2 files changed, 94 insertions, 1 deletions
diff --git a/test/unit/theory/CMakeLists.txt b/test/unit/theory/CMakeLists.txt
index a5a67cfa2..3d29c4de1 100644
--- a/test/unit/theory/CMakeLists.txt
+++ b/test/unit/theory/CMakeLists.txt
@@ -1,11 +1,12 @@
+cvc4_add_unit_test_black(theory_black theory)
 cvc4_add_unit_test_white(evaluator_white theory)
 cvc4_add_unit_test_white(logic_info_white theory)
 cvc4_add_unit_test_white(theory_arith_white theory)
-cvc4_add_unit_test_black(theory_black theory)
 cvc4_add_unit_test_white(theory_bv_white theory)
 cvc4_add_unit_test_white(theory_engine_white theory)
 cvc4_add_unit_test_white(theory_quantifiers_bv_instantiator_white theory)
 cvc4_add_unit_test_white(theory_quantifiers_bv_inverter_white theory)
 cvc4_add_unit_test_white(theory_strings_rewriter_white theory)
+cvc4_add_unit_test_white(theory_strings_skolem_cache_black theory)
 cvc4_add_unit_test_white(theory_white theory)
 cvc4_add_unit_test_white(type_enumerator_white theory)
diff --git a/test/unit/theory/theory_strings_skolem_cache_black.h b/test/unit/theory/theory_strings_skolem_cache_black.h
new file mode 100644
index 000000000..aaf50f219
--- /dev/null
+++ b/test/unit/theory/theory_strings_skolem_cache_black.h
@@ -0,0 +1,92 @@
+/*********************                                                        */
+/*! \file theory_strings_skolem_cache_black.h
+ ** \verbatim
+ ** Top contributors (to current version):
+ **   Andres Noetzli
+ ** This file is part of the CVC4 project.
+ ** Copyright (c) 2009-2018 by the authors listed in the file AUTHORS
+ ** in the top-level source directory) and their institutional affiliations.
+ ** All rights reserved.  See the file COPYING in the top-level source
+ ** directory for licensing information.\endverbatim
+ **
+ ** \brief Black box testing of the skolem cache of the theory of strings.
+ **/
+
+#include <cxxtest/TestSuite.h>
+
+#include <memory>
+
+#include "expr/node.h"
+#include "expr/node_manager.h"
+#include "theory/strings/skolem_cache.h"
+#include "util/rational.h"
+#include "util/regexp.h"
+
+using namespace CVC4;
+using namespace CVC4::theory::strings;
+
+class TheoryStringsSkolemCacheBlack : public CxxTest::TestSuite
+{
+ public:
+  void setUp() override
+  {
+    d_nm.reset(new NodeManager(nullptr));
+    d_scope.reset(new NodeManagerScope(d_nm.get()));
+  }
+
+  void tearDown() override {}
+
+  void testMkSkolemCached()
+  {
+    Node zero = d_nm->mkConst(Rational(0));
+    Node n = d_nm->mkSkolem("n", d_nm->integerType());
+    Node a = d_nm->mkSkolem("a", d_nm->stringType());
+    Node b = d_nm->mkSkolem("b", d_nm->stringType());
+    Node c = d_nm->mkSkolem("c", d_nm->stringType());
+    Node d = d_nm->mkSkolem("d", d_nm->stringType());
+    Node sa = d_nm->mkNode(kind::STRING_SUBSTR,
+                           a,
+                           zero,
+                           d_nm->mkNode(kind::STRING_STRIDOF, a, b, zero));
+    Node sc = d_nm->mkNode(kind::STRING_SUBSTR, c, zero, n);
+
+    SkolemCache sk;
+
+    // Check that skolems are shared between:
+    //
+    // SK_FIRST_CTN(a, b)
+    //
+    // SK_FIRST_CTN(a, b)
+    {
+      Node s1 = sk.mkSkolemCached(a, b, SkolemCache::SK_FIRST_CTN_PRE, "foo");
+      Node s2 = sk.mkSkolemCached(a, b, SkolemCache::SK_FIRST_CTN_PRE, "foo");
+      TS_ASSERT_EQUALS(s1, s2);
+    }
+
+    // Check that skolems are shared between:
+    //
+    // SK_FIRST_CTN(c, b)
+    //
+    // SK_FIRST_CTN((str.substr c), b)
+    {
+      Node s1 = sk.mkSkolemCached(c, b, SkolemCache::SK_FIRST_CTN_PRE, "foo");
+      Node s2 = sk.mkSkolemCached(sc, b, SkolemCache::SK_FIRST_CTN_PRE, "foo");
+      TS_ASSERT_EQUALS(s1, s2);
+    }
+
+    // Check that skolems are shared between:
+    //
+    // SK_PURIFY((str.substr a 0 (str.indexof a b 0)))
+    //
+    // SK_FIRST_CTN(a, b)
+    {
+      Node s1 = sk.mkSkolemCached(sa, b, SkolemCache::SK_PURIFY, "foo");
+      Node s2 = sk.mkSkolemCached(a, b, SkolemCache::SK_FIRST_CTN_PRE, "foo");
+      TS_ASSERT_EQUALS(s1, s2);
+    }
+  }
+
+ private:
+  std::unique_ptr<NodeManager> d_nm;
+  std::unique_ptr<NodeManagerScope> d_scope;
+};