diff --git a/src/specmicp_common/filesystem.cpp b/src/specmicp_common/filesystem.cpp
index 713c47d..20c379c 100644
--- a/src/specmicp_common/filesystem.cpp
+++ b/src/specmicp_common/filesystem.cpp
@@ -1,213 +1,228 @@
 /* =============================================================================
 
  Copyright (c) 2014 - 2016
  F. Georget <fabieng@princeton.edu> Princeton University
  All rights reserved.
 
 
 Redistribution and use in source and binary forms, with or without modification,
 are permitted provided that the following conditions are met:
 
     1. Redistributions of source code must retain the above copyright notice,
     this list of conditions and the following disclaimer.
 
     2. Redistributions in binary form must reproduce the above copyright notice,
     this list of conditions and the following disclaimer in the documentation
     and/or other materials provided with the distribution.
 
     3. Neither the name of the copyright holder nor the names of its
     contributors may be used to endorse or promote products derived from this
     software without specific prior written permission.
 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. *
 
 ============================================================================= */
 
 #include "filesystem.hpp"
 
 #include <string.h>
 #include <dirent.h>
 #include <unistd.h>
 #include <sys/stat.h>
 #include <stdexcept>
 #include <limits.h>
 #include <stdlib.h>
 
 #include "specmicp_common/config.h"
 
 #include "log.hpp"
 
 static std::string test_name;
 
 namespace specmicp {
 namespace utils {
 
 bool is_directory(const std::string& path)
 {
     struct stat info;
     if (stat(path.c_str(), &info) == -1) {
         return false;
     }
     if (S_ISDIR(info.st_mode)) {
         return true;
     }
     return false;
 }
 
 
 bool is_file(const std::string& path)
 {
     struct stat info;
     if (stat(path.c_str(), &info) == -1) {
         return false;
     }
     if (S_ISREG(info.st_mode)) {
         return true;
     }
     return false;
 }
 
 std::string get_current_directory()
 {
     char buf[PATH_MAX];
     char* test = getcwd(buf, PATH_MAX);
     if (test == NULL) {
         ERROR << "Unable to obtain current working directory";
         throw std::runtime_error("Something is wrong,"
              "unable to obtain the current directory.");
     }
     return std::string(buf);
 }
 
 std::string complete_path(
         const std::string& dir,
         const std::string& file
         )
 {
     std::string complete = dir;
     if (dir.back() != '/') {
         complete += '/';
     }
     complete += file;
     return complete;
 }
 
 
 std::string relative_to_absolute(
         const std::string& rel_path,
         std::string& error
         )
 {
     std::string abs_path = "";
     char buf[PATH_MAX];
     // call posix function
     char* res = realpath(rel_path.c_str(), buf);
     if (res == NULL) {
         // parse error
         if (errno == ENOENT) {
             error = "No such file '" + rel_path +"'.";
         } else if (errno == EACCES) {
             error = "Read permission denied while searching for '"
                     + rel_path +"'.";
         } else if (errno == EIO) {
             error = "I/O error while searching for '"
                     + rel_path +"'.";
         } else {
             error = "Error while accessing '" + rel_path + "'.";
         }
     } else {
         // no error, copy buffer
         abs_path = buf;
     }
     return abs_path;
 }
 
 int name_filter(const struct dirent64* entry)
 {
     auto res = strncmp(entry->d_name, test_name.c_str(), 256);
     if (res == 0) {
         return 1;
     }
     return 0;
 }
 
 std::string find_path(
         std::string filename,
         const std::vector<std::string> &directories
         )
 {
     // check if filename is a path
     const auto has_sep = filename.find('/');
     if (has_sep != std::string::npos) {
         // already a path => we convert it to absolute
         std::string error = "";
         auto filepath = relative_to_absolute(filename, error);
         if (filepath == "") {
             ERROR << error;
             return ""; // empty string is signal for error
         }
         return filepath;
     }
 
     // if not a path we try to find it
     std::string complete_path_str = "";
     test_name = filename.c_str();
     for (auto dir: directories)
     {
         bool found = false;
         struct dirent64** entry_list;
         auto count = scandir64(dir.c_str(), &entry_list, name_filter, alphasort64);
         if (count < 0) {
             ERROR << "Problem while scanning directory : " << dir << ".";
             throw std::runtime_error("Problem while scanning directory "
                                      + dir + ".");
         }
         if (count == 0) {
             continue;
         }
 
         if (count > 1) {
             WARNING << "More that one match for file '" << filename
                     << "in : " << dir << ".";
         }
 
         for (auto ind=0; ind<count; ++ind) {
             struct dirent64* entry;
             entry = entry_list[0];
             if (not found) {
                 complete_path_str = complete_path(dir, entry->d_name);
             }
             free(entry); // need to free everything
         }
         free(entry_list);
         if (found) break;
     }
     return complete_path_str;
 }
 
 
+bool has_env(
+        const std::string& env_var
+        )
+{
+#ifdef SPECMICP_HAVE_SECURE_GETENV
+    char* env = secure_getenv(env_var.c_str());
+#else
+    char* env = getenv(env_var.c_str());
+#endif
+    if (env == NULL) {
+        return false;
+    }
+    return true;
+}
+
 std::string get_env(
         const std::string& env_var
         )
 {
 #ifdef SPECMICP_HAVE_SECURE_GETENV
     char* env = secure_getenv(env_var.c_str());
 #else
     char* env = getenv(env_var.c_str());
 #endif
     if (env == NULL) {
         return "";
     }
     else return env;
 }
 } // end namespace utils
 } // end namespace specmicp
diff --git a/src/specmicp_common/filesystem.hpp b/src/specmicp_common/filesystem.hpp
index 4172765..8695b3f 100644
--- a/src/specmicp_common/filesystem.hpp
+++ b/src/specmicp_common/filesystem.hpp
@@ -1,82 +1,87 @@
 /* =============================================================================
 
  Copyright (c) 2014 - 2016
  F. Georget <fabieng@princeton.edu> Princeton University
  All rights reserved.
 
 
 Redistribution and use in source and binary forms, with or without modification,
 are permitted provided that the following conditions are met:
 
     1. Redistributions of source code must retain the above copyright notice,
     this list of conditions and the following disclaimer.
 
     2. Redistributions in binary form must reproduce the above copyright notice,
     this list of conditions and the following disclaimer in the documentation
     and/or other materials provided with the distribution.
 
     3. Neither the name of the copyright holder nor the names of its
     contributors may be used to endorse or promote products derived from this
     software without specific prior written permission.
 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. *
 
 ============================================================================= */
 
 #ifndef SPECMICP_UTILS_FILESYSTEM
 #define SPECMICP_UTILS_FILESYSTEM
 
 #include "macros.hpp"
 #include <string>
 #include <vector>
 
 namespace specmicp {
 namespace utils {
 
 //! \brief Check that the directory exist
 bool SPECMICP_DLL_PUBLIC is_directory(const std::string& path);
 
 //! \brief Check that the directory exist
 bool SPECMICP_DLL_PUBLIC is_file(const std::string& path);
 
 //! \brief Return the current directory
 std::string SPECMICP_DLL_PUBLIC get_current_directory();
 
 //! \brief Complete a path
 std::string SPECMICP_DLL_PUBLIC complete_path(
         const std::string& dir,
         const std::string& file
         );
 
 //! \brief Return an absolute path from a relative one
 //!
 //! If an error is detected then the return string will be empty,
 //! and error will contain a message about the error
 std::string SPECMICP_DLL_PUBLIC relative_to_absolute(
         const std::string& rel_path,
         std::string& error
         );
 
 //! \brief Return the complete path to a file from a set of directories
 std::string SPECMICP_DLL_PUBLIC find_path(
         std::string filename,
         const std::vector<std::string>& directories
         );
 
+//! \brief Return true if the environment variable is defined
+bool SPECMICP_DLL_PUBLIC has_env(
+        const std::string& env_var
+        );
+
 //! \brief Return an environment variable
 std::string SPECMICP_DLL_PUBLIC get_env(
         const std::string& env_var
         );
 } // end namespace utils
 } // end namespace specmicp
 
 #endif // SPECMICP_UTILS_FILESYSTEM
diff --git a/tests/specmicp_common/misc.cpp b/tests/specmicp_common/misc.cpp
index 1bf74b2..cd33ddd 100644
--- a/tests/specmicp_common/misc.cpp
+++ b/tests/specmicp_common/misc.cpp
@@ -1,615 +1,619 @@
 #include "catch.hpp"
 
 #include "specmicp_common/log.hpp"
 #include "specmicp_common/timer.hpp"
 #include "specmicp_common/physics/maths.hpp"
 #include "specmicp_common/moving_average.hpp"
 #include "specmicp_common/perfs_handler.hpp"
 #include "specmicp_common/options_handler.hpp"
 #include "specmicp_common/scope_guard.hpp"
 #include "specmicp_common/pimpl_ptr.hpp"
 #include "specmicp_common/cached_vector.hpp"
 #include "specmicp_common/string_algorithms.hpp"
 #include "specmicp_common/filesystem.hpp"
 
 #include <sstream>
 
 using namespace specmicp;
 
 //         TOC
 // =======================
 //
 //  1 - Logger
 //  2 - Timer
 //  3 - Average
 //  4 - Moving Average
 //  5 - Performance handler
 //  6 - Options handler
 //  7 - Scope guard
 //  8 - Pimpl pointer
 //  9 - Cached Vector
 // 10 - Named Cached Vector
 // 11 - String algorithms
 // 12 - Filesystem
 
 //         Logger
 // =======================
 
 TEST_CASE("Logger", "[io],[log]") {
     SECTION("Non init logging") {
         init_logger(nullptr, logger::LogLevel::Warning);
 
         // compilation test, and runtime test of not failling nullptr
 
         SPAM << "Spam";
         DEBUG << "Debug";
         INFO << "Info";
         WARNING << "Warning";
         ERROR << "Error";
         CRITICAL << "Critical";
     }
 
     SECTION("Level test") {
 
         std::stringstream stream_log;
         init_logger(&stream_log, logger::LogLevel::Warning);
 
         SPAM << "Spam";
         REQUIRE(stream_log.str().size() == 0);
         DEBUG << "Debug";
         REQUIRE(stream_log.str().size() == 0);
         INFO << "Info";
         REQUIRE(stream_log.str().size() == 0);
         WARNING << "Warning";
         REQUIRE(stream_log.str().size() != 0);
         stream_log.str("");
         ERROR << "Error";
         REQUIRE(stream_log.str().size() != 0);
         stream_log.str("");
         CRITICAL << "Critical";
         REQUIRE(stream_log.str().size() != 0);
         stream_log.str("");
 
 
         init_logger(&stream_log, logger::LogLevel::Debug);
         SPAM << "Spam";
         REQUIRE(stream_log.str().size() == 0);
         DEBUG << "Debug";
 #ifdef NDEBUG
         REQUIRE(stream_log.str().size() == 0);
 #else
         REQUIRE(stream_log.str().size() != 0);
 #endif
         stream_log.str("");
         INFO << "Info";
 #ifdef NDEBUG
         REQUIRE(stream_log.str().size() == 0);
 #else
         REQUIRE(stream_log.str().size() != 0);
      #endif
         stream_log.str("");
         WARNING << "Warning";
         REQUIRE(stream_log.str().size() != 0);
         stream_log.str("");
         ERROR << "Error";
         REQUIRE(stream_log.str().size() != 0);
         stream_log.str("");
         CRITICAL << "Critical";
         REQUIRE(stream_log.str().size() != 0);
         stream_log.str("");
     }
 }
 
 //          Timer
 // =======================
 
 TEST_CASE("Timer", "[time],[CPU]") {
 
     SECTION("Timer test") {
         Timer timer;
 
         timer.stop();
 
         CHECK(timer.elapsed_time() >= 0.0);
 
         timer.start();
         timer.stop();
 
         CHECK(timer.elapsed_time() >= 0.0);
 
         CHECK(timer.get_stop() >= timer.get_start());
 
         CHECK(timer.get_ctime_start() != nullptr);
         CHECK(timer.get_ctime_stop() != nullptr);
     }
 }
 
 //       Average
 // ====================
 
 #define test_average(method, a, b, sol) \
     CHECK(average<method>(a, b) == Approx(sol).epsilon(1e-10));
 
 #define test_average_vector(method, vector, sol) \
     CHECK(average<method>(vector) == Approx(sol).epsilon(1e-10));
 
 
 TEST_CASE("Average", "[average],[maths]") {
 
     Vector test_vector(4);
     test_vector << 1.0, 2.0, 3.0, 4.0;
 
     SECTION("Arithmetic average") {
 
         test_average(Average::arithmetic, 1.0, 1.0, 1.0);
         test_average(Average::arithmetic, 2.0, 1.0, 1.5);
         test_average(Average::arithmetic, -1.0, 1.0, 0.0);
 
         test_average_vector(Average::arithmetic, test_vector, 10.0/4);
     }
 
     SECTION("Harmonic average") {
 
         test_average(Average::harmonic, 1.0, 1.0, 1.0);
         test_average(Average::harmonic, 2.0, 1.0, 2.0/(1+0.5));
 
         test_average_vector(Average::harmonic, test_vector, 1.92);
     }
 
     SECTION("Geometric average") {
 
         test_average(Average::geometric, 1.0, 1.0, 1.0);
         test_average(Average::geometric, 1.0, 2.0, std::sqrt(2.0));
 
         test_average_vector(Average::geometric, test_vector, std::pow(24.0, 1.0/4.0));
 
     }
 }
 
 #undef test_average
 #undef test_average_vector
 
 //     Moving Average
 // =======================
 
 TEST_CASE("Moving average", "[average],[timestep]") {
     SECTION("Moving average test") {
 
         utils::ExponentialMovingAverage moving_average(0.1, 1.0);
 
         REQUIRE(moving_average.current_value() == 1.0);
 
         CHECK(moving_average.add_point(1.0) == 1.0);
 
         CHECK(moving_average.add_point(2.0) == 1.1);
         REQUIRE(moving_average.add_point(3.0) == 0.9*1.1+0.3);
 
         moving_average.reset(1.0);
         REQUIRE(moving_average.current_value() == 1.0);
 
         moving_average.set_alpha(0.2);
         REQUIRE(moving_average.add_point(2.0) == Approx(0.8+0.4));
 
 
     }
 }
 
 //  Performance handler
 // =======================
 
 struct MockPerf
 {
     scalar_t residuals {-1};
     index_t nb_iterations {-1};
 };
 
 class MockSolverPerf:
         public PerformanceHandler<MockPerf>
 {
 public:
     MockSolverPerf() {}
 
     void do_stuff() {
         get_perfs().residuals = 1e-6;
         get_perfs().nb_iterations = 10;
     }
 
     void reset_solver() {
         reset_perfs();
     }
 };
 
 TEST_CASE("PerformanceHandler", "[performance],[base]") {
     SECTION("Performance handler test") {
         auto my_solver = MockSolverPerf();
 
         const auto& perfs = my_solver.get_perfs();
         CHECK(perfs.nb_iterations == -1);
         CHECK(perfs.residuals == -1);
 
         my_solver.do_stuff();
         CHECK(perfs.nb_iterations == 10);
         CHECK(perfs.residuals == 1e-6);
 
         my_solver.reset_solver();
         CHECK(perfs.nb_iterations == -1);
         CHECK(perfs.residuals == -1);
 
     }
 }
 
 //  Options handler
 // =======================
 
 struct MockOptions
 {
     MockOptions()
     {}
 
     MockOptions(scalar_t res, index_t max_iter):
         residuals(res),
         max_iterations(max_iter)
     {}
 
     scalar_t residuals {1e-6};
     index_t max_iterations {100};
 };
 
 class MockSolverOptions:
         public OptionsHandler<MockOptions>
 {
 public:
     MockSolverOptions() {}
 
     MockSolverOptions(scalar_t res, index_t max_iter):
        OptionsHandler(res, max_iter)
     {}
 
 };
 
 TEST_CASE("Options handler", "[options],[base]") {
     SECTION("Options handler test") {
         auto my_solver_default = MockSolverOptions();
 
         const auto& ro_options = my_solver_default.get_options();
 
         CHECK(ro_options.max_iterations == 100);
         CHECK(ro_options.residuals == 1e-6);
 
         auto& rw_options = my_solver_default.get_options();
 
         rw_options.max_iterations = 10;
         rw_options.residuals = 1e-4;
 
         CHECK(ro_options.max_iterations == 10);
         CHECK(ro_options.residuals == 1e-4);
 
     }
 
     SECTION("Options handler - non default initialization") {
         auto my_solver = MockSolverOptions(1e-4, 10);
 
         const auto& ro_options = my_solver.get_options();
 
         CHECK(ro_options.max_iterations == 10);
         CHECK(ro_options.residuals == 1e-4);
 
 
     }
 }
 
 // ScopeGuard
 // ==========
 
 static void will_fail(bool& hop) {
     auto guard = utils::make_scope_guard([&hop]{hop=true;});
     throw std::runtime_error("fail on purpose");
     guard.release();
 }
 
 static void dont_fail(bool& hop) {
     auto guard = utils::make_scope_guard([&hop]{hop=true;});
     hop = false;
     guard.release();
 }
 
 TEST_CASE("Scope guard", "[utils]") {
     SECTION("Catch error") {
         bool hop = false;
         REQUIRE_THROWS_AS(will_fail(hop), std::runtime_error);
         CHECK(hop == true);
 
         dont_fail(hop);
         CHECK(hop == false);
     }
 }
 
 // pimpl_ptr
 // =========
 
 // simple Interface + Implementation to test pimpl_ptr
 class MockImplementation
 {
 public:
     MockImplementation(double a):
         m_a(a)
     {}
 
     double add(double b) const {return m_a + b;}
 
     // Compilation should failed if this one is activated
     //double add(double b) {return m_a + b;}
 
     void set(double new_a) { m_a = new_a;}
 
 private:
     double m_a;
 };
 
 class MockInterface
 {
 public:
     MockInterface(double a):
         m_impl(utils::make_pimpl<MockImplementation>(a))
     {}
 
     double add(double b) const {return m_impl->add(b);}
 
     void set(double new_a) {return m_impl->set(new_a);}
 
 private:
     utils::pimpl_ptr<MockImplementation> m_impl;
 };
 
 TEST_CASE("pimpl_ptr", "[utils],[pointer],[const]") {
     SECTION("Test mock") {
         auto hop = MockImplementation(1.0);
 
         CHECK(hop.add(2.0) == Approx(3.0));
         hop.set(2.0);
         CHECK(hop.add(2.0) == Approx(4.0));
     }
 
     //SECTION("compilation fail") {
     //    const MockInterface fail1(2.0);
     //    fail1.set(3.0);
     //}
 }
 
 // Cached Vector
 //
 
 TEST_CASE("Cached vector", "[utils],[container],[cache]")
 {
     SECTION("Default") {
         utils::CachedVector<std::string> cached;
         cached.push_back("value0");
         cached.push_back(0);
 
         CHECK(cached.size() == 2);
         CHECK(cached.size_cache() == 1);
         CHECK(cached[0] == "value0");
         CHECK(cached[1] == "value0");
 
         for (auto& it: cached) {
             CHECK(it == "value0");
         }
 
         cached.emplace_back("truc");
         CHECK(cached[2] == "truc");
         cached.emplace_back("other");
         CHECK(cached[3] == "other");
 
         cached.push_back(2);
         CHECK(cached.at(4) == "other");
 
         CHECK(cached.size() == 5);
         CHECK(cached.size_cache() == 3);
 
         auto& new_val = cached.fork(1);
         new_val = "plop";
         CHECK(cached[1] == "plop");
 
         for (auto it=cached.begin_index(); it!=cached.cend_index();++it)
         {
             CHECK(*it < cached.size());
             CHECK(*it >= 0);
         }
 
         //! it's possible, absolutely not a good idea
         for (auto& value: cached) {
             value = "reinit";
         }
 
         CHECK(cached[2] == "reinit");
     }
 
     SECTION("Default constructor") {
         static_assert(std::is_default_constructible<std::string>::value,
                       "String is default constructible"
                       );
         utils::CachedVector<std::string> cached(5);
         CHECK(cached[4] == "");
     }
 }
 
 // Named Cached Vector
 
 TEST_CASE("NamedCachedVector", "[utils],[container],[cache]")
 {
     SECTION("Default") {
         utils::NameCachedVector<std::string> cached(
                     5, "default_name", "default_value");
 
         CHECK(cached.size_cache() == 1);
         CHECK(cached.size() == 5);
         CHECK(cached.get("default_name") == "default_value");
 
         auto& forked = cached.fork(2, "new name");
         forked = "new value";
 
         CHECK(cached.size_cache() == 2);
         CHECK(cached.size() == 5);
         CHECK(cached[2] == "new value");
         CHECK(cached.get("new name") == "new value");
 
         CHECK(cached.has_value("new name"));
         CHECK(not cached.has_value("not a name"));
 
         cached.push_back_cache("another name", "another value");
         CHECK(cached.get("another name") == "another value");
         CHECK(cached.size_cache() == 3);
         CHECK(cached.size() == 5);
 
         for (auto& value: cached)
         {
             CHECK(value != "another value");
         }
 
     }
 
     SECTION("Default constructor") {
         static_assert(std::is_default_constructible<std::string>::value,
                       "String is default constructible"
                       );
         utils::NameCachedVector<std::string> cached(5, "default");
         CHECK(cached[4] == "");
     }
 }
 
 // String Algorithms
 // =================
 
 TEST_CASE("String algorithms", "[utils],[string],[algorithms]")
 {
     SECTION("split") {
 
         std::string test1 = "a";
         CHECK(utils::split(test1, ',') == std::vector<std::string>({"a", }));
 
         std::string test2 = "a,b,c";
         CHECK(utils::split(test2, ',') == std::vector<std::string>({"a", "b", "c"}));
 
         std::string test3 = "a,b,c,";
         CHECK(utils::split(test3, ',') == std::vector<std::string>({"a", "b", "c"}));
 
     }
 
     SECTION("strip") {
         CHECK(utils::strip("hop") == "hop");
         CHECK(utils::strip(" hop") == "hop");
         CHECK(utils::strip("hop ") == "hop");
         CHECK(utils::strip(" hop ") == "hop");
         CHECK(utils::strip(" hop hop ") == "hop hop");
         CHECK(utils::strip(" ") == "");
 
     }
 
     SECTION("range_indices") {
         CHECK(utils::range_indices("1") == std::vector<index_t>({1, }));
         CHECK(utils::range_indices("-1:3") == std::vector<index_t>({-1, 0, 1, 2, 3}));
         CHECK(utils::range_indices("1,5") == std::vector<index_t>({1, 5}));
         CHECK(utils::range_indices<index_t>("1,3:5") == std::vector<index_t>({1, 3, 4, 5}));
         CHECK(utils::range_indices("1,5,") == std::vector<index_t>({1, 5}));
         CHECK(utils::range_indices("1, 3:5, 2") == std::vector<index_t>({1, 2, 3, 4, 5,}));
 
 
         CHECK(utils::range_indices<uindex_t>("1,3:5") == std::vector<uindex_t>({1, 3, 4, 5}));
         CHECK_THROWS_AS(utils::range_indices<uindex_t>("1,-3:5"), std::invalid_argument);
         CHECK_THROWS_AS(utils::range_indices<uindex_t>("-2"), std::invalid_argument);
     }
 
     SECTION("parse expr") {
         CHECK(utils::parse_expression<scalar_t>("2.0") == 2.0);
         CHECK(utils::parse_expression<scalar_t>("-2.0") == -2.0);
         CHECK(utils::parse_expression<scalar_t>("2.0 +2.0") == 4.0);
         CHECK(utils::parse_expression<scalar_t>("2.0/ 2.0") == 1.0);
         CHECK(utils::parse_expression<scalar_t>("3 + 2.0 / 2.0") == 4.0);
         CHECK(utils::parse_expression<scalar_t>("1e-6") == 1e-6);
         CHECK(utils::parse_expression<scalar_t>("2*1e-6") == 2e-6);
         CHECK(utils::parse_expression<scalar_t>("1e-6-2") == 1e-6-2);
 
         CHECK(utils::parse_expression<scalar_t>("3 + a / 2.0", {{"a", 2}}) == 4.0);
         CHECK(utils::parse_expression<scalar_t>("a + b / c",
             {{"a", 2,}, {"b", 3.0}, {"c", 6.0}}) == 2.5);
 
         CHECK_THROWS(utils::parse_expression<scalar_t>("234.53as"));
         CHECK_THROWS(utils::parse_expression<scalar_t>("3 + a / 2.0", {{"b", 2}}));
         CHECK_THROWS(utils::parse_expression<scalar_t>("3 + a/ / 2.0", {{"a", 2}}));
         CHECK_THROWS(utils::parse_expression<scalar_t>("3 + a // 2.0", {{"a", 2}}));
 
     }
 
     SECTION("string to bool") {
         CHECK(utils::string_to_bool("True")  == true);
         CHECK(utils::string_to_bool(" true") == true);
         CHECK(utils::string_to_bool("1")     == true);
         CHECK(utils::string_to_bool("yes ")  == true);
         CHECK(utils::string_to_bool("Yes")   == true);
         CHECK(utils::string_to_bool(" Y ")   == true);
 
 
         CHECK(utils::string_to_bool("False")  == false);
         CHECK(utils::string_to_bool("false ") == false);
         CHECK(utils::string_to_bool(" 0 ")    == false);
         CHECK(utils::string_to_bool(" no  ")  == false);
         CHECK(utils::string_to_bool(" No")    == false);
         CHECK(utils::string_to_bool("N ")     == false);
 
         CHECK_THROWS_AS(utils::string_to_bool("plop"), std::invalid_argument);
         CHECK_THROWS_AS(utils::string_to_bool("  plop"), std::invalid_argument);
         CHECK_THROWS_AS(utils::string_to_bool("Faolse"), std::invalid_argument);
     }
 }
 
 // Filesystem
 // ===========
 
 TEST_CASE("filesystem", "[io],[dir],[filesystem]") {
     SECTION("is directory") {
         CHECK(utils::is_directory(CURRENT_DIRECTORY));
         CHECK_FALSE(utils::is_directory("test_common"));
         CHECK_FALSE(utils::is_directory("mouahahahah"));
     }
     SECTION("is directory") {
         CHECK_FALSE(utils::is_file(CURRENT_DIRECTORY));
         CHECK(utils::is_file("test_common"));
         CHECK(utils::is_file(utils::complete_path(
                                  CURRENT_DIRECTORY, "test_common")));
     }
 
     SECTION("Current directory") {
         CHECK(utils::get_current_directory() == CURRENT_DIRECTORY);
     }
 
     SECTION("Complete path") {
         CHECK(utils::complete_path("/usr/include/", "dirent.h") ==
               "/usr/include/dirent.h");
         CHECK(utils::complete_path("/usr/include", "dirent.h") ==
               "/usr/include/dirent.h");
     }
 
     SECTION("Absolute path") {
         std::string error = "";
         CHECK(utils::relative_to_absolute("./test_common", error) ==
               utils::complete_path(CURRENT_DIRECTORY, "test_common"));
         CHECK(error == "");
 
         CHECK(utils::relative_to_absolute("../../platypus.duck", error) == "");
         CHECK(error != "");
 
     }
 
     SECTION("Find path") {
         CHECK(utils::find_path("dirent.h", {"/usr/include"})
               == "/usr/include/dirent.h");
 
         CHECK(utils::find_path("not_found_becuase_.h", {"/usr/include"})
               == "");
     }
 
+    SECTION("has_env") {
+        CHECK(utils::has_env("USER"));
+        CHECK_FALSE(utils::has_env("platypus_platypus_platypys_35897037289589"));
+    }
     SECTION("get_env") {
         CHECK(utils::get_env("USER") != "");
         CHECK(utils::get_env("platypus_platypus_platypys_35897037289589") == "");
     }
 }