bz-62890 fix the newly added test in SyncTest. Also, in the implementation of FileUtils#isCaseSensitiveFileSystem, take into account Files.isSame can throw NoSuchFileException in the absence of either of the paths being checked

src/main/org/apache/tools/ant/util/FileUtils.java

@@ -33,6 +33,7 @@ import java.net.URLConnection;
 import java.nio.channels.Channel;
 import java.nio.file.FileSystem;
 import java.nio.file.Files;
+import java.nio.file.NoSuchFileException;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.nio.file.StandardOpenOption;
@@ -1805,7 +1806,7 @@ public class FileUtils {
         }
         final String mixedCaseFileNamePrefix = "aNt";
         Path mixedCaseTmpFile = null;
-        final boolean caseSensitive;
+        boolean caseSensitive;
         try {
             synchronized (fileSystemCaseSensitivity) {
                 if (fileSystemCaseSensitivity.containsKey(fileSystem)) {
@@ -1823,7 +1824,14 @@ public class FileUtils {
                     return Optional.empty();
                 }
                 final Path lowerCasePath = Paths.get(mixedCaseTmpFile.toString().toLowerCase(Locale.US));
-                caseSensitive = !Files.isSameFile(mixedCaseTmpFile, lowerCasePath);
+                try {
+                    caseSensitive = !Files.isSameFile(mixedCaseTmpFile, lowerCasePath);
+                } catch (NoSuchFileException nsfe) {
+                    // a NSFE implies that the "lowerCasePath" file wasn't considered to be present
+                    // even if the different cased file exists. That effectively means this is a
+                    // case sensitive filesystem
+                    caseSensitive = true;
+                }
                 fileSystemCaseSensitivity.put(fileSystem, caseSensitive);
             }
         } catch (IOException ioe) {

src/tests/junit/org/apache/tools/ant/taskdefs/SyncTest.java

@@ -19,10 +19,14 @@
 package org.apache.tools.ant.taskdefs;
 
 import org.apache.tools.ant.BuildFileRule;
+import org.apache.tools.ant.util.FileUtils;
+import org.junit.Assume;
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
 
+import java.util.Optional;
+
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.not;
 import static org.junit.Assert.assertFalse;
@@ -147,7 +151,14 @@ public class SyncTest {
         buildRule.executeTarget("casesensitivity-test");
         final String destDir = buildRule.getProject().getProperty("dest") + "/casecheck";
         assertFileIsPresent(destDir + "/a.txt");
-        assertFileIsPresent(destDir + "/A.txt");
+        final boolean caseSensitive = FileUtils.isCaseSensitiveFileSystem(
+                buildRule.getProject().resolveFile(destDir).toPath())
+                .orElse(true); // directory scanner defaults to case sensitive = true
+        if (caseSensitive) {
+            assertFileIsNotPresent(destDir + "/A.txt");
+        } else {
+            assertFileIsPresent(destDir + "/A.txt");
+        }
         assertFileIsPresent(destDir + "/foo.txt");
 
         assertFileIsNotPresent(destDir + "/bar.txt");