Added regression tests based on originating test-gen tests

The relevant tests implemented in diffblue/test-gen/pull/479 (StringContains3 and StringContains4) for test-gen have been adapted and added as StringContains01 and StringContains02 resp. They have been marked as future in accordance to the standard for other tests. A contains smoke test already exists and is active, which was extended.

regression/strings-smoke-tests/java_contains/test.desc

@@ -1,8 +1,12 @@
 CORE
 test_contains.class
 --refine-strings
-^EXIT=0$
+^EXIT=10$
 ^SIGNAL=0$
 ^\[.*assertion.1\].* line 8.* SUCCESS$
+^\[.*assertion.2\].* line 9.* SUCCESS$
+^\[.*assertion.3\].* line 12.* FAILURE$
+^\[.*assertion.4\].* line 13.* FAILURE$
+^VERIFICATION FAILED$
 --
 Issue: diffblue/test-gen#201

regression/strings-smoke-tests/java_contains/test_contains.java

@@ -1,12 +1,15 @@
 public class test_contains
 {
-   public static void main(/*String[] argv*/)
+   public static void main(String x)
    {
       String s = new String("Abc");
       String u = "bc";
       String t = "ab";
       assert(s.contains(u));
-      // Long version:
-      // assert(s.contains(t));
+      assert(!s.contains(t));
+
+      String z = new String(x);
+      if (z.length() > 3) assert(t.contains(z));
+      else assert(z.contains(u));
    }
 }

regression/strings/StringContains01/test.desc

@@ -0,0 +1,6 @@
+FUTURE
+test.class
+--refine-strings
+^EXIT=10$
+^SIGNAL=0$
+^VERIFICATION FAILED$

regression/strings/StringContains01/test.java

@@ -0,0 +1,8 @@
+public class test
+{
+    public static void main(String s)
+    {
+        String ab = "abc";
+        assert(ab.contains(s));
+    }
+}

regression/strings/StringContains02/test.desc

@@ -0,0 +1,6 @@
+FUTURE
+test.class
+--refine-strings
+^EXIT=10$
+^SIGNAL=0$
+^VERIFICATION FAILED$

regression/strings/StringContains02/test.java

@@ -0,0 +1,7 @@
+public class test
+{
+    public static void main(String s)
+    {
+        assert(s.contains("Hello"));
+    }
+}