Add failing test case for exists function.

CHANGELOG.md

@@ -1,3 +1,7 @@
+# Version 0.2.3.9002
+
+* Implement an `exists` method for `tracked_environment` objects.
+
 # Version 0.2.3.9001
 
  * Added an optimization to `replay` that avoids re-building an environment

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: objectdiff
 Type: Package
 Title: Objectdiff
-Version: 0.2.3.9001
+Version: 0.2.3.9002
 Description: Objectdiff is an R package for measuring differences
     between arbitrary R objects using patches, a la Git. For example,
     if you have slightly modified a data.frame, and you would like to
@@ -36,4 +36,4 @@ Collate:
     'patch.R'
     'squish.R'
     'utils.R'
-RoxygenNote: 5.0.1
+RoxygenNote: 5.0.1.9000

NAMESPACE

@@ -44,6 +44,7 @@ export(commit)
 export(commits)
 export(deletions)
 export(environment)
+export(exists)
 export(force_push)
 export(get)
 export(is.patch)

R/tracked_environment.R

@@ -77,6 +77,13 @@ rm <- function(..., envir = as.environment(-1)) {
     if (is.tracked_environment(envir)) environment(envir) else envir)
 }
 
+#' @export
+exists <- function(x, where = -1, envir = as.environment(-1), frame, mode = "any", inherits = TRUE) {
+  base::exists(x, where,
+               if (is.tracked_environment(envir)) environment(envir) else envir,
+               frame, mode, inherits)
+}
+
 #' @export
 as.environment <- function(...) UseMethod('as.environment')
 #' @method as.environment tracked_environment

tests/testthat/test-tracked_environment.R

@@ -167,3 +167,31 @@ test_that("it allows parent.env assignment", {
   expect_identical(parent.env(environment(x)), w)
 })
 
+test_that("it correctly uses the exists function", {
+  x <- tracked_environment(list2env(list(y = 1)))
+  expect_true(exists("y", envir = x))
+  expect_false(exists("z", envir = x))
+  expect_true(exists("y", env = x))
+  expect_false(exists("z", env = x))
+})
+
+test_that("it correctly uses the exists function with inherits = FALSE", {
+  x <- tracked_environment(list2env(list(y = 1), parent = list2env(list(z = 1))))
+  expect_true(exists("z", envir = x))
+  expect_false(exists("z", envir = x, inherits = FALSE))
+  expect_true(exists("z", env = x))
+  expect_false(exists("z", env = x, inherits = FALSE))
+})
+
+test_that("it correctly uses the exists function for vanilla environments", {
+  x <- list2env(list(y = 1), parent = list2env(list(z = 1)))
+  expect_true(exists("y", envir = x))
+  expect_false(exists("w", envir = x))
+  expect_true(exists("z", envir = x))
+  expect_false(exists("z", envir = x, inherits = FALSE))
+  expect_true(exists("y", env = x))
+  expect_false(exists("w", env = x))
+  expect_true(exists("z", env = x))
+  expect_false(exists("z", env = x, inherits = FALSE))
+})
+