IO-665 ensure that passing a null InputStream results in NPE with tests (#112)

* ensure that passing a null InputStream results in NPE with tests

* remove stray import from bad autocomplete

* per review, fix formating for lamda () ->

* per review, protect other constructors

Author: ottobackwards

src/main/java/org/apache/commons/io/input/XmlStreamReader.java

@@ -30,6 +30,7 @@
 import java.net.URLConnection;
 import java.text.MessageFormat;
 import java.util.Locale;
+import java.util.Objects;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -135,7 +136,7 @@ public String getDefaultEncoding() {
      * @throws IOException thrown if there is a problem reading the file.
      */
     public XmlStreamReader(final File file) throws IOException {
-        this(new FileInputStream(file));
+        this(new FileInputStream(Objects.requireNonNull(file)));
     }
 
     /**
@@ -214,6 +215,7 @@ public XmlStreamReader(final InputStream inputStream, final boolean lenient) thr
      */
     public XmlStreamReader(final InputStream inputStream, final boolean lenient, final String defaultEncoding)
             throws IOException {
+        Objects.requireNonNull(inputStream, "inputStream");
         this.defaultEncoding = defaultEncoding;
         final BOMInputStream bom = new BOMInputStream(new BufferedInputStream(inputStream, BUFFER_SIZE), false, BOMS);
         final BOMInputStream pis = new BOMInputStream(bom, true, XML_GUESS_BYTES);
@@ -239,7 +241,7 @@ public XmlStreamReader(final InputStream inputStream, final boolean lenient, fin
      *         the URL.
      */
     public XmlStreamReader(final URL url) throws IOException {
-        this(url.openConnection(), null);
+        this(Objects.requireNonNull(url, "url").openConnection(), null);
     }
 
     /**
@@ -262,6 +264,7 @@ public XmlStreamReader(final URL url) throws IOException {
      *         the URLConnection.
      */
     public XmlStreamReader(final URLConnection conn, final String defaultEncoding) throws IOException {
+        Objects.requireNonNull(conn, "conm");
         this.defaultEncoding = defaultEncoding;
         final boolean lenient = true;
         final String contentType = conn.getContentType();
@@ -334,6 +337,7 @@ public XmlStreamReader(final InputStream inputStream, final String httpContentTy
      */
     public XmlStreamReader(final InputStream inputStream, final String httpContentType,
             final boolean lenient, final String defaultEncoding) throws IOException {
+        Objects.requireNonNull(inputStream, "inputStream");
         this.defaultEncoding = defaultEncoding;
         final BOMInputStream bom = new BOMInputStream(new BufferedInputStream(inputStream, BUFFER_SIZE), false, BOMS);
         final BOMInputStream pis = new BOMInputStream(bom, true, XML_GUESS_BYTES);

src/test/java/org/apache/commons/io/input/XmlStreamReaderTest.java

@@ -17,15 +17,19 @@
 package org.apache.commons.io.input;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
+import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStreamWriter;
 import java.io.Writer;
+import java.net.URL;
+import java.net.URLConnection;
 import java.text.MessageFormat;
 import java.util.HashMap;
 import java.util.Map;
@@ -78,6 +82,26 @@ protected void _testRawNoBomInvalid(final String encoding) throws Exception {
         }
     }
 
+    @Test
+    protected void testNullFileInput() throws IOException {
+        assertThrows(NullPointerException.class, () -> new XmlStreamReader((File)null));
+    }
+
+    @Test
+    protected void testNullInputStreamInput() throws IOException {
+        assertThrows(NullPointerException.class, () -> new XmlStreamReader((InputStream) null));
+    }
+
+    @Test
+    protected void testNullURLInput() throws IOException {
+         assertThrows(NullPointerException.class, () -> new XmlStreamReader((URL)null));
+    }
+
+    @Test
+    protected void testNullURLConnectionInput() throws IOException {
+          assertThrows(NullPointerException.class, () -> new XmlStreamReader((URLConnection)null, "US-ASCII"));
+    }
+
     @Test
     public void testRawNoBomUsAscii() throws Exception {
         _testRawNoBomValid("US-ASCII");