[bugfix] Fix double negative character issue in negative exponents when using fn:format-number

Closes eXist-db/exist#5943

Author: adamretter

exist-core/pom.xml

@@ -791,6 +791,7 @@
                                 <include>src/test/resources/standalone-webapp/WEB-INF/web.xml</include>
                                 <include>src/test/xquery/tail-recursion.xml</include>
                                 <include>src/test/xquery/maps/maps.xqm</include>
+                                <include>src/test/xquery/numbers/format-numbers.xql</include>
                                 <include>src/test/xquery/util/util.xml</include>
                                 <include>src/test/xquery/xquery3/parse-xml.xqm</include>
                                 <include>src/test/xquery/xquery3/serialize.xql</include>
@@ -1374,6 +1375,7 @@
                                 <exclude>src/test/xquery/tail-recursion.xml</exclude>
                                 <exclude>src/test/xquery/type-promotion.xqm</exclude>
                                 <exclude>src/test/xquery/maps/maps.xqm</exclude>
+                                <exclude>src/test/xquery/numbers/format-numbers.xql</exclude>
                                 <exclude>src/test/xquery/securitymanager/acl.xqm</exclude>
                                 <exclude>src/test/xquery/util/util.xml</exclude>
                                 <exclude>src/test/xquery/xqsuite/xqsuite-assertions-dynamic.xqm</exclude>

exist-core/src/main/java/org/exist/xquery/functions/fn/FnFormatNumbers.java

@@ -713,9 +713,6 @@ private String format(final NumericValue number, final DecimalFormat decimalForm
         final int minimumExponentSize = subPicture.getMinimumExponentSize();
         if (minimumExponentSize > 0) {
             formatted.append(decimalFormat.exponentSeparator);
-            if (exp < 0) {
-                formatted.append(decimalFormat.minusSign);
-            }
 
             final CodePointString expStr = new CodePointString(String.valueOf(exp));
 

exist-core/src/test/xquery/numbers/format-numbers.xql

@@ -1,4 +1,28 @@
 (:
+ : Elemental
+ : Copyright (C) 2024, Evolved Binary Ltd
+ :
+ : [email protected]
+ : https://www.evolvedbinary.com | https://www.elemental.xyz
+ :
+ : This library is free software; you can redistribute it and/or
+ : modify it under the terms of the GNU Lesser General Public
+ : License as published by the Free Software Foundation; version 2.1.
+ :
+ : This library is distributed in the hope that it will be useful,
+ : but WITHOUT ANY WARRANTY; without even the implied warranty of
+ : MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ : Lesser General Public License for more details.
+ :
+ : You should have received a copy of the GNU Lesser General Public
+ : License along with this library; if not, write to the Free Software
+ : Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ :
+ : NOTE: Parts of this file contain code from 'The eXist-db Authors'.
+ :       The original license header is included below.
+ :
+ : =====================================================================
+ :
  : eXist-db Open Source Native XML Database
  : Copyright (C) 2001 The eXist-db Authors
  :
@@ -303,4 +327,17 @@ declare
     %test:assertEquals("0.0")
 function fd:decimal-zeros($picture as xs:string) {
     format-number(0, $picture)
+};
+
+declare
+    %test:args("1.234567E10")
+    %test:assertEquals("1.235e10")
+    %test:args("1.234567E-10")
+    %test:assertEquals("1.235e-10")
+    %test:args("0.00000000123456")
+    %test:assertEquals("1.235e-9")
+    %test:args("1.234567e-10")
+    %test:assertEquals("1.235e-10")
+function fd:negative-exponent($value as xs:numeric) {
+    format-number($value, "0.000e0")
 };