Regression: StringBuilder append with int argument

This specifies a substring to append and was not tested before.

Author: romainbrenguier

regression/strings-smoke-tests/java_append_string/test_append_string.class

@@ -1,14 +1,29 @@
 public class test_append_string
 {
-   public static void main(/*String[] args*/)
-   {
-      String di = new String("di");
-      StringBuilder diff = new StringBuilder();
-      diff.append(di);
-      diff.append("ff");
-      System.out.println(diff);
-      String s = diff.toString();
-      System.out.println(s);
-      assert s.equals("diff");
-   }
+    public static void main()
+    {
+        String di = new String("di");
+        StringBuilder diff = new StringBuilder();
+        diff.append(di);
+        diff.append("ff");
+        System.out.println(diff);
+        String s = diff.toString();
+        System.out.println(s);
+        assert s.equals("diff");
+    }
+
+    public static void check(StringBuilder sb, String str)
+    {
+        String init = sb.toString();
+        if(str.length() >= 4)
+        {
+            sb.append(str, 2, 4);
+            String res = sb.toString();
+            assert(res.startsWith(init));
+            assert(res.endsWith(str.substring(2, 4)));
+            assert(res.length() == init.length() + 2);
+            assert(!res.equals("foobarfuz"));
+        }
+    }
+
 }

regression/strings-smoke-tests/java_append_string/test_append_string.java

@@ -0,0 +1,10 @@
+CORE
+test_append_string.class
+--refine-strings --string-max-length 10 --function test_append_string.check --java-assume-inputs-non-null
+^EXIT=10$
+^SIGNAL=0$
+^\[.*assertion.*\].* line 22.* SUCCESS$
+^\[.*assertion.*\].* line 23.* SUCCESS$
+^\[.*assertion.*\].* line 24.* SUCCESS$
+^\[.*assertion.*\].* line 25.* FAILURE$
+--