[test-owner-report] properly test link amounts

Previous test wasn't comprehensive; due to variable row lengths,
the (td 11) wouldn't consistently select the link amount. using
(td -1) will select the last <td> element in the row.

Moreover also test the class-name to target the link amounts otherwise
other elements (eg the aging-list) will also be returned.

gnucash/report/business-reports/test/test-owner-report.scm

@@ -327,6 +327,7 @@
          sxml)))
     (test-end "customer-report")
 
+    (display "new-owner-report tests:\n")
     (test-begin "new-customer-report")
     (let* ((options (default-testing-options 'customer-new
                       owner-1 (get-acct "AR-USD")))
@@ -351,9 +352,18 @@
           "$228.00" "$28.00" "$34.75" "$31.75")
         ((sxpath `(// (table 3) // tr (td 8) // *text*))
          sxml))
-      (test-equal "link-amounts"
-        '("$1.50" "$11.50" "$11.50" "$200.00" "$200.00")
-        ((sxpath `(// (table 3) // tr (td 11) // *text*))
+      (test-equal "positive-link-amounts"
+        '("$1.50" "$2.00" "$8.00" "$7.50" "$8.50" "$11.50" "$11.50"
+          "$4.00" "$200.00" "$200.00" "$6.75")
+        ((sxpath `(// (table 3) // tr
+                      (td -1 (@ (equal? (class "number-cell")))) //
+                      *text*))
+         sxml))
+      (test-equal "negative-link-amounts"
+        '("-$3.00")
+        ((sxpath `(// (table 3) // tr
+                      (td -1 (@ (equal? (class "number-cell neg")))) //
+                      *text*))
          sxml))
       ;; from the report, find the 3rd table, last row, find embedded
       ;; table, retrieve tr contents