Improvements to BDD (#1763)

* Export `it()` to make interactive testing easier. Fixes #1587.
* Call `use_test_context()` in `it()`. Fixes #1731

Adds rlang helpers which need a hack because of the old `is_null()` expectation.

Author: hadley

DESCRIPTION

@@ -33,7 +33,7 @@ Imports:
     processx,
     ps (>= 1.3.4),
     R6 (>= 2.2.0),
-    rlang (>= 1.0.1),
+    rlang (>= 1.1.0),
     utils,
     waldo (>= 0.4.0),
     withr (>= 2.4.3)

NAMESPACE

@@ -147,6 +147,7 @@ export(is_null)
 export(is_parallel)
 export(is_testing)
 export(is_true)
+export(it)
 export(local_edition)
 export(local_mock)
 export(local_mocked_bindings)

NEWS.md

@@ -1,5 +1,9 @@
 # testthat (development version)
 
+* `it()` now calls `local_test_context()` so that it behaves more
+  similarly to `test_that()` (#1731), and is now exported so that you
+  can more easily run BDD tests interactively (#1587)
+
 * `with_mocked_bindings()` and `local_mocked_bindings()` can now bind in the
   imports namespace too.
 

R/describe.R

@@ -56,32 +56,39 @@
 #' })
 
 describe <- function(description, code) {
-  is_invalid_description <- function(description) {
-    !is.character(description) || length(description) != 1 ||
-      nchar(description) == 0
-  }
-
-  if (is_invalid_description(description)) {
-    stop("description must be a string of at least length 1")
-  }
+  check_string(description, allow_empty = FALSE)
+  describe_description <- description
 
   # prepares a new environment for each it-block
   describe_environment <- new.env(parent = parent.frame())
-  describe_environment$it <- function(it_description, it_code = NULL) {
-    if (is_invalid_description(it_description)) {
-      stop("it-description must be a string of at least length 1")
-    }
-    if (missing(it_code)) return()
+  describe_environment$it <- function(description, code = NULL) {
+    check_string(description, allow_empty = FALSE)
+    code <- substitute(code)
 
-    test_description <- paste0(description, ": ", it_description)
-    test_code(
-      test_description,
-      substitute(it_code),
-      env = describe_environment,
-      skip_on_empty = FALSE
-    )
+    description <- paste0(describe_description, ": ", description)
+    describe_it(description, code, describe_environment)
   }
 
   eval(substitute(code), describe_environment)
   invisible()
 }
+
+describe_it <- function(description, code, env = parent.frame()) {
+  local_test_context()
+
+  test_code(
+    description,
+    code,
+    env = env,
+    skip_on_empty = FALSE
+  )
+}
+
+#' @export
+#' @rdname describe
+it <- function(description, code = NULL) {
+  check_string(description, allow_empty = FALSE)
+
+  code <- substitute(code)
+  describe_it(description, code)
+}