Add tests of FileUtil and NoPathParameterException

Also, remove unused method.

Author: idodeclare

opengrok-web/src/main/java/org/opengrok/web/util/NoPathParameterException.java

@@ -19,17 +19,14 @@
 
 /*
  * Copyright (c) 2020 Oracle and/or its affiliates. All rights reserved.
+ * Portions Copyright (c) 2020, Chris Fraire <[email protected]>.
  */
 
 package org.opengrok.web.util;
 
 public class NoPathParameterException extends Exception {
     private static final long serialVersionUID = 1L;
 
-    public NoPathParameterException() {
-        super();
-    }
-
     public NoPathParameterException(String message) {
         super(message);
     }

opengrok-web/src/test/java/org/opengrok/web/util/FileUtilTest.java

@@ -0,0 +1,48 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * See LICENSE.txt included in this distribution for the specific
+ * language governing permissions and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at LICENSE.txt.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright (c) 2020, Chris Fraire <[email protected]>.
+ */
+
+package org.opengrok.web.util;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.Test;
+import java.io.FileNotFoundException;
+import java.util.UUID;
+
+/**
+ * Represents a container for tests of {@link FileUtil}.
+ */
+public class FileUtilTest {
+
+    @Test
+    public void shouldThrowOnNullArgument() throws FileNotFoundException {
+        assertThrows(NoPathParameterException.class, () -> FileUtil.toFile(null),
+                "toFile(null)");
+    }
+
+    @Test
+    public void shouldThrowOnMissingFile() throws NoPathParameterException {
+        assertThrows(FileNotFoundException.class, () -> FileUtil.toFile(
+                UUID.randomUUID().toString()), "toFile(randomUUID)");
+    }
+}