -----------------------------------------------------
 cli::test_that_cli(configs = "plain", "assertion chains can evaluate expressions part and not get confused if they contain variable names", {