Add test for stubbed string constructor

Author: Antonia Lechner

jbmc/regression/jbmc-strings/stubbed-constructor/Test.class

@@ -0,0 +1,11 @@
+import java.lang.String;
+
+public class Test {
+
+  public static void test() {
+    char[] c1 = new char[] { 'j', 'a', 'v', 'a' };
+    String s = new String (c1);
+    assert s.charAt(0) == 'j';
+  }
+
+}

jbmc/regression/jbmc-strings/stubbed-constructor/Test.java

@@ -0,0 +1,12 @@
+CORE
+Test.class
+--function Test.test --show-properties
+^EXIT=0$
+^SIGNAL=0$
+--
+--
+This test checks that for a stubbed String constructor in the method to verify
+(such a constructor will be stubbed if no model for String is loaded), we still
+generate properties for this method.
+Note that verification would fail in this case because we don't know the correct
+implementation of the constructor.