Ensure that expect_no_error() and friends pass when appropriate

Fixes #2037

Author: hadley

R/expect-no-condition.R

@@ -96,7 +96,10 @@ expect_no_ <- function(base_class,
 
   capture <- function(code) {
     try_fetch(
-      code,
+      {
+        code
+        NULL
+      },
       !!base_class := function(cnd) {
         if (!matcher(cnd)) {
           return(zap())

tests/testthat/test-expect-no-condition.R

@@ -13,10 +13,12 @@ test_that("expect_no_* conditions behave as expected", {
 })
 
 test_that("expect_no_* pass with pure code", {
-  expect_no_error(1)
-  expect_no_warning(1)
-  expect_no_message(1)
-  expect_no_condition(1)
+  expect_success(out <- expect_no_error(1))
+  expect_equal(out, 1)
+  
+  expect_success(expect_no_warning(1))
+  expect_success(expect_no_message(1))
+  expect_success(expect_no_condition(1))
 })
 
 test_that("expect_no_* don't emit success when they fail", {