CODEC-313: Add unit test

Signed-off-by: Arthur Chan <arthur.chan@adalogics.com>

Author: arthurscchan

src/test/java/org/apache/commons/codec/net/QuotedPrintableCodecTest.java

@@ -17,6 +17,7 @@
 
 package org.apache.commons.codec.net;
 
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
@@ -227,6 +228,15 @@ public void testSoftLineBreakEncode() throws Exception {
         assertEquals(qpdata, qpcodec.encode(decoded));
     }
 
+    @Test
+    public void testTooShortByteArray() {
+        assertDoesNotThrow(() -> {
+            final QuotedPrintableCodec qpcodec = new QuotedPrintableCodec(true);
+            final String qpdata = "AA";
+            assertNull(qpcodec.encode(qpdata), "Result should be null.");
+        });
+    }
+
     @Test
     public void testTrailingSpecial() throws Exception {
         final QuotedPrintableCodec qpcodec = new QuotedPrintableCodec(true);