1 files changed, 46 insertions, 0 deletions
diff --git a/tests/emscripten_get_now.cpp b/tests/emscripten_get_now.cpp
new file mode 100644
index 00000000..17aa7d32
--- /dev/null
+++ b/tests/emscripten_get_now.cpp
@@ -0,0 +1,46 @@
+#include <stdio.h>
+#include "emscripten.h"
+
+#ifndef REPORT_RESULT
+// To be able to run this test outside the browser harness in node.js/spidermonkey:
+#define REPORT_RESULT int dummy
+#endif
+
+int result = 0;
+
+int main() {
+  // This code tests three things:
+  // a) Calling emscripten_get_now(), time actually proceeds.
+  // b) Values returned by emscripten_get_now() are strictly nondecreasing.
+  // c) emscripten_get_now() is able to return sub-millisecond precision timer values.
+  bool detected_good_timer_precision = false;
+  float smallest_delta = 0.f;
+  for(int x = 0; x < 1000; ++x) { // Have several attempts to find a good small delta, i.e. give time to JS engine to warm up the code and so on.
+    float t = emscripten_get_now();
+    float t2 = emscripten_get_now();
+    for(int i = 0; i < 100 && t == t2; ++i) {
+      t2 = emscripten_get_now();
+    }
+
+    if (t2 < t && t2 - t < 1000.f) { // Timer must be monotonous.
+      printf("Timer is not monotonous!\\n");
+      smallest_delta = t2 - t;
+      break;
+    }
+    if (t2 > t && t2 - t < 0.7f) { // Must pass less than a millisecond between two calls.
+      detected_good_timer_precision = true;
+      smallest_delta = t2 - t;
+      break;
+    }
+  }
+  
+  if (detected_good_timer_precision) {
+    printf("Timer resolution is good. (%f msecs)\\n", smallest_delta);
+    result = 1;
+  } else {
+    printf("Error: Bad timer precision: Smallest timer delta: %f msecs\\n", smallest_delta);
+    result = 0;
+  }
+  REPORT_RESULT();
+  return 0;
+}