Avoid flaky tests with parallel execution

One test stores and deletes files named "-saved.xls", so
we need to prevent other tests from reading those

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1899077 13f79535-47bb-0310-9956-ffa450edef68

poi-integration/src/test/java/org/apache/poi/stress/TestAllFiles.java

@@ -136,6 +136,7 @@ public class TestAllFiles {
         final List<Arguments> result = new ArrayList<>(100);
         for (String file : scanner.getIncludedFiles()) {
 			// avoid running on files leftover from previous failed runs
+			// or being created by tests run in parallel
 			if(file.endsWith("-saved.xls") || file.endsWith("TestHPSFWritingFunctionality.doc")) {
 				continue;
 			}

poi/src/test/java/org/apache/poi/hssf/dev/BaseTestIteratingXLS.java

@@ -91,6 +91,14 @@ public abstract class BaseTestIteratingXLS {
     @ParameterizedTest
     @MethodSource("files")
     void testMain(File file, Class<? extends Throwable> t) throws Exception {
+        // avoid running files leftover from previous failed runs
+        // or created by tests running in parallel
+        // otherwise this would cause sporadic failures with
+        // parallel test execution
+        if(file.getName().endsWith("-saved.xls")) {
+            return;
+        }
+
         Executable ex = () -> runOneFile(file);
         if (t == null) {
             assertDoesNotThrow(ex);