conditional format: fix failed match for range string

Strings used in a cell equality must be quoted. In order to
ensure this there is a check for non-range/non-numeric strings.
However this test wasn't anchored properly and gave a false
positive.

Issue #312

Author: jmcnamara

lib/Excel/Writer/XLSX/Worksheet.pm

@@ -10275,7 +10275,7 @@ sub _write_cf_rule {
             my $value = $param->{value};
 
             # String "Cell" values must be quoted, apart from ranges.
-            if (   $value !~ /(\$?)([A-Z]{1,3})(\$?)(\d+)/
+            if (   $value !~ /^(\$?)([A-Z]{1,3})(\$?)(\d+)/
                 && $value !~
                 /^([+-]?)(?=\d|\.\d)\d*(\.\d*)?([Ee]([+-]?\d+))?$/ )
             {

t/worksheet/worksheet_cond_format_25.t

@@ -0,0 +1,72 @@
+###############################################################################
+#
+# Tests for Excel::Writer::XLSX::Worksheet methods.
+#
+# Copyright 2000-2024, John McNamara, jmcnamara@cpan.org
+#
+# SPDX-License-Identifier: Artistic-1.0-Perl OR GPL-1.0-or-later
+#
+
+use lib 't/lib';
+use TestFunctions qw(_expected_to_aref _got_to_aref _is_deep_diff _new_worksheet);
+use strict;
+use warnings;
+
+use Test::More tests => 1;
+
+###############################################################################
+#
+# Tests setup.
+#
+my $expected;
+my $got;
+my $caption;
+my $worksheet;
+
+
+###############################################################################
+#
+# Test the _assemble_xml_file() method.
+#
+# Test conditional formats.
+#
+$caption = " \tWorksheet: _assemble_xml_file()";
+
+$worksheet = _new_worksheet(\$got);
+
+$worksheet->select();
+
+# Start test code.
+$worksheet->conditional_formatting( 'A1',
+    {
+        type     => 'cell',
+        format   => undef,
+        criteria => '==',
+        value    => 'Test A2',
+    }
+);
+# End test code.
+
+$worksheet->_assemble_xml_file();
+
+$expected = _expected_to_aref();
+$got      = _got_to_aref( $got );
+
+_is_deep_diff( $got, $expected, $caption );
+
+__DATA__
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<worksheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships">
+  <dimension ref="A1"/>
+  <sheetViews>
+    <sheetView tabSelected="1" workbookViewId="0"/>
+  </sheetViews>
+  <sheetFormatPr defaultRowHeight="15"/>
+  <sheetData/>
+  <conditionalFormatting sqref="A1">
+    <cfRule type="cellIs" priority="1" operator="equal">
+      <formula>"Test A2"</formula>
+    </cfRule>
+  </conditionalFormatting>
+  <pageMargins left="0.7" right="0.7" top="0.75" bottom="0.75" header="0.3" footer="0.3"/>
+</worksheet>