Add expect_type

Fixes #316.

NAMESPACE

@@ -52,6 +52,7 @@ export(expect_output)
 export(expect_silent)
 export(expect_that)
 export(expect_true)
+export(expect_type)
 export(expect_warning)
 export(expectation)
 export(fail)

NEWS.md

@@ -1,5 +1,7 @@
 # testthat 0.11.0.9000
 
+* `expect_type()` checks the _type_ of the object (#316).
+
 * `not()` has been deprecated.
 
 * `MinimalReporter` correct labels errors with E and failures with F (#311).

R/expectations.r

@@ -1,9 +1,11 @@
-#' Expectation: does the object inherit from a class?
+#' Expectation: does the object inherit from a S3 or S4 class, or a base type?
 #'
-#' Tests whether or not an object inherits from any of a list of classes.
+#' Tests whether or not an object inherits from any of a list of classes, or
+#' is an instance of a base type.
 #'
 #' @inheritParams expect_that
 #' @param class character vector of class names
+#' @param type String giving base type (as returned by \code{\link{typeof}}).
 #' @seealso \code{\link{inherits}}
 #' @family expectations
 #' @export
@@ -36,6 +38,20 @@ is_a <- function(class) {
   }
 }
 
+#' @export
+#' @rdname expect_is
+expect_type <- function(expr, type) {
+  stopifnot(is.character(type), length(type) == 1)
+
+  label <- find_expr("expr")
+  actual_type <- typeof(expr)
+
+  expect(
+    identical(type, actual_type),
+    paste0("`", label, "` is type `", actual_type, "` not `", type, "`")
+  )
+}
+
 #' Expectation: is the object true/false?
 #'
 #' These are fall-back expectations that you can use when none of the other

tests/testthat/test-expectations.r

@@ -146,3 +146,8 @@ test_that("expected_named optionally ignores case", {
 test_that("expected_named optionally ignores order", {
   expect_named(c(a = 1, b = 2), c("b", "a"), ignore.order = TRUE)
 })
+
+
+test_that("expect_type checks typeof", {
+  expect_type(factor("a"), "integer")
+})