tests: Use elapsed time in timer tests (#232).

Compute actually elapsed time instead of assuming that usleep() sleeps
for exactly the right time, which isn't guaranteed.

tests/unit/unix_timer_tests.cc

@@ -1,13 +1,31 @@
+#include <chrono>
+#include <sstream>
+#include <thread>
+
 #include "gtest/gtest.h"
 #include "serial/impl/unix.h"
 
-#include <unistd.h>
-#include <stdlib.h>
-
 using serial::MillisecondTimer;
 
 namespace {
 
+typedef std::chrono::high_resolution_clock Clock;
+
+
+template <typename T>
+std::chrono::milliseconds as_milliseconds(T duration)
+{
+    return std::chrono::duration_cast<std::chrono::milliseconds>(duration);
+}
+
+
+struct test_timer {
+    MillisecondTimer timer;
+    std::chrono::time_point<Clock> start;
+    test_timer(unsigned value): start(Clock::now()), timer(value) {}
+};
+
+
 /**
  * Do 100 trials of timing gaps between 0 and 19 milliseconds.
  * Expect accuracy within one millisecond.
@@ -15,48 +33,45 @@ namespace {
 TEST(timer_tests, short_intervals) {
   for (int trial = 0; trial < 100; trial++)
   {
-    uint32_t ms = rand() % 20;
-    MillisecondTimer mt(ms);
-    usleep(1000 * ms);
-    int32_t r = mt.remaining(); 
-
-    // 1ms slush, for the cost of calling usleep.
-    EXPECT_NEAR(r+1, 0, 1);
+      int ms = rand() % 20;
+      auto t1 = Clock::now();
+      MillisecondTimer mt(ms);
+      std::this_thread::sleep_for(std::chrono::milliseconds(ms));
+      int elapsed = as_milliseconds(Clock::now() - t1).count();
+      EXPECT_NEAR(ms - elapsed, mt.remaining(), 1);
   }
 }
 
+
 TEST(timer_tests, overlapping_long_intervals) {
-  MillisecondTimer* timers[10];
 
-  // Experimentally determined. Corresponds to the extra time taken by the loops,
-  // the big usleep, and the test infrastructure itself.
-  const int slush_factor = 14;
+  std::vector<test_timer> timers;
 
-  // Set up the timers to each time one second, 1ms apart.
-  for (int t = 0; t < 10; t++)
-  {
-    timers[t] = new MillisecondTimer(1000);
-    usleep(1000);
+  // Set up the timers to each time one second, 1 ms apart.
+  while (timers.size() < 10) {
+    std::this_thread::sleep_for(std::chrono::milliseconds(1));
+    struct test_timer timer(1000);  // 1 s
+    timers.push_back(timer);
   }
 
-  // Check in on them after 500ms.
-  usleep(500000);
-  for (int t = 0; t < 10; t++)
-  {
-    EXPECT_NEAR(timers[t]->remaining(), 500 - slush_factor + t, 5);
+  // Check in on them after 500 ms.
+  std::this_thread::sleep_for(std::chrono::milliseconds(500));
+  for (auto& t: timers) {
+    auto elapsed = as_milliseconds(Clock::now() - t.start).count();
+    EXPECT_NEAR(1000 - elapsed, t.timer.remaining(), 1);
   }
 
-  // Check in on them again after another 500ms and free them.
-  usleep(500000);
-  for (int t = 0; t < 10; t++)
-  {
-    EXPECT_NEAR(timers[t]->remaining(), -slush_factor + t, 5);
-    delete timers[t];
+  // Check in on them again after another 500 ms.
+  std::this_thread::sleep_for(std::chrono::milliseconds(500));
+  for (auto& t: timers) {
+    auto elapsed = as_milliseconds(Clock::now() - t.start).count();
+    EXPECT_NEAR(1000 - elapsed, t.timer.remaining(), 1);
   }
 }
 
 }  // namespace
 
+
 int main(int argc, char **argv) {
   ::testing::InitGoogleTest(&argc, argv);
   return RUN_ALL_TESTS();

tests/unix_serial_tests.cc

@@ -20,8 +20,6 @@ void loop()
 #include <string>
 #include "gtest/gtest.h"
 
-#include <boost/bind.hpp>
-
 // Use FRIEND_TEST... its not as nasty, thats what friends are for
 // // OMG this is so nasty...
 // #define private public