CTest: Fix --test-load regression

The `ctest --test-load` option is implemented in `StartNextTests` by not
starting any tests when the load is too high and instead sleeping and
then returning.  Prior to commit v3.11.0-rc1~117^2 (CTest: Re-implement
test process handling using libuv, 2017-12-10) our outer loop in
`RunTests` would immediately call `StartNextTests` again.  However, now
the `uv_run` loop may simply terminate if there are no tests running
because no events are left pending.

Fix this by converting the sleep in `StartNextTests` into a libuv timer
that it starts instead.  This avoids leaving `uv_run` with no pending
events.  In the case that there are other running tests this also allows
CTest to detect when they finish even if it during the wait period where
we previously slept.

This regression was not caught by the test suite because it only
verified that we do not start new tests when the load was too high and
not that we proceed to start tests when the load drops.  Revise the test
suite to cover both.

Fixes: #18338

9 files changed, 20 insertions, 12 deletions

diff --git a/Tests/RunCMake/ctest_test/CTestTestLoadFail-result.txt b/Tests/RunCMake/ctest_test/CTestTestLoadFail-result.txt
deleted file mode 100644
index b57e2de..0000000
--- a/Tests/RunCMake/ctest_test/CTestTestLoadFail-result.txt
+++ /dev/null
@@ -1 +0,0 @@
-(-1|255)
diff --git a/Tests/RunCMake/ctest_test/CTestTestLoadFail-stderr.txt b/Tests/RunCMake/ctest_test/CTestTestLoadFail-stderr.txt
deleted file mode 100644
index eafba1c..0000000
--- a/Tests/RunCMake/ctest_test/CTestTestLoadFail-stderr.txt
+++ /dev/null
@@ -1 +0,0 @@
-No tests were found!!!
diff --git a/Tests/RunCMake/ctest_test/CTestTestLoadFail-stdout.txt b/Tests/RunCMake/ctest_test/CTestTestLoadFail-stdout.txt
deleted file mode 100644
index e203c10..0000000
--- a/Tests/RunCMake/ctest_test/CTestTestLoadFail-stdout.txt
+++ /dev/null
@@ -1,2 +0,0 @@
-Test project .*/Tests/RunCMake/ctest_test/CTestTestLoadFail-build
-\*\*\*\*\* WAITING, System Load: 5, Max Allowed Load: 4, Smallest test RunCMakeVersion requires 1\*\*\*\*\*$
diff --git a/Tests/RunCMake/ctest_test/CTestTestLoadWait-stdout.txt b/Tests/RunCMake/ctest_test/CTestTestLoadWait-stdout.txt
new file mode 100644
index 0000000..2af3838
--- /dev/null
+++ b/Tests/RunCMake/ctest_test/CTestTestLoadWait-stdout.txt
@@ -0,0 +1,8 @@
+Test project .*/Tests/RunCMake/ctest_test/CTestTestLoadWait-build
+\*\*\*\*\* WAITING, System Load: 5, Max Allowed Load: 4, Smallest test RunCMakeVersion requires 1\*\*\*\*\*
+    Start 1: RunCMakeVersion
+1/1 Test #1: RunCMakeVersion ..................   Passed +[0-9.]+ sec
++
+100% tests passed, 0 tests failed out of 1
++
+Total Test time \(real\) = +[0-9.]+ sec$
diff --git a/Tests/RunCMake/ctest_test/RunCMakeTest.cmake b/Tests/RunCMake/ctest_test/RunCMakeTest.cmake
index 1b31726..6877e6a 100644
--- a/Tests/RunCMake/ctest_test/RunCMakeTest.cmake
+++ b/Tests/RunCMake/ctest_test/RunCMakeTest.cmake
@@ -21,8 +21,8 @@ set(ENV{__CTEST_FAKE_LOAD_AVERAGE_FOR_TESTING} 5)
 run_ctest_test(TestLoadPass TEST_LOAD 6)
 
 # Verify that new tests are not started when the load average exceeds
-# our threshold.
-run_ctest_test(TestLoadFail TEST_LOAD 2)
+# our threshold and that they then run once the load average drops.
+run_ctest_test(TestLoadWait TEST_LOAD 2)
 
 # Verify that when an invalid "TEST_LOAD" value is given, a warning
 # message is displayed and the value is ignored.
@@ -34,9 +34,9 @@ set(CASE_CTEST_TEST_LOAD 7)
 run_ctest_test(CTestTestLoadPass)
 
 # Verify that new tests are not started when the load average exceeds
-# our threshold.
+# our threshold and that they then run once the load average drops.
 set(CASE_CTEST_TEST_LOAD 4)
-run_ctest_test(CTestTestLoadFail)
+run_ctest_test(CTestTestLoadWait)
 
 # Verify that when an invalid "CTEST_TEST_LOAD" value is given,
 # a warning message is displayed and the value is ignored.
diff --git a/Tests/RunCMake/ctest_test/TestLoadFail-result.txt b/Tests/RunCMake/ctest_test/TestLoadFail-result.txt
deleted file mode 100644
index b57e2de..0000000
--- a/Tests/RunCMake/ctest_test/TestLoadFail-result.txt
+++ /dev/null
@@ -1 +0,0 @@
-(-1|255)
diff --git a/Tests/RunCMake/ctest_test/TestLoadFail-stderr.txt b/Tests/RunCMake/ctest_test/TestLoadFail-stderr.txt
deleted file mode 100644
index eafba1c..0000000
--- a/Tests/RunCMake/ctest_test/TestLoadFail-stderr.txt
+++ /dev/null
@@ -1 +0,0 @@
-No tests were found!!!
diff --git a/Tests/RunCMake/ctest_test/TestLoadFail-stdout.txt b/Tests/RunCMake/ctest_test/TestLoadFail-stdout.txt
deleted file mode 100644
index 4d7ce48..0000000
--- a/Tests/RunCMake/ctest_test/TestLoadFail-stdout.txt
+++ /dev/null
@@ -1,2 +0,0 @@
-Test project .*/Tests/RunCMake/ctest_test/TestLoadFail-build
-\*\*\*\*\* WAITING, System Load: 5, Max Allowed Load: 2, Smallest test RunCMakeVersion requires 1\*\*\*\*\*$
diff --git a/Tests/RunCMake/ctest_test/TestLoadWait-stdout.txt b/Tests/RunCMake/ctest_test/TestLoadWait-stdout.txt
new file mode 100644
index 0000000..07f4ed3
--- /dev/null
+++ b/Tests/RunCMake/ctest_test/TestLoadWait-stdout.txt
@@ -0,0 +1,8 @@
+Test project .*/Tests/RunCMake/ctest_test/TestLoadWait-build
+\*\*\*\*\* WAITING, System Load: 5, Max Allowed Load: 2, Smallest test RunCMakeVersion requires 1\*\*\*\*\*
+    Start 1: RunCMakeVersion
+1/1 Test #1: RunCMakeVersion ..................   Passed +[0-9.]+ sec
++
+100% tests passed, 0 tests failed out of 1
++
+Total Test time \(real\) = +[0-9.]+ sec$