diff --git a/.drone.yml b/.drone.yml
index 867a640..6f08113 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -26,10 +26,12 @@ steps:
   - alias apt-get='rm -f /var/cache/apt/archives/lock && apt-get'
   - apt-get update -q
   - apt-get install -qq build-essential cmake
+  - apt-get install -qq catch
   - rm -rf build && mkdir -p build && cd build
-  - cmake -G "Unix Makefiles" ..
+  - cmake -G "Unix Makefiles" -DWITH_TESTS=YES ..
   - make VERBOSE=1
   - make install DESTDIR=install
+  - cd tests && ctest -V
   volumes:
   - name: debian-package-cache
     path: /var/cache/apt/archives
@@ -47,10 +49,12 @@ steps:
   - alias apt-get='rm -f /var/cache/apt/archives/lock && apt-get'
   - apt-get update -q
   - apt-get install -qq build-essential cmake
+  - apt-get install -qq catch
   - rm -rf build && mkdir -p build && cd build
-  - cmake -G "Unix Makefiles" ..
+  - cmake -G "Unix Makefiles" -DWITH_TESTS=YES ..
   - make VERBOSE=1
   - make install DESTDIR=install
+  - cd tests && ctest -V
   volumes:
   - name: debian-package-cache
     path: /var/cache/apt/archives
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7d56a9d..5bc30ed 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -18,7 +18,7 @@ project(mastodonpp
 list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake")
 
 # Project build options.
-# option(WITH_TESTS "Compile tests." NO)
+option(WITH_TESTS "Compile tests." NO)
 # option(WITH_DOC "Generate HTML documentation." YES)
 # option(WITH_EXAMPLES "Compile examples." NO)
 # option(WITH_DEB "Prepare for the building of .deb packages." NO)
@@ -32,8 +32,8 @@ include(debug_flags)
 
 add_subdirectory(src)
 
-# if(WITH_TESTS)
-#   add_subdirectory(tests)
-# endif()
+if(WITH_TESTS)
+  add_subdirectory(tests)
+endif()
 
 # include(cmake/packages.cmake)
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
new file mode 100644
index 0000000..3f7107b
--- /dev/null
+++ b/tests/CMakeLists.txt
@@ -0,0 +1,27 @@
+include(CTest)
+
+file(GLOB sources_tests test_*.cpp)
+
+find_package(Catch2 CONFIG)
+if(Catch2_FOUND)                # Catch 2.x
+  include(Catch)
+  add_executable(all_tests main.cpp ${sources_tests})
+  target_link_libraries(all_tests
+    PRIVATE Catch2::Catch2 ${PROJECT_NAME})
+  target_include_directories(all_tests PRIVATE "/usr/include/catch2")
+  catch_discover_tests(all_tests EXTRA_ARGS "${EXTRA_TEST_ARGS}")
+else()                          # Catch 1.x
+  if(EXISTS "/usr/include/catch.hpp")
+    message(STATUS "Catch 1.x found.")
+    foreach(src ${sources_tests})
+      get_filename_component(bin ${src} NAME_WE)
+      add_executable(${bin} main.cpp ${src})
+      target_link_libraries(${bin}
+        PRIVATE ${PROJECT_NAME})
+      add_test(${bin} ${bin} "${EXTRA_TEST_ARGS}")
+    endforeach()
+  else()
+    message(FATAL_ERROR
+      "Neither Catch 2.x nor Catch 1.x could be found.")
+  endif()
+endif()
diff --git a/tests/main.cpp b/tests/main.cpp
new file mode 100644
index 0000000..162dfdf
--- /dev/null
+++ b/tests/main.cpp
@@ -0,0 +1,19 @@
+/*  This file is part of mastodonpp.
+ *  Copyright © 2020 tastytea <tastytea@tastytea.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define CATCH_CONFIG_MAIN
+
+#include <catch.hpp>
diff --git a/tests/test_instanciation.cpp b/tests/test_instanciation.cpp
new file mode 100644
index 0000000..3fbc0f3
--- /dev/null
+++ b/tests/test_instanciation.cpp
@@ -0,0 +1,51 @@
+/*  This file is part of mastodonpp.
+ *  Copyright © 2020 tastytea <tastytea@tastytea.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "mastodonpp.hpp"
+
+#include <catch.hpp>
+
+#include <exception>
+#include <string>
+
+namespace mastodonpp
+{
+
+using std::string;
+
+SCENARIO ("API can be instantiated.")
+{
+    bool exception = false;
+
+    GIVEN ("One instanciation.")
+    {
+        try
+        {
+            API masto("example.com", "");
+        }
+        catch (const std::exception &e)
+        {
+            exception = true;
+        }
+
+        THEN ("No exception is thrown")
+        {
+            REQUIRE_FALSE(exception);
+        }
+    }
+}
+
+} // namespace mastodonpp