Uncomment and update null tests for FileUtils.toURLs(File...) (#546)

* uncomment and update null tests for toURLs

* javadoc

Author: elharo

src/main/java/org/apache/commons/io/FileUtils.java

@@ -3054,15 +3054,15 @@ public static void touch(final File file) throws IOException {
     }
 
     /**
-     * Converts each of an array of {@link File} to a {@link URL}.
+     * Converts each element of an array of {@link File} to a {@link URL}.
      * <p>
      * Returns an array of the same size as the input.
      * </p>
      *
      * @param files the files to convert, must not be {@code null}
      * @return an array of URLs matching the input
      * @throws IOException          if a file cannot be converted
-     * @throws NullPointerException if the parameter is null
+     * @throws NullPointerException if any argument is null
      */
     public static URL[] toURLs(final File... files) throws IOException {
         Objects.requireNonNull(files, "files");

src/test/java/org/apache/commons/io/FileUtilsTest.java

@@ -791,25 +791,22 @@ public void testCopyDirectoryFiltered() throws IOException {
         assertEquals("file3.txt", files.get(2).getName());
     }
 
-//   @Test public void testToURLs2() throws Exception {
-//        File[] files = new File[] {
-//            new File(temporaryFolder, "file1.txt"),
-//            null,
-//        };
-//        URL[] urls = FileUtils.toURLs(files);
-//
-//        assertEquals(files.length, urls.length);
-//        assertTrue(urls[0].toExternalForm().startsWith("file:"));
-//        assertTrue(urls[0].toExternalForm().indexOf("file1.txt") > 0);
-//        assertEquals(null, urls[1]);
-//    }
-//
-//   @Test public void testToURLs3() throws Exception {
-//        File[] files = null;
-//        URL[] urls = FileUtils.toURLs(files);
-//
-//        assertEquals(0, urls.length);
-//    }
+    @Test
+    public void testToURLs2() {
+        final File[] files = new File[] {
+            new File(tempDirFile, "file1.txt"),
+            null,
+        };
+        assertThrows(NullPointerException.class, () -> FileUtils.toURLs(files),
+                "Can't convert null URL");
+    }
+
+    @Test
+    public void testToURLs3() {
+        final File[] files = null;
+        assertThrows(NullPointerException.class, () -> FileUtils.toURLs(files),
+                "Can't convert null list");
+    }
 
     @Test
     public void testCopyDirectoryPreserveDates() throws Exception {