[FIXED JENKINS-17271] Util.deleteFile should give a concrete reason for failure.

core/src/test/java/hudson/UtilTest.java

@@ -37,6 +37,9 @@ import org.junit.Test;
 import org.jvnet.hudson.test.Bug;
 
 import hudson.util.StreamTaskListener;
+import java.io.FileOutputStream;
+import java.io.OutputStream;
+import org.junit.internal.AssumptionViolatedException;
 
 /**
  * @author Kohsuke Kawaguchi
@@ -230,6 +233,31 @@ public class UtilTest {
         }
     }
 
+    @Test public void deleteFile() throws Exception {
+        Assume.assumeTrue(Functions.isWindows());
+        Class<?> c;
+        try {
+            c = Class.forName("java.nio.file.FileSystemException");
+        } catch (ClassNotFoundException x) {
+            throw new AssumptionViolatedException("prior to JDK 7", x);
+        }
+        File d = Util.createTempDir();
+        try {
+            File f = new File(d, "f");
+            OutputStream os = new FileOutputStream(f);
+            try {
+                Util.deleteFile(f);
+                fail("should not have been deletable");
+            } catch (IOException x) {
+                assertEquals(c, x.getClass());
+            } finally {
+                os.close();
+            }
+        } finally {
+            Util.deleteRecursive(d);
+        }
+    }
+
     @Test
     public void testHtmlEscape() {
         assertEquals("<br>", Util.escape("\n"));