Make throttle testing more reliable with mocking (#538)

R/req-throttle.R

@@ -37,7 +37,7 @@ req_throttle <- function(req, rate, realm = NULL) {
     if (is.null(last)) {
       wait <- 0
     } else {
-      wait <- delay - (unix_time() - last)
+      wait <- max(delay - (unix_time() - last), 0)
     }
 
     sys_sleep(wait, "for throttling delay")

tests/testthat/test-req-throttle.R

@@ -2,18 +2,31 @@ test_that("first request isn't throttled", {
   skip_on_cran()
   throttle_reset()
 
-  req <- request_test() %>% req_throttle(50 / 1)
+  local_mocked_bindings(sys_sleep = function(...) {})
+  req <- request_test() %>% req_throttle(1)
+
+  local_mocked_bindings(unix_time = function() 0)
+  expect_equal(throttle_delay(req), 0)
+
+  local_mocked_bindings(unix_time = function() 0.1)
+  expect_equal(throttle_delay(req), 0.9)
+
+  local_mocked_bindings(unix_time = function() 1.5)
   expect_equal(throttle_delay(req), 0)
-  expect_true(throttle_delay(req) > 0)
 })
 
 test_that("throttling causes expected average request rate", {
   skip_on_cran()
   skip_on_ci()
   throttle_reset()
 
+  wait <- 0
+  local_mocked_bindings(sys_sleep = function(seconds, ...) {
+    wait <<- 0
+  })
+
   nps <- 20
-  req <- request_test() %>% req_throttle(nps)
+  req <- request_test() %>% req_throttle(20)
   times <- replicate(20, bench::system_time(req_perform(req)))["real", ]
   trimmed <- mean(times, trim = 0.2)