Add failing test for HtmlConverter.linkifyText()

There's currently a bug in linkifyText() that can lead to a
StringIndexOutOfBoundsException when the text contains a
bitcoin URI and a "web" URI near the end of the text.

src/com/fsck/k9/helper/HtmlConverter.java

@@ -391,7 +391,7 @@ public class HtmlConverter {
      * @param text Plain text to be linkified.
      * @param outputBuffer Buffer to append linked text to.
      */
-    private static void linkifyText(final String text, final StringBuffer outputBuffer) {
+    protected static void linkifyText(final String text, final StringBuffer outputBuffer) {
         String prepared = text.replaceAll(Regex.BITCOIN_URI_PATTERN, "<a href=\"$0\">$0</a>");
 
         Matcher m = Regex.WEB_URL_PATTERN.matcher(prepared);

tests/src/com/fsck/k9/helper/HtmlConverterTest.java

@@ -167,4 +167,18 @@ public class HtmlConverterTest extends TestCase {
                 + "</blockquote>"
                 + "</pre>", result);
     }
+
+    public void testLinkifyBitcoinAndHttpUri() {
+        String text = "bitcoin:19W6QZkx8SYPG7BBCS7odmWGRxqRph5jFU http://example.com/";
+
+        StringBuffer outputBuffer = new StringBuffer();
+        HtmlConverter.linkifyText(text, outputBuffer);
+
+        assertEquals("<a href=\"bitcoin:19W6QZkx8SYPG7BBCS7odmWGRxqRph5jFU\">" +
+                "bitcoin:19W6QZkx8SYPG7BBCS7odmWGRxqRph5jFU" +
+                "</a> " +
+                "<a href=\"http://example.com/\">" +
+                "http://example.com/" +
+                "</a>", outputBuffer.toString());
+    }
 }