diff --git a/tests/cpp/CMakeLists.txt b/tests/cpp/CMakeLists.txt
index 59eda908..b29a9bd8 100644
--- a/tests/cpp/CMakeLists.txt
+++ b/tests/cpp/CMakeLists.txt
@@ -215,5 +215,16 @@ add_zkllvm_unit_test("algebra/de_composition/decomposition/lsb")
 #multi provers tests
 add_zkllvm_unit_test("multi_provers/shift_add")
 
+#customer's tests
+add_zkllvm_unit_test("custom_cases/getelementptr_as_constant/getelementptr_as_constant")
+
+#libc functions
+add_zkllvm_unit_test("libc/memset/memset")
+add_zkllvm_unit_test("libc/strlen/strlen")
+add_zkllvm_unit_test("libc/strcmp/strcmp")
+add_zkllvm_unit_test("libc/strncmp/strncmp")
+add_zkllvm_unit_test("libc/strcpy/strcpy")
+add_zkllvm_unit_test("libc/strncpy/strncpy")
+
 add_dependencies(all_for_test_run all_circuit_tests)
 add_dependencies(all_for_test_run all_expected_res_tests)
diff --git a/tests/cpp/custom_cases/getelementptr_as_constant/getelementptr_as_constant.cpp b/tests/cpp/custom_cases/getelementptr_as_constant/getelementptr_as_constant.cpp
new file mode 100644
index 00000000..0d29c0b9
--- /dev/null
+++ b/tests/cpp/custom_cases/getelementptr_as_constant/getelementptr_as_constant.cpp
@@ -0,0 +1,44 @@
+#ifndef __ZKLLVM__
+#include "../../read_boost_json.hpp"
+#include <cstdint>
+#include <fstream>
+#endif
+
+#include <nil/crypto3/algebra/curves/pallas.hpp>
+
+struct lumpinfo_s
+{
+    lumpinfo_s * next;
+    lumpinfo_s * prev;
+    int     data1;
+};
+
+lumpinfo_s first;
+
+[[circuit]] int list_demo(int unused) {
+
+    first.next = first.prev = &first;
+
+#ifndef __ZKLLVM__
+    std::cout << 0 <<std::endl;
+#endif
+
+    return 0;
+}
+
+#ifndef __ZKLLVM__
+
+int main (int argc, char *argv[]){
+    if (argc != 2) {
+        std::cerr << "one command line argument must be provided\n";
+        std::abort();
+    }
+
+    boost::json::value input_json = read_boost_json(std::string(argv[1]));
+
+    int a = read_uint<int>(input_json, 0);
+
+    list_demo(a);
+    return 0;
+}
+#endif
diff --git a/tests/cpp/libc/memset/memset.cpp b/tests/cpp/libc/memset/memset.cpp
new file mode 100644
index 00000000..13a17a25
--- /dev/null
+++ b/tests/cpp/libc/memset/memset.cpp
@@ -0,0 +1,41 @@
+#ifndef __ZKLLVM__
+#include "../../read_boost_json.hpp"
+#include <cstdint>
+#include <fstream>
+#endif
+
+#include <nil/crypto3/algebra/curves/pallas.hpp>
+
+[[circuit]] uint32_t test_func(char *buf) {
+    uint32_t out = 0;
+    memset((void*)buf, 5, 2);
+    out = buf[0] + buf[1];
+
+#ifndef __ZKLLVM__
+    std::cout << out <<std::endl;
+#endif
+
+    return out;
+}
+
+#ifndef __ZKLLVM__
+
+int main (int argc, char *argv[]){
+    if (argc != 2) {
+        std::cerr << "one command line argument must be provided\n";
+        std::abort();
+    }
+
+    boost::json::value input_json = read_boost_json(std::string(argv[1]));
+
+    std::string s = read_string(input_json, 0);
+
+    char* buf = new char[s.size()];
+    strcpy(buf, s.c_str());
+
+    test_func(buf);
+
+    delete[] buf;
+    return 0;
+}
+#endif
diff --git a/tests/cpp/libc/strcmp/strcmp.cpp b/tests/cpp/libc/strcmp/strcmp.cpp
new file mode 100644
index 00000000..85bc45bc
--- /dev/null
+++ b/tests/cpp/libc/strcmp/strcmp.cpp
@@ -0,0 +1,36 @@
+#ifndef __ZKLLVM__
+#include "../../read_boost_json.hpp"
+#include <cstdint>
+#include <fstream>
+#endif
+
+#include <nil/crypto3/algebra/curves/pallas.hpp>
+
+[[circuit]] int test_func(const char *s1, const char *s2) {
+    int out = strcmp(s1, s2);
+
+#ifndef __ZKLLVM__
+    std::cout << out <<std::endl;
+#endif
+
+    return out;
+}
+
+#ifndef __ZKLLVM__
+
+int main (int argc, char *argv[]){
+    if (argc != 2) {
+        std::cerr << "one command line argument must be provided\n";
+        std::abort();
+    }
+
+    boost::json::value input_json = read_boost_json(std::string(argv[1]));
+
+    std::string s1 = read_string(input_json, 0);
+    std::string s2 = read_string(input_json, 1);
+
+    test_func(s1.c_str(), s2.c_str());
+
+    return 0;
+}
+#endif
diff --git a/tests/cpp/libc/strcpy/strcpy.cpp b/tests/cpp/libc/strcpy/strcpy.cpp
new file mode 100644
index 00000000..46ce8d79
--- /dev/null
+++ b/tests/cpp/libc/strcpy/strcpy.cpp
@@ -0,0 +1,40 @@
+#ifndef __ZKLLVM__
+#include "../../read_boost_json.hpp"
+#include <cstdint>
+#include <fstream>
+#endif
+
+#include <nil/crypto3/algebra/curves/pallas.hpp>
+
+[[circuit]] uint32_t test_func(char *dst, const char *src) {
+    uint32_t out = 0;
+    char* ch = strcpy(dst, src);
+    out = ch[0] + ch[1];
+
+#ifndef __ZKLLVM__
+    std::cout << out <<std::endl;
+#endif
+
+    return out;
+}
+
+#ifndef __ZKLLVM__
+
+int main (int argc, char *argv[]){
+    if (argc != 2) {
+        std::cerr << "one command line argument must be provided\n";
+        std::abort();
+    }
+
+    boost::json::value input_json = read_boost_json(std::string(argv[1]));
+
+    std::string s = read_string(input_json, 0);
+
+    char* buf = new char[s.size()];
+
+    test_func(buf, s.c_str());
+
+    delete[] buf;
+    return 0;
+}
+#endif
diff --git a/tests/cpp/libc/strlen/strlen.cpp b/tests/cpp/libc/strlen/strlen.cpp
new file mode 100644
index 00000000..047f45c1
--- /dev/null
+++ b/tests/cpp/libc/strlen/strlen.cpp
@@ -0,0 +1,36 @@
+#ifndef __ZKLLVM__
+#include "../../read_boost_json.hpp"
+#include <cstdint>
+#include <fstream>
+#endif
+
+#include <nil/crypto3/algebra/curves/pallas.hpp>
+
+[[circuit]] uint32_t test_func(const char *buf) {
+    uint32_t out = 0;
+    out = strlen(buf);
+
+#ifndef __ZKLLVM__
+    std::cout << out <<std::endl;
+#endif
+
+    return out;
+}
+
+#ifndef __ZKLLVM__
+
+int main (int argc, char *argv[]){
+    if (argc != 2) {
+        std::cerr << "one command line argument must be provided\n";
+        std::abort();
+    }
+
+    boost::json::value input_json = read_boost_json(std::string(argv[1]));
+
+    std::string s = read_string(input_json, 0);
+
+    test_func(s.c_str());
+
+    return 0;
+}
+#endif
diff --git a/tests/cpp/libc/strncmp/strncmp.cpp b/tests/cpp/libc/strncmp/strncmp.cpp
new file mode 100644
index 00000000..0a65912c
--- /dev/null
+++ b/tests/cpp/libc/strncmp/strncmp.cpp
@@ -0,0 +1,38 @@
+#ifndef __ZKLLVM__
+#include "../../read_boost_json.hpp"
+#include <cstdint>
+#include <fstream>
+#endif
+
+#include <nil/crypto3/algebra/curves/pallas.hpp>
+
+[[circuit]] int test_func(const char *s1, const char *s2, uint32_t n) {
+    int out = strncmp(s1, s2, n);
+
+#ifndef __ZKLLVM__
+    std::cout << out <<std::endl;
+#endif
+
+    return out;
+}
+
+#ifndef __ZKLLVM__
+
+int main (int argc, char *argv[]){
+    if (argc != 2) {
+        std::cerr << "one command line argument must be provided\n";
+        std::abort();
+    }
+
+    boost::json::value input_json = read_boost_json(std::string(argv[1]));
+
+    std::string s1 = read_string(input_json, 0);
+    std::string s2 = read_string(input_json, 1);
+    uint32_t n = read_uint<uint32_t>(input_json, 2);
+
+
+    test_func(s1.c_str(), s2.c_str(), n);
+
+    return 0;
+}
+#endif
diff --git a/tests/cpp/libc/strncpy/strncpy.cpp b/tests/cpp/libc/strncpy/strncpy.cpp
new file mode 100644
index 00000000..af857bd3
--- /dev/null
+++ b/tests/cpp/libc/strncpy/strncpy.cpp
@@ -0,0 +1,42 @@
+#ifndef __ZKLLVM__
+#include "../../read_boost_json.hpp"
+#include <cstdint>
+#include <fstream>
+#endif
+
+#include <nil/crypto3/algebra/curves/pallas.hpp>
+
+[[circuit]] uint32_t test_func(char *dst, const char *src, uint32_t n) {
+    uint32_t out = 0;
+    char* ch = strncpy(dst, src, n);
+    out = ch[0] + ch[1];
+
+#ifndef __ZKLLVM__
+    std::cout << out <<std::endl;
+#endif
+
+    return out;
+}
+
+#ifndef __ZKLLVM__
+
+int main (int argc, char *argv[]){
+    if (argc != 2) {
+        std::cerr << "one command line argument must be provided\n";
+        std::abort();
+    }
+
+    boost::json::value input_json = read_boost_json(std::string(argv[1]));
+
+    std::string s = read_string(input_json, 0);
+    uint32_t n = read_uint<uint32_t>(input_json, 2);
+
+    char* buf = new char[s.size()];
+    memset((void*)buf, 0, s.size());
+
+    test_func(buf, s.c_str(), n);
+
+    delete[] buf;
+    return 0;
+}
+#endif
\ No newline at end of file
diff --git a/tests/cpp/read_boost_json.hpp b/tests/cpp/read_boost_json.hpp
index bcfdbdd1..f8218e4d 100644
--- a/tests/cpp/read_boost_json.hpp
+++ b/tests/cpp/read_boost_json.hpp
@@ -168,4 +168,16 @@ PointType read_curve(boost::json::value& input_json_value, std::size_t position)
         }
     }
     return res;
+}
+
+std::string read_string(boost::json::value& input_json_value, std::size_t position) {
+
+    const boost::json::object &current_value = input_json_value.as_array()[position].as_object();
+    if(!current_value.contains("string"))
+        assert(false && "json value must contain \"string\"");
+    if (current_value.at("string").is_string()) {
+        assert(false && "value is not string.");
+    }
+
+    return current_value.at("string").as_string().c_str();
 }
\ No newline at end of file
diff --git a/tests/disabled_inputs/libc/strcmp/0_1.inp b/tests/disabled_inputs/libc/strcmp/0_1.inp
new file mode 100644
index 00000000..db520815
--- /dev/null
+++ b/tests/disabled_inputs/libc/strcmp/0_1.inp
@@ -0,0 +1 @@
+[ {"string": "abc"}, {"string": "abx"}]
diff --git a/tests/disabled_inputs/libc/strncmp/0_1.inp b/tests/disabled_inputs/libc/strncmp/0_1.inp
new file mode 100644
index 00000000..6f24fbf1
--- /dev/null
+++ b/tests/disabled_inputs/libc/strncmp/0_1.inp
@@ -0,0 +1 @@
+[ {"string": "abc"}, {"string": "abx"}, {"int": 3}]
diff --git a/tests/inputs/custom_cases/getelementptr_as_constant/0_0.inp b/tests/inputs/custom_cases/getelementptr_as_constant/0_0.inp
new file mode 100644
index 00000000..44d0c735
--- /dev/null
+++ b/tests/inputs/custom_cases/getelementptr_as_constant/0_0.inp
@@ -0,0 +1 @@
+[ {"int": 10}]
diff --git a/tests/inputs/libc/memset/0_0.inp b/tests/inputs/libc/memset/0_0.inp
new file mode 100644
index 00000000..c5a9f68a
--- /dev/null
+++ b/tests/inputs/libc/memset/0_0.inp
@@ -0,0 +1 @@
+[ {"string": "ab"}]
diff --git a/tests/inputs/libc/strcmp/0_0.inp b/tests/inputs/libc/strcmp/0_0.inp
new file mode 100644
index 00000000..f1a6ffc3
--- /dev/null
+++ b/tests/inputs/libc/strcmp/0_0.inp
@@ -0,0 +1 @@
+[ {"string": "abc"}, {"string": "abc"}]
diff --git a/tests/inputs/libc/strcmp/0_2.inp b/tests/inputs/libc/strcmp/0_2.inp
new file mode 100644
index 00000000..cd69c7ab
--- /dev/null
+++ b/tests/inputs/libc/strcmp/0_2.inp
@@ -0,0 +1 @@
+[ {"string": "abx"}, {"string": "abc"}]
diff --git a/tests/inputs/libc/strcmp/0_3.inp b/tests/inputs/libc/strcmp/0_3.inp
new file mode 100644
index 00000000..68c02a45
--- /dev/null
+++ b/tests/inputs/libc/strcmp/0_3.inp
@@ -0,0 +1 @@
+[ {"string": "abc"}, {"string": "ab"}]
diff --git a/tests/inputs/libc/strcpy/0_0.inp b/tests/inputs/libc/strcpy/0_0.inp
new file mode 100644
index 00000000..f1a6ffc3
--- /dev/null
+++ b/tests/inputs/libc/strcpy/0_0.inp
@@ -0,0 +1 @@
+[ {"string": "abc"}, {"string": "abc"}]
diff --git a/tests/inputs/libc/strlen/0_0.inp b/tests/inputs/libc/strlen/0_0.inp
new file mode 100644
index 00000000..56c46eb4
--- /dev/null
+++ b/tests/inputs/libc/strlen/0_0.inp
@@ -0,0 +1 @@
+[ {"string": "abc"}]
diff --git a/tests/inputs/libc/strncmp/0_0.inp b/tests/inputs/libc/strncmp/0_0.inp
new file mode 100644
index 00000000..187c41af
--- /dev/null
+++ b/tests/inputs/libc/strncmp/0_0.inp
@@ -0,0 +1 @@
+[ {"string": "abc"}, {"string": "abc"}, {"int": 3}]
diff --git a/tests/inputs/libc/strncmp/0_2.inp b/tests/inputs/libc/strncmp/0_2.inp
new file mode 100644
index 00000000..fac3f9a8
--- /dev/null
+++ b/tests/inputs/libc/strncmp/0_2.inp
@@ -0,0 +1 @@
+[ {"string": "abx"}, {"string": "abc"}, {"int": 3}]
diff --git a/tests/inputs/libc/strncmp/0_3.inp b/tests/inputs/libc/strncmp/0_3.inp
new file mode 100644
index 00000000..6316bfaf
--- /dev/null
+++ b/tests/inputs/libc/strncmp/0_3.inp
@@ -0,0 +1 @@
+[ {"string": "abc"}, {"string": "abx"}, {"int": 2}]
diff --git a/tests/inputs/libc/strncpy/0_0.inp b/tests/inputs/libc/strncpy/0_0.inp
new file mode 100644
index 00000000..f561b649
--- /dev/null
+++ b/tests/inputs/libc/strncpy/0_0.inp
@@ -0,0 +1 @@
+[ {"string": "ab"}, {"string": "ab"}, {"int": 3}]
diff --git a/tests/inputs/libc/strncpy/0_1.inp b/tests/inputs/libc/strncpy/0_1.inp
new file mode 100644
index 00000000..a50c80d4
--- /dev/null
+++ b/tests/inputs/libc/strncpy/0_1.inp
@@ -0,0 +1 @@
+[ {"string": "abc"}, {"string": "abc"}, {"int": 2}]