Apply some IDE suggestions, add tests, set unit-test to isolated

Without Isolation, one test did change static settings 
and thus could cause flaky tests

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1911891 13f79535-47bb-0310-9956-ffa450edef68

2 files changed, 8 insertions, 0 deletions

diff --git a/poi-ooxml/src/test/java/org/apache/poi/openxml4j/TestOPCPackageFileLimit.java b/poi-ooxml/src/test/java/org/apache/poi/openxml4j/TestOPCPackageFileLimit.java
index 017de0a10e..02f81ccd51 100644
--- a/poi-ooxml/src/test/java/org/apache/poi/openxml4j/TestOPCPackageFileLimit.java
+++ b/poi-ooxml/src/test/java/org/apache/poi/openxml4j/TestOPCPackageFileLimit.java
@@ -22,6 +22,7 @@ import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
 import org.apache.poi.openxml4j.opc.OPCPackage;
 import org.apache.poi.openxml4j.util.ZipSecureFile;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.parallel.Isolated;
 
 import java.io.File;
 import java.io.IOException;
@@ -30,6 +31,7 @@ import java.io.InputStream;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 
+@Isolated // changes static values, so other tests should not run at the same time
 class TestOPCPackageFileLimit {
     @Test
     void testWithReducedFileLimit() throws InvalidFormatException {
diff --git a/poi-ooxml/src/test/java/org/apache/poi/xssf/eventusermodel/TestReadOnlySharedStringsTable.java b/poi-ooxml/src/test/java/org/apache/poi/xssf/eventusermodel/TestReadOnlySharedStringsTable.java
index be486270ed..220963db79 100644
--- a/poi-ooxml/src/test/java/org/apache/poi/xssf/eventusermodel/TestReadOnlySharedStringsTable.java
+++ b/poi-ooxml/src/test/java/org/apache/poi/xssf/eventusermodel/TestReadOnlySharedStringsTable.java
@@ -67,6 +67,12 @@ public final class TestReadOnlySharedStringsTable {
                     assertEquals(i1.getString(), rtbl.getItemAt(i).getString());
                     assertEquals(i1.getString(), rtbl2.getItemAt(i).getString());
                 }
+
+                // verify invalid indices
+                assertThrows(IllegalStateException.class,
+                        () -> rtbl.getItemAt(stbl.getUniqueCount()));
+                assertThrows(IndexOutOfBoundsException.class,
+                        () -> rtbl.getItemAt(-1));
             }
         }
     }