Allow test event loop dispatch time adjustment for slow VMs (#37210)

* Allow event loop dispatch time adjustment for slow VMs

* Restyled by clang-format

---------

Co-authored-by: Restyled.io <[email protected]>

Author: arkq

src/system/tests/TestEventLoopHandler.cpp

@@ -14,6 +14,10 @@
  *    limitations under the License.
  */
 
+#include <cstdlib>
+#include <functional>
+#include <string>
+
 #include <pw_unit_test/framework.h>
 #include <system/SystemConfig.h>
 
@@ -25,9 +29,6 @@
 #include <lib/support/CodeUtils.h>
 #include <platform/CHIPDeviceLayer.h>
 
-#include <functional>
-#include <string>
-
 using namespace chip;
 using namespace chip::System::Clock;
 using namespace chip::System::Clock::Literals;
@@ -139,9 +140,20 @@ TEST_F(TestEventLoopHandler, EventLoopHandlerWake)
     SystemLayer().RemoveLoopHandler(loopHandler);
     cancelFallback(); // avoid leaking the fallback timer
 
+    // Get the upper bound of the sleep duration from the environment, so we can
+    // adjust it if the test machine is under heavy load, e.g. in CI or on a slow VM.
+    // By default, we expect the sleep duration to be close to the requested 400ms.
+    unsigned int expectedMaxDuration = 500u; // allow some slack for test machine load
+    const char * maxDurationEnv      = std::getenv("CHIP_TEST_EVENT_LOOP_HANDLER_MAX_DURATION_MS");
+    if (maxDurationEnv != nullptr)
+    {
+        ChipLogDetail(Test, "CHIP_TEST_EVENT_LOOP_HANDLER_MAX_DURATION_MS=%s", maxDurationEnv);
+        expectedMaxDuration = static_cast<unsigned int>(std::stoul(maxDurationEnv));
+    }
+
     Timestamp sleepDuration = loopHandler.wakeTimestamp - loopHandler.startTimestamp;
     EXPECT_GE(sleepDuration.count(), 400u); // loopHandler requested wake-up after 400ms
-    EXPECT_LE(sleepDuration.count(), 500u); // allow some slack for test machine load
+    EXPECT_LE(sleepDuration.count(), expectedMaxDuration);
 }
 
 #endif // !CHIP_DEVICE_LAYER_TARGET_FAKE

src/test_driver/tizen/chip_tests/runner.sh

@@ -21,6 +21,9 @@ set -e
 # Print CHIP logs on stdout
 dlogutil CHIP &
 
+# Override the default value to account for slower execution on QEMU.
+export CHIP_TEST_EVENT_LOOP_HANDLER_MAX_DURATION_MS=1000
+
 # Set the correct path for .gcda files
 export GCOV_PREFIX=/mnt/chip
 export GCOV_PREFIX_STRIP=5