[PATCH] testsuite: Fix instability in pytest-based tests

Hello-

This has been tested on sparc (cfarm216), where I often encounter the issue,
and also on x86-64 Linux. OK? Thanks!

-Lewis

-- >8 --

The python-based tests using the pytest library all call "expect" with the
default timeout, which is not always long enough for python to finish
importing everything and scanning the file system, especially on a slower
NFS mount. When the timeout is hit, it results in silently dropping the test
outputs. Resolve that by increasing the timeout and by reporting a FAIL upon
timeout to clarify what happened.

Additionally, in a frequently-used setup where the build directory and the
source directory are both contained in a common parent directory, pytest
ends up choosing that parent directory as its "root dir", and writes some
things there including a pytest_cache directory. When testing in parallel,
all parallel invocations use that same cache directory. I have not directly
seen it lead to an issue so far, but it is potentially problematic and it is
also surprising for users that pytest writes to a location outside of the
build directory. Address that as well by specifying the root dir to be
inside the test base_dir and disabling the cache, which is not needed in any
case.

gcc/testsuite/ChangeLog:

	* lib/target-supports.exp (pytest_invoke): New function.
	(check_effective_target_pytest3): Use pytest_invoke to add some
	additional arguments to the pytest invocation.
	* lib/gcov.exp (run-gcov-pytest): Set timeout to 300 seconds, report
	test failure upon timeout, and use new pytest_invoke helper.
	* lib/scanhtml.exp (run-html-pytest): Likewise.
	* lib/scansarif.exp (run-sarif-pytest): Likewise.
---
 gcc/testsuite/lib/gcov.exp            | 6 +++++-
 gcc/testsuite/lib/scanhtml.exp        | 7 +++++--
 gcc/testsuite/lib/scansarif.exp       | 7 +++++--
 gcc/testsuite/lib/target-supports.exp | 9 ++++++++-
 4 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/gcc/testsuite/lib/gcov.exp b/gcc/testsuite/lib/gcov.exp
index e62a39e7ed5..94a734817b1 100644
--- a/gcc/testsuite/lib/gcov.exp
+++ b/gcc/testsuite/lib/gcov.exp
@@ -694,9 +694,10 @@ proc run-gcov-pytest { args } {
     }
 
     setenv GCOV_PATH $testcase
-    spawn -noecho python3 -m pytest --color=no -rap -s --tb=no $srcdir/$subdir/$pytest_script
+    spawn -noecho {*}[pytest_invoke] $srcdir/$subdir/$pytest_script
 
     set prefix "\[^\r\n\]*"
+    set timeout 300
     expect {
       -re "FAILED($prefix)\[^\r\n\]+\r\n" {
        set output [gcov-pytest-format-line $testcase $pytest_script $expect_out(1,string)]
@@ -713,6 +714,9 @@ proc run-gcov-pytest { args } {
        pass $output
        exp_continue
       }
+      timeout {
+	  fail "$subdir/$testcase $pytest_script timed out"
+      }
     }
 
     clean-gcov $testcase
diff --git a/gcc/testsuite/lib/scanhtml.exp b/gcc/testsuite/lib/scanhtml.exp
index 9f2996c5530..d5aa20a2e1c 100644
--- a/gcc/testsuite/lib/scanhtml.exp
+++ b/gcc/testsuite/lib/scanhtml.exp
@@ -62,13 +62,14 @@ proc run-html-pytest { args } {
     
     verbose "PYTHONPATH=[getenv PYTHONPATH]" 2
 
-    spawn -noecho python3 -m pytest --color=no -rap -s --tb=no $srcdir/$subdir/$pytest_script
+    spawn -noecho {*}[pytest_invoke] $srcdir/$subdir/$pytest_script
 
     if [info exists old_PYTHONPATH] {
 	setenv PYTHONPATH ${old_PYTHONPATH}
     }
 
     set prefix "\[^\r\n\]*"
+    set timeout 300
     expect {
       -re "FAILED($prefix)\[^\r\n\]+\r\n" {
        set output [html-pytest-format-line $testcase $pytest_script $expect_out(1,string)]
@@ -85,6 +86,8 @@ proc run-html-pytest { args } {
        pass $output
        exp_continue
       }
+      timeout {
+	  fail "$subdir/$testcase $pytest_script timed out"
+      }
     }
 }
-
diff --git a/gcc/testsuite/lib/scansarif.exp b/gcc/testsuite/lib/scansarif.exp
index 03014cd7308..b96458e398f 100644
--- a/gcc/testsuite/lib/scansarif.exp
+++ b/gcc/testsuite/lib/scansarif.exp
@@ -173,13 +173,14 @@ proc run-sarif-pytest { args } {
     
     verbose "PYTHONPATH=[getenv PYTHONPATH]" 2
 
-    spawn -noecho python3 -m pytest --color=no -rap -s --tb=no $srcdir/$subdir/$pytest_script
+    spawn -noecho {*}[pytest_invoke] $srcdir/$subdir/$pytest_script
 
     if [info exists old_PYTHONPATH] {
 	setenv PYTHONPATH ${old_PYTHONPATH}
     }
 
     set prefix "\[^\r\n\]*"
+    set timeout 300
     expect {
       -re "FAILED($prefix)\[^\r\n\]+\r\n" {
        set output [sarif-pytest-format-line $testcase $pytest_script $expect_out(1,string)]
@@ -196,6 +197,8 @@ proc run-sarif-pytest { args } {
        pass $output
        exp_continue
       }
+      timeout {
+	  fail "$subdir/$testcase $pytest_script timed out"
+      }
     }
 }
-
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index eb2444204a0..bf49da5513a 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -14402,11 +14402,18 @@ proc check_effective_target_python3_module { module } {
     }]
 }
 
+# Helper to return the common pytest arguments
+proc pytest_invoke { } {
+    return [list python3 -m pytest --color=no -rap -s --tb=no \
+	    --rootdir . --basetemp pytest-tmp \
+	    -p no:cacheprovider]
+}
+
 # Return 1 if pytest module is available for python3.
 
 proc check_effective_target_pytest3 { } {
     return [check_cached_effective_target pytest3 {
-	set result [remote_exec host "python3 -m pytest --color=no -rap -s --tb=no --version"]
+	set result [remote_exec host "[pytest_invoke] --version"]
 	set status [lindex $result 0]
 	if { $status == 0 } then {
 	    return 1;